NAVLE (North American Veterinary Licensing Exam) — Questions and Answers

Question 1: A 6-year-old Standardbred pacer develops progressive bilateral hindlimb ataxia and weakness that worsens going downhill. Cervical radiographs show vertebral canal stenosis at C4-C5. What is the most likely diagnosis?

Stringhalt
Equine herpesvirus myeloencephalopathy
Cervical vertebral stenotic myelopathy (Wobbler syndrome) (Correct answer)
Equine protozoal myeloencephalitis (EPM)

Correct answer: Cervical vertebral stenotic myelopathy (Wobbler syndrome)

Cervical vertebral stenotic myelopathy (Wobbler syndrome) presents with progressive spinal cord compression causing symmetric ataxia and weakness, confirmed by vertebral canal stenosis on radiographs.

Question 2: A veterinarian suspects a case of highly pathogenic avian influenza (HPAI) in a commercial flock. The first regulatory notification must be made to:

CDC influenza division
FDA Center for Veterinary Medicine
State veterinarian or USDA APHIS (Correct answer)
Local law enforcement

Correct answer: State veterinarian or USDA APHIS

HPAI is a federally reportable disease; the state veterinarian and USDA APHIS must be notified immediately upon suspicion.

Question 3: A 7-year-old intact female ferret (Mustela putorius furo) presents with bilateral symmetric alopecia starting at the tail base, a 20% body weight loss over 2 months, a palpable cranial abdominal mass, and a blood glucose of 38 mg/dL. Which combination of conditions MOST likely explains this presentation, and what is the underlying endocrine interrelationship?

Primary hypothyroidism causing alopecia and cold intolerance with secondary insulinoma from reduced hepatic glucose output
Ovarian remnant syndrome causing estrogen-mediated alopecia and concurrent hepatic lipidosis with hypoglycemia
Hyperadrenocorticism causing insulin resistance and secondary reactive hypoglycemia with concurrent lymphoma
Adrenal neoplasia causing androgen excess and concurrent insulinoma; adrenal androgens may promote pancreatic beta-cell hyperplasia (Correct answer)

Correct answer: Adrenal neoplasia causing androgen excess and concurrent insulinoma; adrenal androgens may promote pancreatic beta-cell hyperplasia

This ferret has classic 'ferret adrenal disease' (hyperandrogenism from adrenocortical neoplasia or hyperplasia) presenting with tail-base alopecia and concurrent insulinoma (pancreatic beta-cell tumor). In North American domestic ferrets, adrenal disease and insulinoma co-occur at rates significantly above chance — estimated at 30–50% concurrent presentation. Research suggests adrenal androgens, particularly androstenedione, may have a trophic effect on pancreatic islet cells, promoting beta-cell hyperplasia and neoplasia. The hypoglycemia (38 mg/dL) with the abdominal mass and weight loss confirms insulinoma alongside the adrenal signs.

Question 4: A 7-year-old intact male cat develops acute urethral obstruction. After relief of the obstruction, the cat develops profound bradycardia (HR 48 bpm), peaked T waves on ECG, and a serum potassium of 8.9 mEq/L. Which treatment should be administered FIRST?

Regular insulin + dextrose IV to drive potassium into cells
Calcium gluconate IV to stabilize cardiac membrane potential (Correct answer)
Furosemide IV to promote renal potassium excretion
Sodium bicarbonate IV to shift potassium intracellularly

Correct answer: Calcium gluconate IV to stabilize cardiac membrane potential

In life-threatening hyperkalemia with cardiac arrhythmias, calcium gluconate is the immediate priority. It does not lower serum potassium but rapidly stabilizes cardiomyocyte membrane potential, buying time to address the underlying cause. Insulin/dextrose and sodium bicarbonate do shift potassium intracellularly but take longer to act and do not protect the heart as immediately. Furosemide requires adequate renal function and acts too slowly in an acute crisis.

Question 5: Which antibiotic classes are contraindicated in rabbits due to the risk of fatal clostridial enterotoxemia?

Chloramphenicol
Trimethoprim-sulfonamide combinations
Fluoroquinolones (e.g., enrofloxacin)
Penicillins and lincosamides (e.g., clindamycin, ampicillin) (Correct answer)

Correct answer: Penicillins and lincosamides (e.g., clindamycin, ampicillin)

Penicillins, amoxicillin, and lincosamides disrupt cecal flora and allow Clostridium species overgrowth, causing fatal enterotoxemia in rabbits.

Question 6: Which vaccination protocol is most appropriate for preventing clostridial diseases (blackleg, malignant edema) in beef calves?

Passive transfer via colostrum is sufficient without active vaccination
Single dose at weaning only
Monthly intranasal vaccine starting at birth
Two doses 3-4 weeks apart starting at 2-3 months of age with annual boosters (Correct answer)

Correct answer: Two doses 3-4 weeks apart starting at 2-3 months of age with annual boosters

Clostridial vaccines require a primary series of two doses 3-4 weeks apart to achieve protective immunity, with annual boosters to maintain protection.

Question 7: Which biosecurity measure is most effective at preventing introduction of Johne's disease (paratuberculosis) into a closed beef herd?

Quarantining new arrivals for 14 days in a separate pen
Vaccinating all incoming animals with killed M. paratuberculosis vaccine
Purchasing animals from Johne's-tested herds and testing all additions (Correct answer)
Testing fecal samples from all animals annually with PCR

Correct answer: Purchasing animals from Johne's-tested herds and testing all additions

Because no test has 100% sensitivity for Johne's disease, purchasing from certified low-prevalence herds combined with pre-purchase testing provides the best risk reduction.

Question 8: A 9-year-old spayed female Cocker Spaniel presents with progressive exercise intolerance, a 3/6 left apical systolic murmur, and radiographic evidence of left atrial enlargement without pulmonary edema. Echocardiography confirms myxomatous mitral valve disease (MMVD) with a left atrial-to-aortic root ratio (LA:Ao) of 1.7. Which management decision is most consistent with current ACVIM consensus guidelines for this patient?

Recheck echocardiography in 6 months; initiate pimobendan only if LA:Ao ≥ 1.7 persists at that recheck
Begin enalapril immediately to reduce cardiac remodeling
Begin pimobendan immediately to delay onset of congestive heart failure (Correct answer)
Begin furosemide prophylactically to prevent fluid accumulation

Correct answer: Begin pimobendan immediately to delay onset of congestive heart failure

Per the 2019 ACVIM consensus guidelines for MMVD (EPIC trial criteria), dogs in Stage B2 — defined as radiographic cardiomegaly OR LA:Ao ≥ 1.7 on echo — should be started on pimobendan to delay onset of CHF. An LA:Ao of 1.7 meets the echocardiographic threshold for Stage B2, making pimobendan initiation appropriate now. Enalapril was not shown to significantly delay CHF onset in Stage B dogs in the SVEP trial. Furosemide is reserved for Stage C (active CHF) and should not be used prophylactically.

Question 9: On orthogonal radiographs of a long bone, periosteal new bone with a 'sunburst' pattern is MOST characteristic of:

Primary bone tumor (osteosarcoma) (Correct answer)
Nutritional secondary hyperparathyroidism
Septic osteomyelitis
Hypertrophic osteopathy

Correct answer: Primary bone tumor (osteosarcoma)

A sunburst or spiculated periosteal reaction radiating perpendicular to the cortex is a classic aggressive pattern associated with osteosarcoma.

Question 10: What is the most reliable and practical method for assessing failure of passive transfer (FPT) in a 2-day-old calf on-farm?

Serum total protein measurement via refractometer (Correct answer)
Visual assessment of calf vigor and suckle reflex
Zinc sulfate turbidity test
Radial immunodiffusion (RID) assay

Correct answer: Serum total protein measurement via refractometer

Measuring serum total protein (STP) with a refractometer is a widely used, practical, and reliable on-farm method to estimate passive immunity status. In neonatal calves, immunoglobulins (primarily IgG) make up a large portion of serum proteins, so there is a strong correlation between STP and serum IgG levels. While RID is the gold standard for directly measuring IgG, it is a laboratory test and not practical for immediate, on-farm assessment. Visual assessment is unreliable, and the zinc sulfate turbidity test is an older, less accurate method.

Question 11: Which of the following describes the classic gait abnormality associated with Australian stringhalt?

Ataxia and paresis, most pronounced in the hindlimbs, that worsens with circling.
A dragging of the toes of the hind feet, resulting in squared-off hoof wear.
A short, choppy stride in the forelimbs, often described as 'walking on eggshells'.
A spastic, involuntary hyperflexion of one or both hindlimbs during movement. (Correct answer)

Correct answer: A spastic, involuntary hyperflexion of one or both hindlimbs during movement.

Stringhalt is a neuromuscular condition characterized by an involuntary, spasmodic, and exaggerated upward flexion of one or both hindlimbs during the protraction phase of the stride. Australian stringhalt is a specific form, often seen in outbreaks, associated with the ingestion of toxic plants like Hypochaeris radicata (flatweed). The gait is often described as a jerking or snapping of the hindlimb up toward the abdomen.

Question 12: Which of the following correctly describes 'first-pass metabolism'?

Drug elimination by the kidneys after IV administration
The initial drug distribution phase immediately after IV injection
Metabolism occurring in the GI lumen before absorption
Hepatic metabolism that reduces bioavailability of orally administered drugs before reaching systemic circulation (Correct answer)

Correct answer: Hepatic metabolism that reduces bioavailability of orally administered drugs before reaching systemic circulation

First-pass metabolism refers to the hepatic biotransformation of an orally administered drug as it passes through the portal circulation before reaching systemic circulation, reducing bioavailability.

Question 13: A closed beef herd of 300 Angus cows has had three consecutive years of late-gestation abortions (>7 months), averaging 4.5% abortion rate. Aborted fetuses show autolysis. Paired serology on 15 aborting cows shows no significant titer rise to IBR, BVD, leptospirosis (5-serovar panel), or Neospora caninum. Fetal abomasal content culture is negative. The pastures border a large white-tailed deer population. Which diagnostic step has the HIGHEST probability of identifying the etiology?

Perform Brucella abortus serology on all cows using card test and ELISA, with culture of placenta on Farrell's medium
Test the herd for bovine viral diarrhea virus (BVDV) persistent infection by antigen ELISA ear notch on all animals
Submit fresh and formalin-fixed fetal tissues for PCR and histopathology targeting Epizootic Hemorrhagic Disease virus (EHD) and Bluetongue virus (Correct answer)
Submit soil and water samples from border pastures for Nitrate/nitrite quantification and mycotoxin panel

Correct answer: Submit fresh and formalin-fixed fetal tissues for PCR and histopathology targeting Epizootic Hemorrhagic Disease virus (EHD) and Bluetongue virus

The epidemiologic profile — late-gestation abortions, proximity to white-tailed deer (the primary amplifying host), and negative results for common abortifacients — strongly implicates an Orbivirus. EHD virus (serotypes 1, 2, 6, 7) and Bluetongue virus are transmitted by Culicoides midges, are amplified in deer populations, and can cause late-term abortion, fetal edema, and hemorrhage in cattle — often with autolytic fetuses making serology the only ante-mortem option in the dam. Importantly, EHD is frequently under-diagnosed because standard bovine abortion panels do not routinely include it. PCR on fresh fetal spleen, lung, and brain, combined with histopathology showing fetal vasculitis, would be confirmatory. Brucellosis is a legitimate consideration but would be unusual in a closed, vaccinated herd with no travel history and is mandatorily reportable, making it higher-profile. BVDV-PI cattle cause early losses, not clustering in late gestation.

Question 14: A 3-year-old intact male domestic shorthair presents with progressive neurological signs including ataxia, vertical nystagmus, and behavioral changes over 6 weeks. CSF analysis reveals a protein of 420 mg/dL with a mixed pleocytosis (predominantly neutrophils and macrophages). Coronavirus antibody titer in CSF is 1:3200. Abdominal ultrasound shows no effusion. Which histopathological finding in the brain would be MOST pathognomonic for the underlying diagnosis?

Multifocal necrotizing encephalitis with calvarial bone lysis
Perivascular pyogranulomatous inflammation with fibrinous vasculitis affecting small and medium vessels (Correct answer)
Eosinophilic intranuclear inclusions within astrocytes and oligodendrocytes
Diffuse lymphoplasmacytic meningoencephalitis with Virchow-Robin space infiltration

Correct answer: Perivascular pyogranulomatous inflammation with fibrinous vasculitis affecting small and medium vessels

Feline Infectious Peritonitis (FIP) caused by virulent feline coronavirus (FCoV) mutation produces a characteristic perivascular pyogranulomatous inflammation with fibrinous vasculitis. This reflects immune-complex deposition and Type III hypersensitivity driving vasculitis of CNS vessels. The non-effusive (dry) form disproportionately affects the CNS and eyes. The mixed neutrophilic-macrophage CSF pleocytosis with markedly elevated protein and high FCoV antibody titer in CSF strongly support neurotropic FIP, but the perivascular pyogranulomatous vasculitis is the pathognomonic histopathological hallmark.

Question 15: A 10-year-old DSH cat presents with polyuria, polydipsia, and a palpable ventral neck mass. Serum T4 is 8.2 µg/dL (normal 0.8–4.0). Which cardiac abnormality is most commonly associated with this condition?

Restrictive cardiomyopathy
Hypertrophic cardiomyopathy (Correct answer)
Pericardial effusion
Dilated cardiomyopathy

Correct answer: Hypertrophic cardiomyopathy

Hyperthyroidism in cats most commonly causes hypertrophic cardiomyopathy due to the chronotropic and inotropic effects of excess thyroid hormone.

Question 16: A beef producer wants to improve weaning weights and post-weaning growth. Which management practice during the preconditioning period (45-60 days post-weaning) has the GREATEST impact on feedlot health outcomes?

Administering growth implants immediately at weaning
Providing ad libitum grain access from birth
Completing vaccination series, weaning, castration, and dehorning at least 45 days before sale (Correct answer)
Keeping calves on the cow for 9 months before weaning

Correct answer: Completing vaccination series, weaning, castration, and dehorning at least 45 days before sale

Preconditioning programs that complete the BRD vaccination series, castration, and dehorning at least 45 days before sale reduce feedlot morbidity and mortality by allowing stress recovery and vaccine immune response maturation.

Question 17: What is the gold standard diagnostic test for confirming wet (effusive) FIP?

Effusion fluid RT-PCR for FCoV with immunostaining of macrophages (Correct answer)
Serum coronavirus antibody titer >1:3200
Abdominal ultrasound showing mesenteric lymphadenopathy
Complete blood count showing lymphopenia

Correct answer: Effusion fluid RT-PCR for FCoV with immunostaining of macrophages

Immunostaining for FCoV antigen within macrophages in effusion fluid or tissue biopsy is the gold standard for definitive FIP diagnosis.

Question 18: A 9-year-old Miniature Schnauzer presents with acute pancreatitis confirmed on abdominal ultrasound and elevated spec cPL. Three days into hospitalization with IV fluids and analgesia, the dog develops icterus. Bilirubin is 8.2 mg/dL (predominantly direct). ALP is 1,200 U/L and GGT is 180 U/L. The dog remains anorexic. Abdominal ultrasound now shows a dilated common bile duct at 6 mm. What is the most likely underlying cause of the new icterus?

Drug-induced cholestasis from opioid administration
Hepatic lipidosis developing from prolonged anorexia
Concurrent immune-mediated hemolytic anemia triggered by pancreatitis
Extrahepatic biliary obstruction (EHBO) secondary to pancreatic inflammation (Correct answer)

Correct answer: Extrahepatic biliary obstruction (EHBO) secondary to pancreatic inflammation

The combination of acute pancreatitis, predominantly direct (conjugated) hyperbilirubinemia, markedly elevated ALP and GGT (cholestatic pattern), and a dilated common bile duct (>5 mm in dogs is abnormal) is classic for extrahepatic biliary obstruction (EHBO). Pancreatic inflammation causes edema and compression of the common bile duct as it traverses the mesoduodenum adjacent to the pancreas. IMHA would cause predominantly indirect (unconjugated) hyperbilirubinemia with spherocytes and a positive Coombs test. Hepatic lipidosis is more characteristic of cats. Opioid-induced sphincter of Oddi spasm can cause mild biliary dilation but typically does not cause this degree of bilirubinemia.

Question 19: Which fluoroquinolone antibiotic is most associated with acute retinal degeneration and blindness in cats when used at high doses?

Orbifloxacin
Pradofloxacin
Enrofloxacin (Correct answer)
Marbofloxacin

Correct answer: Enrofloxacin

Enrofloxacin at doses above 5 mg/kg/day causes retinal degeneration in cats due to accumulation in the retinal pigment epithelium.

Question 20: A dog has a myelogram that shows a contrast column that is deviated to one side and compressed at a single level but does not completely stop. This pattern is most consistent with:

Intradural-extramedullary mass
Intramedullary lesion (tumor/edema)
Normal variant
Extradural compression (disc herniation) (Correct answer)

Correct answer: Extradural compression (disc herniation)

Extradural lesions (such as disc material or vertebral bone) deviate and compress the contrast column from the outside without interrupting the intrathecal flow completely.

Question 21: On thoracic radiographs, a cat with hypertrophic cardiomyopathy (HCM) most commonly shows which cardiac silhouette shape on the VD view?

Valentine heart shape (biatrial enlargement) (Correct answer)
Globoid (round) silhouette
Normal silhouette despite severe disease
Right-sided enlargement with D-shape

Correct answer: Valentine heart shape (biatrial enlargement)

HCM in cats classically produces a 'valentine heart' shape on VD radiographs due to bilateral atrial enlargement, though some cats have relatively normal-appearing hearts.

Question 22: A 5-year-old outdoor cat presents with a chronic non-healing ulcer on the nasal planum, conjunctivitis with corneal ulceration, and recurrent mucopurulent nasal discharge. Herpesvirus (FHV-1) is confirmed by PCR from conjunctival swab. The owner asks about long-term management. Which antiviral strategy has the STRONGEST evidence base for reducing FHV-1-associated ocular disease severity in cats, with the LEAST systemic toxicity concern?

Topical 3% vidarabine ointment applied 5 times daily combined with oral lysine supplementation at 500 mg/day
Systemic acyclovir at 50 mg/kg PO q8h due to its established safety in cats
Oral famciclovir 90 mg/kg PO q8h as the first-line systemic antiviral
Topical 0.5% cidofovir ophthalmic solution applied twice daily to the affected eye(s) (Correct answer)

Correct answer: Topical 0.5% cidofovir ophthalmic solution applied twice daily to the affected eye(s)

Topical 0.5% cidofovir (a nucleotide analog) applied twice daily has been shown in clinical studies to significantly reduce FHV-1 conjunctival disease severity and viral shedding with minimal systemic absorption and low local toxicity — making it superior in the topical antiviral category for feline herpesvirus ocular disease. Famciclovir is the preferred oral antiviral (prodrug converted to penciclovir in cats), but the dose is 90 mg/kg PO q12h (NOT q8h) and it is reserved for severe systemic disease. Acyclovir is CONTRAINDICATED in cats due to severe nephrotoxicity and bone marrow suppression. Lysine supplementation has been shown in multiple systematic reviews to have NO benefit for FHV-1 management and is no longer recommended by the American Association of Feline Practitioners (AAFP).

Question 23: Which of the following is the most accurate description of a 'chip fracture' at the dorsal aspect of the proximal interphalangeal joint in a performance horse?

A subchondral cystic lesion within the proximal interphalangeal joint
An osteochondral fragment typically arising from the dorsal proximal rim of the middle phalanx (Correct answer)
A traumatic fracture of the extensor process of the distal phalanx
A stress fracture of the palmar cortex of the middle phalanx

Correct answer: An osteochondral fragment typically arising from the dorsal proximal rim of the middle phalanx

Dorsal chip fractures at the pastern joint are osteochondral fragments typically arising from the dorsal proximal rim of the middle phalanx, removed arthroscopically.

Question 24: On a lateral thoracic radiograph, 'sternal contact' of the heart is increased in which cardiac condition?

Left atrial enlargement
Pulmonary hypertension
Pericardial effusion
Right ventricular enlargement (Correct answer)

Correct answer: Right ventricular enlargement

Right ventricular enlargement causes the heart to shift cranioventrally, increasing its contact with the sternum on the lateral view.

Question 25: A 4-year-old intact female Doberman Pinscher presents with acute collapse. Echocardiography reveals a large hypoechoic space surrounding the heart with compression of the right atrium during diastole. The most appropriate NEXT imaging step to identify the underlying etiology is:

CT angiography of the thorax with IV contrast after stabilization via pericardiocentesis (Correct answer)
Radiographic measurement of the vertebral heart scale (VHS) to differentiate effusion from cardiomegaly
Repeat echocardiography in 48 hours following pericardiocentesis to assess for mass lesion
Contrast-enhanced ultrasound (CEUS) of the right auricular appendage after pericardiocentesis

Correct answer: CT angiography of the thorax with IV contrast after stabilization via pericardiocentesis

In a Doberman with cardiac tamponade, after life-saving pericardiocentesis, CT angiography with IV contrast is the superior next step for identifying the etiology. Hemangiosarcoma of the right auricle and heart base tumors (chemodectoma) are the most common causes. CT provides superior soft tissue characterization, detects small auricular masses invisible on echocardiography (especially post-pericardiocentesis when fluid is removed), and evaluates for concurrent thoracic or abdominal metastatic disease. CEUS can visualize auricular masses but has more limited anatomic coverage. Repeat echo alone after 48 hours is inferior — CT is now the standard of care for neoplastic pericardial effusion workup.

Question 26: An alpaca presents with progressive weight loss, bottle jaw, and anemia. Fecal flotation reveals strongyle-type eggs. Which anthelmintic class is most commonly used as first-line therapy in camelids with suspected Haemonchus?

Macrocyclic lactones (e.g., ivermectin) (Correct answer)
Imidazothiazoles (e.g., levamisole)
Salicylanilides (e.g., closantel)
Benzimidazoles (e.g., fenbendazole)

Correct answer: Macrocyclic lactones (e.g., ivermectin)

Macrocyclic lactones such as ivermectin are commonly used first-line in camelids for Haemonchus contortus, though resistance monitoring via fecal egg count reduction tests is recommended.

Question 27: What is the primary mechanism by which ivermectin kills parasites?

Blocks tubulin polymerization
Inhibits acetylcholinesterase
Potentiates glutamate-gated chloride channels causing paralysis (Correct answer)
Disrupts parasite cell membrane integrity

Correct answer: Potentiates glutamate-gated chloride channels causing paralysis

Ivermectin potentiates glutamate-gated chloride channels in invertebrate nerve and muscle cells, causing hyperpolarization, paralysis, and death of the parasite.

Question 28: A 12-year-old Warmblood sport horse presents with subtle right forelimb lameness that worsens significantly after palmar digital nerve blocks but does not improve with abaxial sesamoid blocks. Radiographs of the foot are unremarkable. Which diagnosis best explains this paradoxical worsening?

Navicular syndrome with concurrent palmar foot pain
Collateral desmitis of the distal interphalangeal joint
Deep digital flexor tendon tear proximal to the pastern
Neurectomy effect unmasking proximal limb pain (Correct answer)

Correct answer: Neurectomy effect unmasking proximal limb pain

Paradoxical worsening after a distal nerve block occurs when the blocked region was providing some compensatory proprioceptive input or the horse was guarding against distal pain in a way that partially stabilized a more proximal lesion. By abolishing the distal pain signal, the proximal pathology (which the abaxial sesamoid block does not reach) becomes the dominant pain source and lameness worsens. This 'unmasking' phenomenon is a recognized pitfall in sequential perineural diagnostic analgesia.

Question 29: A 9-year-old cat with a 6-month history of recurrent upper respiratory signs, bilateral corneal sequestra, and chronic gingivostomatitis has positive FHV-1 PCR on conjunctival swab. The owner asks about antiviral therapy. Which statement regarding famciclovir use in cats is MOST accurate?

Famciclovir should be avoided in cats because feline cytochrome P450 enzymes convert it to a nephrotoxic methylated metabolite
Famciclovir requires concurrent l-lysine supplementation to competitively inhibit viral DNA polymerase activity synergistically
Famciclovir is effective because cats efficiently convert it to penciclovir via intestinal and hepatic ester hydrolases, achieving therapeutic penciclovir concentrations (Correct answer)
Acyclovir is preferred over famciclovir in cats because famciclovir has poor oral bioavailability due to incomplete first-pass intestinal conversion

Correct answer: Famciclovir is effective because cats efficiently convert it to penciclovir via intestinal and hepatic ester hydrolases, achieving therapeutic penciclovir concentrations

Famciclovir is the antiviral of choice for FHV-1 in cats precisely because cats CAN efficiently metabolize famciclovir (the prodrug) to penciclovir (the active compound) via intestinal ester hydrolases and hepatic aldehyde oxidase — unlike dogs, which do so poorly. This is the opposite of the situation with acyclovir: acyclovir has low bioavailability in cats and is potentially nephrotoxic at higher doses due to renal tubular precipitation. Famciclovir at 40–90 mg/kg PO q8–12h achieves therapeutic penciclovir levels. l-Lysine does NOT work synergistically with famciclovir — its proposed mechanism (arginine competition) is now considered clinically ineffective by current evidence.

Question 30: On a lateral abdominal radiograph of a vomiting 8-year-old Shih Tzu, you identify a mineralized opacity within the pyloric antrum. The opacity has a faceted, angular appearance with multiple distinct densities on the orthogonal view. What is the most likely diagnosis?

Choleliths that have migrated through a biliary-enteric fistula into the pylorus (Correct answer)
Gastric foreign body composed of multiple compacted mineral fragments (enterolith)
Dystrophic mineralization within a chronic mural hematoma
Neoplastic mineralization within a pyloric adenocarcinoma

Correct answer: Choleliths that have migrated through a biliary-enteric fistula into the pylorus

Faceted, angular, radiopaque calculi within the stomach or pylorus with distinct layering/multiple density facets are characteristic of choleliths (gallstones) that have migrated into the GI tract via a cholecystoduodenal or biliary-enteric fistula — a rare but well-documented condition called Bouveret syndrome (gastric outlet obstruction by a gallstone). The faceted morphology and mixed mineral densities (mixed cholesterol/calcium bilirubinate composition) are hallmarks of cholecystolithiasis. Simple enteroliths tend to be round/oval and form distally. Neoplastic mineralization is typically amorphous and associated with a soft tissue mass.

Question 31: A 4-week-old foal presents with a carpal valgus deformity of the right forelimb. The deviation is moderate and has not improved with stall rest and corrective hoof trimming. What is the most appropriate next step in managing this case to achieve a successful outcome?

Perform periosteal stripping on the medial aspect of the distal radius. (Correct answer)
Continue conservative management as the growth plates will close soon.
Recommend euthanasia due to a poor prognosis for athletic function.
Perform transphyseal bridging on the medial aspect of the distal radius.

Correct answer: Perform periosteal stripping on the medial aspect of the distal radius.

For a moderate carpal valgus (knock-kneed) deformity in a 4- to 6-week-old foal that is not responding to conservative therapy, periosteal stripping (also called a hemicircumferential periosteal transection and elevation) on the concave side (medial aspect) of the limb is the appropriate surgical intervention. This procedure is thought to accelerate growth on the slower-growing side of the physis. Transphyseal bridging is used on the convex (lateral) side to slow growth and is typically reserved for more severe deformities or older foals. Continuing conservative management is inappropriate as the optimal window for surgical correction is during rapid growth.

Question 32: A 9-year-old cat presents with acute collapse, jugular distension, muffled heart sounds, and pulsus paradoxus. Echocardiography confirms pericardial effusion with right atrial collapse. Which etiology is most common for pericardial effusion causing tamponade in cats, and how does it differ from dogs?

Feline infectious peritonitis (FIP) causing exudative effusion; dogs more commonly have hemangiosarcoma (Correct answer)
Lymphoma infiltrating the pericardium; dogs most commonly have right atrial hemangiosarcoma
Thymoma compressing cardiac structures; dogs more commonly develop mesothelioma
Hypertrophic cardiomyopathy with congestive heart failure extending to pericardium; dogs primarily have idiopathic effusion

Correct answer: Feline infectious peritonitis (FIP) causing exudative effusion; dogs more commonly have hemangiosarcoma

In cats, FIP is the most common cause of pericardial effusion producing cardiac tamponade, causing an exudative high-protein effusion due to coronavirus-mediated vasculitis. In dogs, right atrial hemangiosarcoma and idiopathic pericardial effusion dominate. This species difference is clinically important because treatment, prognosis, and diagnostics differ substantially. FIP effusion in cats characteristically has high protein content (>3.5 g/dL) and a yellow, viscous appearance with Rivalta test positivity.

Question 33: Which flea and tick preventive acts as a selective antagonist of insect GABA-gated chloride channels?

Selamectin
Fipronil (Correct answer)
Imidacloprid
Spinosad

Correct answer: Fipronil

Fipronil selectively blocks GABA-gated chloride channels in insects and arachnids, causing CNS hyperexcitability and death; it has low affinity for mammalian receptors.

Question 34: A veterinarian is designing a Johne's disease (paratuberculosis) test-and-cull program for a 500-cow closed dairy herd. The herd-level prevalence is estimated at 8%. The diagnostic lab offers two ELISA tests: Test A (sensitivity 45%, specificity 99%) and Test B (sensitivity 28%, specificity 99.8%). The producer's primary goal is to eliminate all infected animals without culling excessive false-positives. Which testing strategy is most appropriate?

Use Test A alone annually, because its higher sensitivity identifies more infected animals per test cycle
Use Test B alone annually, because its higher specificity minimizes false-positive culls at this prevalence
Use Test A as a screen, then confirm positives with Test B in series, to maximize both sensitivity and specificity (Correct answer)
Use fecal PCR as the primary test rather than ELISA, because ELISA sensitivity is inadequate below 10% prevalence

Correct answer: Use Test A as a screen, then confirm positives with Test B in series, to maximize both sensitivity and specificity

At 8% prevalence, even a 99% specific test yields a positive predictive value (PPV) of approximately 82% for Test A and 97% for Test B when used alone. However, Test A's sensitivity (45%) catches more true positives per annual round. Using Test A as a screen (higher sensitivity captures more infected animals) and Test B as a confirmatory test in series (very high specificity eliminates most false positives) optimizes the program: sensitivity of the series is limited by Test A (acceptable), but specificity approaches Test B's 99.8%, making PPV very high and preventing unnecessary culls. Fecal PCR is valuable but not superior in all low-prevalence settings and is more expensive per sample; it is not 'always preferred' below 10% prevalence. The series testing strategy is the standard of practice for Johne's control programs.

Question 35: A 5-year-old intact female Boxer presents for abdominal radiographs due to acute vomiting. Radiographs reveal a markedly distended, gas-filled stomach with a soft tissue band ('shelf sign') in the mid-gastric region and the pylorus positioned to the left of midline on the VD projection. A small amount of free peritoneal gas is also noted. Which combination of conditions does this radiographic constellation represent?

Gastric dilatation-volvulus (GDV) with gastric perforation (Correct answer)
Simple gastric dilatation with concurrent pneumoperitoneum from recent abdominocentesis
Hiatal hernia with secondary pneumoperitoneum
Gastric foreign body with pyloric obstruction and diaphragmatic hernia

Correct answer: Gastric dilatation-volvulus (GDV) with gastric perforation

The combination of marked gastric gas distension, a 'shelf sign' (also called the 'double bubble' or compartmentalization created by torsion of the gastric wall), and pyloric displacement to the LEFT of midline on the VD view is pathognomonic for GDV. In GDV, the pylorus rotates clockwise (viewed from the patient's caudal aspect) to end up cranial and to the left. The presence of free peritoneal gas (pneumoperitoneum) indicates gastric rupture/perforation, which is a grave complication confirming the need for immediate surgical intervention. This constellation—GDV + perforation—carries the worst prognosis.

Question 36: Air sac mites (Sternostoma tracheacolum) most commonly cause respiratory disease in which group of birds?

Domestic poultry
Psittacines (parrots)
Waterfowl
Canaries and finches (Correct answer)

Correct answer: Canaries and finches

Air sac mites primarily affect Passeriformes such as canaries and finches, causing respiratory distress and the 'going light' syndrome.

Question 37: During a routine splenectomy in a 6-year-old DSH cat for splenic mast cell tumor, the surgeon encounters unexpected difficulty controlling hemorrhage from the short gastric vessels. Intraoperatively, the cat develops a sudden drop in systolic BP to 55 mmHg, bradycardia (HR 48 bpm), and becomes unresponsive. Which drug combination is MOST appropriate as the FIRST intervention?

Atropine 0.04 mg/kg IV + epinephrine 0.01 mg/kg IV (Correct answer)
Dopamine CRI at 5 µg/kg/min
Vasopressin 0.4 units/kg IV + atropine 0.02 mg/kg IV
Epinephrine 0.01 mg/kg IV alone

Correct answer: Atropine 0.04 mg/kg IV + epinephrine 0.01 mg/kg IV

This presentation — profound hypotension + bradycardia + unresponsiveness during mast cell tumor manipulation — is consistent with a massive histamine/tryptase release event (anaphylaxis or mast cell degranulation crisis). The combination of hypotension AND bradycardia (rather than the reflex tachycardia of simple hemorrhage) with intraoperative mast cell tumor handling strongly implicates degranulation. Atropine addresses the vagotonic bradycardia, and epinephrine is the drug of choice for anaphylaxis — it reverses bronchospasm, causes vasoconstriction (α1), and positive chronotropy/inotropy (β1/β2). Vasopressin is a second-line vasopressor but does not address the bradycardia or anaphylactic mechanism. A dopamine CRI has too slow an onset in this acute crisis.

Question 38: A state veterinarian is investigating a cluster of human Salmonella Heidelberg cases linked to a poultry processing facility. Whole-genome sequencing (WGS) reveals the human isolates match a strain found in broilers from Farm A, but the processing plant draws from 14 farms. Which epidemiological concept best explains why WGS alone is insufficient to establish regulatory action against Farm A without additional trace-back data?

The ecological fallacy arising from aggregating farm-level data
Berkson's bias introduced by hospitalized case selection
The difference between statistical association and attributable source under legal burden-of-proof standards
Misclassification of exposure due to cross-contamination during slaughter (Correct answer)

Correct answer: Misclassification of exposure due to cross-contamination during slaughter

Cross-contamination during slaughter is the critical confounder. A single processing line can transfer a strain from one farm's flock to carcasses originating from other farms, meaning WGS identity between human cases and Farm A broilers could reflect contamination at the plant rather than Farm A as the true reservoir. Without lot-specific trace-back confirming the matched carcasses came exclusively from Farm A and were not co-mingled on the same line, regulatory action targeting that farm specifically is scientifically unsupported. The other options describe real biases but are not the primary mechanistic explanation in a multi-farm slaughter scenario.

Question 39: A 3-year-old Thoroughbred filly sustained a non-displaced condylar fracture of the third metacarpus during a race. What is the recommended surgical treatment to allow return to racing?

Stall rest with a full limb cast for 12 weeks
Internal fixation with cortical lag screws placed perpendicular to the fracture line (Correct answer)
Condylar resection
Robert Jones bandage and controlled exercise

Correct answer: Internal fixation with cortical lag screws placed perpendicular to the fracture line

Non-displaced condylar fractures of the third metacarpus are best managed with internal fixation using cortical lag screws to provide interfragmentary compression and allow earlier return to training.

Question 40: A 12-year-old Hanoverian mare develops acute severe lameness 48 hours after a routine intra-articular corticosteroid injection in the stifle. The joint is severely swollen, warm, and painful. Synoviocentesis is performed. Which synovial fluid finding would most strongly indicate post-injection septic arthritis rather than a corticosteroid flare?

WBC of 3,000/μL with 60% mononuclear cells
Xanthochromic fluid with red blood cells
WBC of 60,000/μL with 95% neutrophils and positive bacterial culture (Correct answer)
Slightly elevated protein with no change in cell count

Correct answer: WBC of 60,000/μL with 95% neutrophils and positive bacterial culture

Post-injection septic arthritis is confirmed by markedly elevated WBC (>30,000/μL) with predominantly neutrophils and positive bacterial culture, distinguishing it from a transient corticosteroid flare.

Question 41: Which drug used in cattle to synchronize estrus can cause luteolysis by acting on the corpus luteum?

Progesterone
Estradiol
GnRH
Prostaglandin F2α (PGF2α) (Correct answer)

Correct answer: Prostaglandin F2α (PGF2α)

Prostaglandin F2α causes regression of the corpus luteum (luteolysis), leading to a decrease in progesterone and allowing the next follicular wave to result in estrus.

Question 42: A gilt in a farrow-to-finish operation develops diamond-shaped, raised, red skin lesions over the trunk 2 days after moving to the breeding barn. The most appropriate treatment is:

Ivermectin SC and topical antifungal
Enrofloxacin IM and corticosteroids
Penicillin G IM, NSAIDs, and isolation (Correct answer)
Florfenicol IM and supportive care

Correct answer: Penicillin G IM, NSAIDs, and isolation

Diamond-shaped urticarial skin lesions (diamond skin disease) are classic for Erysipelothrix rhusiopathiae infection in pigs. Erysipelas responds well to penicillin G; NSAIDs reduce fever and inflammation. Corticosteroids are contraindicated in bacteremic animals; enrofloxacin has poor activity against Erysipelothrix.

Question 43: A 5-year-old Siamese cat is presented for a chronic, intermittent cough and occasional wheezing. Thoracic radiographs are performed. Which of the following radiographic patterns is most consistent with a diagnosis of feline asthma?

A prominent bronchial pattern, characterized by 'doughnuts' and 'tramlines', with evidence of lung hyperinflation. (Correct answer)
Enlarged, tortuous pulmonary arteries and right-sided cardiomegaly.
A patchy alveolar pattern concentrated in the cranioventral lung lobes.
A diffuse, unstructured interstitial pattern with prominent pulmonary veins.

Correct answer: A prominent bronchial pattern, characterized by 'doughnuts' and 'tramlines', with evidence of lung hyperinflation.

Feline asthma is an inflammatory condition of the lower airways. Radiographically, this manifests as a prominent bronchial pattern due to the accumulation of inflammatory cells around the airways. These thickened bronchial walls are seen as 'doughnuts' (end-on view) and 'tramlines' (long-axis view). Air trapping due to bronchoconstriction can also lead to lung hyperinflation.

Question 44: Anaplasmosis in cattle is transmitted primarily by which vector in the US?

Aedes aegypti mosquitoes
Stomoxys calcitrans stable flies
Haematobia irritans horn flies
Dermacentor andersoni and Dermacentor variabilis ticks (Correct answer)

Correct answer: Dermacentor andersoni and Dermacentor variabilis ticks

Anaplasma marginale is transmitted by Dermacentor tick species in the US, though mechanical transmission by biting flies and blood-contaminated instruments also occurs.

Question 45: A 9-year-old spayed female Labrador Retriever presents with a 4-month history of progressive rear limb weakness. The owner reports the dog can walk but stumbles, especially on slippery floors, and has difficulty rising. On neurologic exam, you observe proprioceptive deficits in both pelvic limbs (worse on the right), preserved but slightly diminished patellar reflexes bilaterally, and normal perineal reflex and anal tone. MRI of the thoracolumbar spine is unremarkable. Which diagnosis best explains this constellation of findings?

Myasthenia gravis (focal form)
Lumbosacral stenosis (cauda equina syndrome)
Fibrocartilaginous embolism at T12-T13
Degenerative myelopathy (Correct answer)

Correct answer: Degenerative myelopathy

Degenerative myelopathy (DM) classically presents as a slowly progressive, non-painful upper motor neuron (UMN) spastic paraparesis in older large-breed dogs (especially Labradors, GSDs, and Boxers), with proprioceptive ataxia and no sensory deficits. A critical diagnostic clue is that MRI is normal early in the disease — DM is a clinical and genetic diagnosis (SOD1 mutation) confirmed histopathologically. FCE would present acutely, not over 4 months. Cauda equina syndrome causes hyporeflexia, tail and perineal deficits, and lumbosacral pain. Focal MG causes megaesophagus/regurgitation, not proprioceptive deficits.

Question 46: Ultrasound-guided fine-needle aspiration of a splenic mass in a 10-year-old Golden Retriever yields a non-diagnostic sample. On ultrasound, the mass is a 4-cm, cavitary, mixed echogenicity lesion. Contrast-enhanced ultrasound (CEUS) shows rapid arterial enhancement followed by marked washout in the late portal phase, resulting in a 'Swiss cheese' enhancement pattern. Which splenic pathology does this CEUS pattern MOST strongly suggest?

Nodular hyperplasia
Splenic hematoma
Splenic hemangiosarcoma (Correct answer)
Splenic hemangioma

Correct answer: Splenic hemangiosarcoma

Hemangiosarcoma on CEUS characteristically shows rapid, heterogeneous arterial phase enhancement (due to abnormal tumor vasculature) followed by early and marked washout during the portal/late phase—producing the so-called 'Swiss cheese' or heterogeneous enhancement pattern with hypoechoic regions corresponding to necrosis or hemorrhage. Hemangiomas also enhance early but tend to show more uniform, persistent enhancement ('fill-in' pattern). Nodular hyperplasia shows isoenhancement or mild hyperenhancement without early washout. Hematomas show little to no vascular enhancement. Early washout is the key discriminator favoring malignancy.

Question 47: A 9-year-old cat presents with hypercalcemia (total Ca 14.2 mg/dL), weight loss, and peripheral lymphadenopathy. Which condition is most likely?

Primary hyperparathyroidism
Idiopathic hypercalcemia
Hypervitaminosis D
Lymphoma (Correct answer)

Correct answer: Lymphoma

Lymphoma is the most common cause of hypercalcemia of malignancy in cats, mediated by PTHrP secretion.

Question 48: Histologic examination of a canine skin biopsy shows epidermal hyperplasia, parakeratosis, Munro microabscesses (neutrophil collections in the stratum corneum), and perivascular lymphocytic infiltrate in the superficial dermis. This pattern is most consistent with:

Psoriasiform-lichenoid dermatitis (Correct answer)
Pemphigus foliaceus
Mast cell tumor with epidermal reaction
Superficial bacterial pyoderma

Correct answer: Psoriasiform-lichenoid dermatitis

Psoriasiform-lichenoid dermatitis in dogs is characterized histologically by epidermal hyperplasia (psoriasiform), parakeratosis, intracorneal neutrophil accumulations (Munro microabscesses), and a lichenoid (interface) or superficial perivascular infiltrate. Pemphigus foliaceus shows acantholytic cells and subcorneal pustules; pyoderma shows suppurative folliculitis.

Question 49: A herd of stocker cattle develops red-water disease (bacillary hemoglobinuria). Which organism and predisposing factor is responsible?

Clostridium novyi type A, wound contamination
Clostridium perfringens type C, high-grain diet
Clostridium haemolyticum, liver fluke migration (Correct answer)
Clostridium septicum, skin wounds in wet conditions

Correct answer: Clostridium haemolyticum, liver fluke migration

Bacillary hemoglobinuria is caused by C. haemolyticum (C. novyi type D), which proliferates in anaerobic zones created by migrating Fasciola hepatica liver flukes.

Question 50: A horse with chronic forelimb lameness shows 'pointing' at rest — standing with the affected limb extended cranially. This posture is MOST commonly associated with:

Coffin joint arthritis
Laminitis
Navicular syndrome (Correct answer)
Extensor tendon injury

Correct answer: Navicular syndrome

Pointing at rest is a classic postural sign of navicular syndrome, as the horse reduces weight on the heel to relieve pressure on the navicular apparatus.

Question 51: Which finding on effusion fluid analysis is most consistent with FIP rather than cardiac or neoplastic effusion?

Hemorrhagic effusion with numerous erythrocytes
Exudate with low protein and low cell count
Transudate with protein <25 g/L
Straw-colored viscous exudate with protein >35 g/L and low cell count (Correct answer)

Correct answer: Straw-colored viscous exudate with protein >35 g/L and low cell count

FIP effusion is typically a viscous, straw-colored exudate with high protein (>35 g/L) but surprisingly low cell counts, yielding a high Rivalta test result.

Question 52: A herd of 30 beef cow-calf pairs is experiencing an outbreak of bloody diarrhea in calves 5–21 days of age. Mortality has reached 30% despite oral electrolyte therapy. Post-mortem findings include hemorrhagic enteritis of the jejunum and ileum with villous necrosis and blunting. Gram-positive, spore-forming rods are visualized on intestinal smear. PCR of intestinal contents is positive for NetB toxin gene. Which pathogen and the toxin most responsible for villous destruction are correctly identified?

Clostridium difficile; toxin B
Clostridium perfringens Type A; alpha toxin
Clostridium perfringens Type D; epsilon toxin
Clostridium perfringens Type C; beta toxin (Correct answer)

Correct answer: Clostridium perfringens Type C; beta toxin

NetB toxin is produced by Clostridium perfringens Type C and is a pore-forming toxin. However, the primary virulence factor in Type C hemorrhagic enteritis of neonatal calves is beta toxin (cpb gene), which causes severe necrotizing enteritis by disrupting intestinal epithelium. Beta toxin is protease-sensitive, which is why it preferentially affects neonates lacking tryptic activity. Type A causes mild diarrhea via alpha toxin; Type D causes pulpy kidney/edema disease via epsilon toxin; C. difficile produces toxins A and B in a different syndrome. The NetB gene in the PCR confirms Type C.

Question 53: A pig farm reports sudden death in 3-week-old piglets with gross necropsy findings of fibrinous polyserositis, arthritis, and meningitis. The most likely causative agent is:

Actinobacillus pleuropneumoniae
Mycoplasma hyorhinis
Streptococcus suis type 2
Haemophilus parasuis (Glässer's disease) (Correct answer)

Correct answer: Haemophilus parasuis (Glässer's disease)

Haemophilus parasuis causes Glässer's disease in young pigs, characterized by fibrinous polyserositis (peritonitis, pleuritis, pericarditis), arthritis, and meningitis at 3–8 weeks of age.

Question 54: Gabapentin is increasingly used in cats for anxiety and pain. Which pharmacokinetic property is clinically important in feline dosing?

It is renally excreted unchanged and dose must be reduced with renal insufficiency (Correct answer)
It is highly protein-bound and interacts with NSAIDs
It requires CYP2D6 for activation to its active form
It undergoes extensive first-pass hepatic metabolism

Correct answer: It is renally excreted unchanged and dose must be reduced with renal insufficiency

Gabapentin is eliminated renally with minimal hepatic metabolism, so dose intervals must be extended in cats with chronic kidney disease.

Question 55: A 12-year-old Warmblood sport horse presents with subtle, intermittent right forelimb lameness that worsens on soft footing and improves on firm ground. Flexion tests are negative. Diagnostic analgesia of the distal limb fails to improve the lameness. MRI reveals focal cartilage erosion on the palmar aspect of the lateral trochlear ridge of the distal radius. Which condition does this BEST describe?

Osteochondritis dissecans of the distal radial carpal bone
Subchondral bone cyst of the proximal third carpal bone
Palmar osteochondral disease (POD) of the radiocarpal joint (Correct answer)
Distal interphalangeal joint synovitis

Correct answer: Palmar osteochondral disease (POD) of the radiocarpal joint

Palmar osteochondral disease (POD), also called 'sport horse carpus,' involves cartilage erosion and subchondral bone pathology on the palmar aspects of the radiocarpal and intercarpal joints. It is characteristically worse on soft footing because greater fetlock extension loads the palmar carpal structures. Distal limb analgesia does not block this region, explaining the negative response. MRI is often required for definitive diagnosis as radiographs may be unremarkable early in the disease.

Question 56: Which opioid is most appropriate for epidural administration in dogs to provide extended postoperative analgesia with minimal motor blockade?

Morphine (Correct answer)
Meperidine
Butorphanol
Fentanyl

Correct answer: Morphine

Preservative-free morphine administered epidurally provides long-duration analgesia (12–24 hours) with minimal motor effects due to its hydrophilicity.

Question 57: A 5-year-old Thoroughbred racehorse undergoes nuclear scintigraphy for investigation of right forelimb lameness that has not localized with nerve blocks. The bone scan shows markedly increased radiopharmaceutical uptake (IRU) in the mid-diaphysis of the right third metacarpal bone on the lateral cortex. What is the most appropriate next diagnostic step to characterize this lesion before formulating a treatment plan?

Ultrasonography of the lateral aspect of the cannon bone to evaluate the periosteum
Repeat nuclear scintigraphy in 4 weeks to assess progression of uptake
MRI of the distal forelimb in the standing horse to rule out concurrent navicular disease
CT of the right forelimb to characterize cortical integrity and quantify stress fracture propagation (Correct answer)

Correct answer: CT of the right forelimb to characterize cortical integrity and quantify stress fracture propagation

Focal high IRU in the diaphyseal cortex of the third metacarpus in a racehorse is highly suspicious for a stress fracture, which carries risk of complete catastrophic fracture if the horse is exercised. CT provides detailed cross-sectional characterization of cortical integrity, fracture line orientation, and propagation depth — information critical to differentiating a stable incomplete cortical stress fracture from one approaching propagation, which directly determines surgical vs. conservative management. Repeat scintigraphy delays diagnosis without adding anatomical detail. Ultrasonography evaluates periosteal soft tissue but cannot adequately assess cortical fracture geometry. Standing MRI of the distal limb does not image the mid-diaphysis.

Question 58: Which radiographic sign on a lateral thoracic view indicates right-sided cardiomegaly in a dog?

Dorsal displacement of the trachea
Widening of the caudal vena cava shadow
Increased sternal contact (more than 3 sternal segments) (Correct answer)
Loss of the cranial waist on the VD view

Correct answer: Increased sternal contact (more than 3 sternal segments)

Right heart enlargement causes the cardiac silhouette to contact more sternal segments than normal (typically more than 3), displacing the apex ventrally.

Question 59: Which of the following medications is a potent, broad-spectrum antiemetic that functions by antagonizing neurokinin-1 (NK-1) receptors in the central vomiting center?

Famotidine
Maropitant (Correct answer)
Metoclopramide
Ondansetron

Correct answer: Maropitant

Maropitant is a neurokinin-1 (NK-1) receptor antagonist. It works by blocking the binding of Substance P, a key neurotransmitter in the emetic pathway, at NK-1 receptors located in the vomiting center and the chemoreceptor trigger zone. This mechanism makes it highly effective against vomiting from both central and peripheral stimuli. Ondansetron is a serotonin (5-HT3) antagonist, metoclopramide is primarily a dopamine (D2) antagonist, and famotidine is an H2-receptor antagonist used to reduce stomach acid.

Question 60: During colic surgery, you identify a large colon displacement in which the left dorsal colon is displaced laterally under the spleen and nephrosplenic ligament. What is this condition called and what is the initial non-surgical treatment?

Right dorsal displacement; phenylephrine and rolling
Cecal volvulus; nasogastric decompression
Right dorsal displacement; heparin therapy
Left dorsal displacement (nephrosplenic entrapment); phenylephrine and rolling (Correct answer)

Correct answer: Left dorsal displacement (nephrosplenic entrapment); phenylephrine and rolling

Nephrosplenic (left dorsal) displacement involves the colon entrapped over the nephrosplenic ligament and can often be corrected non-surgically using phenylephrine to contract the spleen combined with controlled rolling under general anesthesia.

Question 61: On abdominal ultrasound, an anechoic structure with distal acoustic enhancement in the kidney is MOST consistent with:

Renal abscess
Simple renal cyst (Correct answer)
Nephrolithiasis
Transitional cell carcinoma

Correct answer: Simple renal cyst

Simple cysts are anechoic with a thin wall and show distal acoustic enhancement due to the lack of sound attenuation by fluid.

Question 62: A 6-year-old bearded dragon (Pogona vitticeps) presents with anorexia, lethargy, and swollen limbs. Radiographs show lytic bone lesions and periosteal proliferation. Bloodwork reveals marked heterophilia and a PCV of 18%. Cytology of a fine-needle aspirate from a swollen limb reveals large, round organisms with a clear halo and a basophilic nucleus consistent with yeast. Which diagnosis and treatment is most appropriate?

Disseminated Ophidiomyces ophiodiicola — voriconazole monotherapy
Disseminated Devriesea agamarum infection — enrofloxacin and supportive care
Chrysosporium anamorph of Nannizziopsis vriesii (CANV) infection — itraconazole and surgical debridement (Correct answer)
Basidiobolus ranarum infection — amphotericin B and potassium iodide

Correct answer: Chrysosporium anamorph of Nannizziopsis vriesii (CANV) infection — itraconazole and surgical debridement

CANV (Chrysosporium anamorph of Nannizziopsis vriesii) is a primary fungal pathogen of agamid lizards, including bearded dragons, causing deep mycosis with lytic bone lesions, skin ulceration, and systemic dissemination. The large round yeast with a clear halo on cytology is characteristic. Treatment requires long-term itraconazole combined with aggressive surgical debridement of affected tissue. Devriesea agamarum is a bacterial pathogen. Ophidiomyces is a snake fungal disease. Basidiobolus causes GI infections in reptiles but has a different clinical presentation.

Question 63: Radiographs of a 4-year-old Warmblood show osteochondral fragments at the dorsal aspect of the proximal interphalangeal (pastern) joint. The horse has mild lameness improved by intra-articular analgesia. What is the recommended treatment?

Intra-articular sodium hyaluronate injections only
Systemic NSAIDs and box rest for 6 months
Arthroscopic removal of osteochondral fragments (Correct answer)
Pastern joint arthrodesis

Correct answer: Arthroscopic removal of osteochondral fragments

Osteochondral fragments at the pastern joint are best treated by arthroscopic removal, which provides the most reliable return to athletic function.

Question 64: A dairy manager reports a sudden increase in the herd's bulk tank somatic cell count (SCC). The majority of cows appear clinically normal. What is the most effective and practical initial step to identify the individual cows contributing to the high SCC?

Perform a California Mastitis Test (CMT) on milk from all lactating cows. (Correct answer)
Cull all cows with a previous history of clinical mastitis.
Culture a milk sample from the bulk tank to identify the causative pathogen.
Immediately treat all lactating cows with a broad-spectrum intramammary antibiotic.

Correct answer: Perform a California Mastitis Test (CMT) on milk from all lactating cows.

The California Mastitis Test (CMT) is a rapid, cow-side test that provides a semi-quantitative estimate of the SCC for individual cows (or quarters), allowing for the quick identification of animals with subclinical mastitis. While bulk tank culture identifies pathogens, it doesn't pinpoint the infected cows. Treating the whole herd is not cost-effective and is poor antimicrobial stewardship. Culling is a drastic measure used for chronically infected cows, not as an initial diagnostic step.

Question 65: A ferret with insulinoma is being treated medically. Which drug is used to increase blood glucose by inhibiting insulin secretion?

Phenobarbital
Diazoxide (Correct answer)
Methimazole
Prednisolone

Correct answer: Diazoxide

Diazoxide inhibits pancreatic insulin secretion and promotes glycogenolysis, making it useful for managing hypoglycemia in ferrets with insulinoma.

Question 66: A 2-year-old intact female sugar glider (Petaurus breviceps) presents with a 1 cm, firm, non-painful mass on the dorsal midline of the head. The owner reports the mass appeared over 2 weeks. On exam, the animal is bright and alert with no neurologic signs. Cytology of a fine-needle aspirate reveals cells with abundant pale cytoplasm, round nuclei, and prominent nucleoli in a proteinaceous background. What is the most likely diagnosis?

Lymphosarcoma with cutaneous metastasis
Abscess secondary to conspecific bite wound
Dermatofibrosarcoma of the scalp secondary to repetitive self-trauma
Scent gland adenocarcinoma arising from the frontofrontal gland (Correct answer)

Correct answer: Scent gland adenocarcinoma arising from the frontofrontal gland

Male sugar gliders have a prominent frontofrontal (forehead) scent gland, but females can develop neoplasia of the same glandular tissue. Adenocarcinoma of the frontofrontal scent gland presents as a rapidly growing firm mass on the dorsal midline of the head. Cytology typically reveals epithelial cells with abundant pale cytoplasm and prominent nucleoli in a proteinaceous background consistent with glandular secretory tissue gone malignant. Dermatofibrosarcoma and lymphoma are less likely without inflammatory history or systemic signs. An abscess would typically show degenerate neutrophils and bacteria.

Question 67: A cockatiel presents with symmetrical feather loss over the head and neck, with pin feathers that appear hemorrhagic and dystrophic. The most appropriate diagnostic test is:

PCR for Psittacine Beak and Feather Disease virus (Correct answer)
Bacterial culture of feather follicle
Complete blood count
Fungal culture

Correct answer: PCR for Psittacine Beak and Feather Disease virus

Psittacine Beak and Feather Disease (PBFD) caused by circovirus is best diagnosed via PCR testing and presents with dystrophic feathers and immunosuppression.

Question 68: A cat with hypertrophic cardiomyopathy requires anesthesia. Which inhalant anesthetic is generally preferred for its cardiovascular stability in cats with cardiac disease?

Isoflurane
Desflurane
Halothane
Sevoflurane (Correct answer)

Correct answer: Sevoflurane

Sevoflurane has the least negative cardiovascular effects and most rapid induction/recovery among currently available inhalants, making it preferred in feline cardiac patients.

Question 69: Which antiviral drug has been shown to induce remission of FIP caused by FCoV mutation (FIPV) in clinical trials and is now widely used off-label?

Ribavirin
Interferon-omega
GS-441524 (nucleoside analog) (Correct answer)
Famciclovir

Correct answer: GS-441524 (nucleoside analog)

GS-441524, an adenosine nucleoside analog, inhibits FCoV replication and has shown >85% sustained remission rates in cats with wet and dry FIP in clinical studies.

Question 70: A 3-year-old indoor cat presents with pleural effusion, hyperglobulinemia (total protein 10.2 g/dL), and a pleural fluid albumin-to-globulin ratio of 0.3. FIP coronavirus PCR on the effusion is positive. Which additional finding would MOST strongly support effusive FIP over other causes of pleural effusion?

Pleural fluid neutrophilia >85% with a degenerate left shift
Positive FCoV antibody titer >1:3200 on serum ELISA
Rivalta test positive on the effusion with protein >3.5 g/dL and cell count <5,000 cells/µL
Serum alpha-1 acid glycoprotein (AGP) >1,500 µg/mL (Correct answer)

Correct answer: Serum alpha-1 acid glycoprotein (AGP) >1,500 µg/mL

Serum alpha-1 acid glycoprotein (AGP) >1,500 µg/mL has high sensitivity and specificity for FIP in cats with compatible clinical signs. While the Rivalta test is supportive of FIP-type effusion, it is not specific enough alone. High FCoV titers indicate exposure but not necessarily FIP (many healthy cats have high titers). Neutrophilic effusion with degenerate shift suggests bacterial pyothorax. AGP is an acute-phase protein markedly elevated in FIP and serves as one of the most diagnostically useful adjunct markers.

Question 71: Which radiographic sign is MOST characteristic of a diaphragmatic hernia in a dog?

Loss of diaphragmatic outline with abdominal organs in the thorax (Correct answer)
Pleural fissure lines at the lung margins
Increased sternal contact of the cardiac silhouette
Air bronchograms within the pulmonary parenchyma

Correct answer: Loss of diaphragmatic outline with abdominal organs in the thorax

Loss of the normal diaphragmatic outline combined with abdominal viscera (e.g., intestinal loops, stomach) visible in the thoracic cavity is the hallmark of diaphragmatic hernia.

Question 72: Cytology of a fine-needle aspirate from a splenic mass in a 9-year-old Golden Retriever shows large cells with abundant cytoplasm containing hemosiderin, erythrophagocytosis, and rare mitotic figures with no distinct cell clusters. The most appropriate interpretation is:

Hemangiosarcoma — poorly exfoliating, cytology likely non-diagnostic
Histiocytic sarcoma — aggressive malignancy requiring staging (Correct answer)
Round cell tumor consistent with lymphoma
Extramedullary hematopoiesis — benign, no treatment needed

Correct answer: Histiocytic sarcoma — aggressive malignancy requiring staging

Large pleomorphic cells with erythrophagocytosis and abundant cytoplasm on splenic aspirates are characteristic of histiocytic sarcoma, an aggressive malignancy particularly prevalent in Golden Retrievers and Bernese Mountain Dogs. Hemangiosarcoma is notoriously poorly exfoliating on FNA (blood only usually). Lymphoma shows small-to-large lymphocytes. Extramedullary hematopoiesis lacks pleomorphic large macrophagic cells.

Question 73: A 6-year-old spayed female Doberman Pinscher presents with a 2-week history of anorexia, weight loss, and ascites. Physical exam reveals icterus and hepatomegaly. Bloodwork: ALT 850 U/L, ALP 340 U/L, total bilirubin 6.2 mg/dL, albumin 1.8 g/dL, glucose 58 mg/dL. Coagulation panel: PT prolonged, PTT prolonged, fibrinogen low, D-dimer elevated. Abdominal ultrasound shows a nodular liver with portal hypertension. Liver cytology via ultrasound-guided FNA shows hepatocytes with intracytoplasmic copper granules. Which statement about copper-associated hepatopathy in Dobermans is MOST accurate?

Genetic copper storage disease in Dobermans is linked to mutations in ATP7A rather than ATP7B
Dobermans carry a distinct mutation in COMMD1, the same gene implicated in Bedlington Terriers
Copper accumulation in Dobermans is always secondary to cholestasis, not a primary metabolic defect
Hepatic copper concentrations in affected Dobermans are typically highest in periportal zones (zone 1), unlike Bedlingtons where zone 3 is predominant (Correct answer)

Correct answer: Hepatic copper concentrations in affected Dobermans are typically highest in periportal zones (zone 1), unlike Bedlingtons where zone 3 is predominant

Copper-associated hepatopathy in Doberman Pinschers demonstrates a periportal (zone 1) distribution of copper accumulation on rhodanine or rubeanic acid staining, which is a key histologic distinguishing feature from Bedlington Terrier copper toxicosis (where copper accumulates in centrilobular/zone 3 hepatocytes). Bedlington Terriers carry COMMD1 mutations; Dobermans have a separate, incompletely characterized genetic basis. The primary vs. secondary distinction remains debated in Dobermans, but their pattern of copper distribution is diagnostically and mechanistically distinct from Bedlingtons.

Question 74: A 6-month-old Labrador Retriever puppy presents for evaluation of exercise intolerance and a loud continuous 'machinery' murmur heard best at the left heart base. What is the most likely congenital defect?

Ventricular septal defect
Patent ductus arteriosus (Correct answer)
Pulmonic stenosis
Aortic stenosis

Correct answer: Patent ductus arteriosus

Patent ductus arteriosus produces the classic continuous 'machinery' murmur due to left-to-right shunting throughout the cardiac cycle via the unclosed ductus.

Question 75: A cat develops bradycardia and hypotension following topical application of an ophthalmic timolol solution. What is the mechanism of this adverse effect?

Direct myocardial toxicity of the benzalkonium chloride preservative
Activation of the oculocardiac reflex by the drops
Alpha-1 agonist activity at cardiac receptors
Systemic absorption of the beta-blocker through the nasolacrimal duct (Correct answer)

Correct answer: Systemic absorption of the beta-blocker through the nasolacrimal duct

Timolol is absorbed systemically via the nasolacrimal duct in cats, exerting beta-1 blockade effects on heart rate and blood pressure.

Question 76: A bearded dragon is presented with a black beard, lethargy, and yellow-white caseous plugs in the intestine on necropsy. The causative agent is:

Salmonella enterica
Cryptosporidium varanii
Entamoeba invadens (Correct answer)
Histomonas meleagridis

Correct answer: Entamoeba invadens

Entamoeba invadens causes severe ulcerative enterocolitis in reptiles, particularly lizards, presenting with caseous intestinal lesions and rapid death.

Question 77: A 1,200-head Holstein dairy uses a voluntary waiting period (VWP) of 50 days. Herd records show mean days to first service = 58 days, mean days open = 145 days, and 12-month rolling culling rate = 32%. The herd veterinarian proposes shortening the VWP to 35 days. Which of the following accurately predicts the PRIMARY unintended consequence of this change in a high-producing herd averaging 95 lbs/cow/day at peak?

Mastitis incidence will increase due to immunosuppression associated with early resumption of luteal activity
Culling rate will increase because shortened inter-calving intervals reduce productive life
Milk yield in the subsequent lactation will decrease because early rebreeding reduces the length of the current lactation
First-service conception rate will decline because insemination will more frequently occur before complete uterine involution and during peak negative energy balance (Correct answer)

Correct answer: First-service conception rate will decline because insemination will more frequently occur before complete uterine involution and during peak negative energy balance

In high-producing dairy cows, the nadir of negative energy balance (NEB) typically occurs between 10–14 days in milk, but NEB persists and substantially impairs reproductive function through ~50–60 DIM. Shortening the VWP to 35 days means many cows will be inseminated while still in NEB, with incomplete uterine involution, suboptimal progesterone profiles, and impaired embryo survival. Research consistently shows that conception rates at early first service in high-producers are 8–15 percentage points lower than services at 50–60 DIM. Additionally, uterine involution is not complete in many cows before 40–45 DIM. The net result is more services per conception and no improvement in days open, negating the intended benefit.

Question 78: A producer wants to implement a PRRSV (Porcine Reproductive and Respiratory Syndrome Virus) control program. Wait—this is a bovine herd. Which respiratory virus causes 'shipping fever' complex and is commonly controlled with modified-live virus vaccines in beef cattle?

Bovine respiratory syncytial virus (BRSV)
Parainfluenza-3 virus (PI3)
Bovine coronavirus (BCoV)
Infectious bovine rhinotracheitis virus (IBRV/BHV-1) (Correct answer)

Correct answer: Infectious bovine rhinotracheitis virus (IBRV/BHV-1)

IBRV (BHV-1) is a primary viral pathogen in the bovine respiratory disease complex, and modified-live IBR vaccines are a cornerstone of BRD prevention programs in beef cattle.

Question 79: A veterinarian prescribes phenobarbital to a 4-year-old epileptic dog. After 6 months of stable seizure control, breakthrough seizures occur despite unchanged dosing. Serum phenobarbital levels are now below therapeutic range. No drug interactions or compliance issues are identified. What pharmacokinetic phenomenon best explains this finding?

Renal tubular secretion of phenobarbital increases with chronic exposure
Enterohepatic recirculation of phenobarbital decreases progressively with hepatic adaptation
Phenobarbital induces its own hepatic metabolism (autoinduction) via CYP enzyme upregulation (Correct answer)
Phenobarbital undergoes tachyphylaxis at GABA-A receptors over time

Correct answer: Phenobarbital induces its own hepatic metabolism (autoinduction) via CYP enzyme upregulation

Phenobarbital is a classic example of autoinduction — it induces the hepatic cytochrome P450 enzymes (particularly CYP2B and CYP3A) responsible for its own metabolism. With chronic administration, enzyme induction progressively accelerates phenobarbital clearance, causing serum levels to fall below therapeutic range even at a fixed dose. This typically occurs within weeks to months and necessitates dose escalation. Therapeutic drug monitoring is essential; target serum levels in dogs are 20–40 µg/mL.

Question 80: How would you handle FIP with ocular involvement?

Glycopyrrolate
Topical pilocarpine
Topical steroids and atropine (Correct answer)
Topical antibiotics (2'bacterial infections)

Correct answer: Topical steroids and atropine

Ocular involvement in FIP often manifests as uveitis, causing inflammation, pain, and vision impairment. Topical steroids (e.g., prednisolone acetate) are used to reduce inflammation, while topical atropine is used to relieve ciliary spasm, dilate the pupil, and prevent synechia formation. This combination effectively manages the pain and complications associated with FIP-related uveitis.

Question 81: A veterinarian is establishing a herd health program for a 500-cow dairy. Which parameter best defines 'failure of passive transfer' (FPT) in dairy calves?

Serum IgG <10 g/L measured at 1-2 weeks of age
Total serum protein <5.0 g/dL measured at 24-48 hours of age
Serum IgG <5 g/L measured within 6 hours of birth
Serum IgG <10 g/L measured at 24-48 hours of age (Correct answer)

Correct answer: Serum IgG <10 g/L measured at 24-48 hours of age

FPT is defined as serum IgG <10 g/L (or serum total protein <5.2 g/dL as a surrogate) measured at 24-48 hours of age, after the gut closes to macromolecular absorption.

Question 82: A 4-year-old African grey parrot presents with progressive ataxia, regurgitation, and a dilated proventriculus on radiograph. Crop biopsy reveals lymphoplasmacytic infiltration of the myenteric ganglia. Which of the following is the MOST accurate statement regarding the etiologic agent?

It is a double-stranded DNA virus in the family Herpesviridae that induces T-cell lymphoma in the myenteric plexus
It is a negative-sense, segmented RNA virus in the family Orthomyxoviridae that causes secondary demyelination of enteric nerves
It is a positive-sense, single-stranded RNA virus in the family Coronaviridae that primarily damages proventricular smooth muscle
It is a negative-sense, single-stranded RNA virus in the family Bornaviridae that targets glial cells and neurons of the enteric and central nervous systems (Correct answer)

Correct answer: It is a negative-sense, single-stranded RNA virus in the family Bornaviridae that targets glial cells and neurons of the enteric and central nervous systems

Proventricular Dilatation Disease (PDD) is caused by Avian Bornavirus (ABV), a non-segmented, negative-sense, single-stranded RNA virus in the family Bornaviridae. It targets neurons and glial cells of both the enteric (myenteric plexus) and central nervous systems, producing lymphoplasmacytic ganglioneuritis. The other options describe incorrect viral families or pathomechanisms.

Question 83: Calf scours causing the highest mortality in calves under 5 days of age on a US beef operation is most commonly caused by which pathogen?

Salmonella typhimurium
Rotavirus
Escherichia coli (enterotoxigenic) (Correct answer)
Cryptosporidium parvum

Correct answer: Escherichia coli (enterotoxigenic)

Enterotoxigenic E. coli (K99 fimbriae, F5 antigen) causes profuse watery diarrhea and rapid death in calves under 4 days old due to severe dehydration.

Question 84: NSAIDs reduce pain and inflammation primarily by inhibiting which enzyme, thereby reducing prostaglandin synthesis?

Cyclooxygenase (COX) (Correct answer)
Phospholipase A2
Histidine decarboxylase
Lipoxygenase (LOX)

Correct answer: Cyclooxygenase (COX)

NSAIDs inhibit cyclooxygenase enzymes (COX-1 and/or COX-2), which are required to convert arachidonic acid into prostaglandins and thromboxanes, thereby reducing pain, inflammation, and fever.

Question 85: Which class of drugs can cause crystalluria and urinary obstruction in dogs, particularly in acidic urine?

Fluoroquinolones
Aminoglycosides
Tetracyclines
Sulfonamides (Correct answer)

Correct answer: Sulfonamides

Sulfonamides can precipitate in acidic urine and form crystals, potentially causing crystalluria, hematuria, and renal tubular obstruction.

Question 86: A radiograph of a cat's elbow shows periarticular soft tissue swelling and subchondral bone lysis without significant new bone production. This pattern is most consistent with:

Osteochondrosis dissecans
Degenerative joint disease
Hypertrophic osteodystrophy
Septic arthritis (Correct answer)

Correct answer: Septic arthritis

Septic arthritis characteristically causes joint space narrowing, subchondral bone lysis, and periarticular soft tissue swelling with minimal productive bone response.

Question 87: Which internal parasite of cattle causes 'bottle jaw' (submandibular edema) due to hypoproteinemia?

Ostertagia ostertagi
Trichostrongylus axei
Haemonchus placei (Correct answer)
Cooperia oncophora

Correct answer: Haemonchus placei

Haemonchus placei is a blood-sucking abomasal parasite that causes significant protein loss, leading to hypoproteinemia and the classic sign of submandibular edema (bottle jaw).

Question 88: Both FIP types are fatal and progressive.

False
True (Correct answer)

Correct answer: True

Both the 'wet' (effusive) and 'dry' (non-effusive) forms of Feline Infectious Peritonitis (FIP) are progressive and, if left untreated, are almost invariably fatal. The disease causes widespread inflammation and organ damage, leading to a rapid decline in health, making the statement true.

Question 89: When performing a high plantar nerve block (high 2-point block) in the horse, the targeted nerves are located:

Just proximal to the fetlock, medial and lateral to the flexor tendons
At the level of the tarsus, caudal to the saphenous vein
Midway up the cannon bone, abaxial to the suspensory ligament (Correct answer)
At the level of the proximal sesamoid bones

Correct answer: Midway up the cannon bone, abaxial to the suspensory ligament

The high plantar (high 2-point) block is performed midway up the cannon bone, anesthetizing the medial and lateral plantar nerves abaxial to the suspensory ligament.

Question 90: A 1,200-head commercial feedlot is experiencing an increased rate of liver condemnations at slaughter (18% vs. the target <10%). Rumen pH monitoring via rumenocentesis on 12 randomly selected cattle 6 hours post-feeding shows a mean rumen pH of 5.8 with 4 animals below 5.5. The current ration uses dry-rolled corn at 85% of dry matter. Which management change will MOST directly address the primary pathophysiological mechanism driving the liver condemnation rate?

Increase dietary roughage inclusion from 5% to 12% to buffer rumen pH
Add virginiamycin at 17 g/ton to suppress lactic acid-producing Streptococcus bovis
Add monensin at 200–360 mg/head/day to shift ruminal fermentation toward propionate (Correct answer)
Switch from dry-rolled to high-moisture corn to slow starch fermentation rate

Correct answer: Add monensin at 200–360 mg/head/day to shift ruminal fermentation toward propionate

Liver abscesses (the primary cause of liver condemnations in feedlots) result from rumenitis → rumen wall ulceration → bacteremia with Fusobacterium necrophorum seeding the liver. Subacute rumen acidosis (SARA, pH 5.5–5.8) is the driver of rumenitis. Monensin, an ionophore, shifts fermentation away from butyrate/propionate ratios that damage the rumen epithelium, reduces lactic acid accumulation, and directly reduces liver abscess rates by ~50% — the most validated single intervention. High-moisture corn actually ferments more rapidly than dry-rolled corn, potentially worsening acidosis. Increasing roughage helps buffer pH but is less targeted and reduces energy density. Virginiamycin specifically targets acute lactic acidosis (Streptococcus bovis/Lactobacillus), which is not the predominant concern here given pH values in the SARA range rather than <5.0.

Question 91: A cat is found to have hypokalemia (K+ 2.8 mEq/L) and symmetric cervical ventroflexion. Which underlying disease is most commonly associated with this presentation in cats?

Pheochromocytoma
Hyperaldosteronism (Conn's syndrome) (Correct answer)
Hypothyroidism
Addison's disease

Correct answer: Hyperaldosteronism (Conn's syndrome)

Primary hyperaldosteronism (Conn's syndrome) causes chronic hypokalemia in cats, leading to hypokalemic polymyopathy characterized by ventroflexion of the neck.

Question 92: A goat kid presents at 2 days of age with failure to nurse, profuse watery diarrhea, and rapid dehydration. Feces are negative for Cryptosporidium and E. coli. Rotavirus ELISA is positive. Treatment priorities include:

Sulfonamide antibiotics and probiotics
Corticosteroids to reduce intestinal inflammation
Anthelmintic deworming
Oral electrolyte fluid therapy and supportive care (Correct answer)

Correct answer: Oral electrolyte fluid therapy and supportive care

Rotavirus diarrhea in neonatal ruminants is managed supportively with oral electrolyte replacement because the disease is viral and antibiotics are ineffective; correction of dehydration is paramount.

Question 93: In nuclear scintigraphy, a 'cold spot' on a thyroid scan in a dog MOST likely represents:

Normal thyroid tissue
Hyperfunctional adenoma
Nonfunctional or necrotic tissue within the thyroid (Correct answer)
Ectopic thyroid tissue

Correct answer: Nonfunctional or necrotic tissue within the thyroid

A cold (photopenic) area on thyroid scintigraphy indicates reduced radionuclide uptake, consistent with nonfunctional, necrotic, or cystic tissue.

Question 94: A cat is diagnosed with feline infectious peritonitis (FIP). Which antiviral drug has shown efficacy and received conditional FDA approval for this disease?

GS-441524 (Correct answer)
Oseltamivir
Interferon omega
Famciclovir

Correct answer: GS-441524

GS-441524, an adenosine nucleoside analog, inhibits feline coronavirus RNA-dependent RNA polymerase and has conditional FDA approval as Mutian/brand equivalents for FIP.

Question 95: A community outbreak of E. coli O157:H7 is traced to a petting zoo. The primary mode of transmission in this setting is:

Fecal-oral transmission through direct animal contact (Correct answer)
Vectorborne transmission via insects in the zoo
Airborne transmission from animal dander
Waterborne transmission from decorative ponds

Correct answer: Fecal-oral transmission through direct animal contact

E. coli O157:H7 is shed in the feces of ruminants and transmitted to humans via fecal-oral contact in petting zoo settings.

Question 96: A rancher reports abortions in 8% of his beef cows in the last trimester. Brucella abortus is confirmed. Which test is used for the official US brucellosis eradication program to test individual cattle?

Complement fixation test
PCR of milk
Card test (Rose Bengal plate test) (Correct answer)
ELISA only

Correct answer: Card test (Rose Bengal plate test)

The card (Rose Bengal) test is the approved screening test in the US brucellosis eradication program, with positive reactors confirmed by the buffered acidified plate antigen (BAPA) or fluorescent polarization assay.

Question 97: A 2-year-old Thoroughbred colt has bilateral forelimb angular limb deformity (valgus) at the carpus identified at 4 months of age. Radiographs show the deformity originates at the distal radial physis. The foal is now presenting at 6 months without improvement. What surgical option should be considered?

Periosteal stripping on the concave side of the deformity
Medial condylar resection of the distal radius
Arthrodesis of the radiocarpal joint
Transphyseal bridging (screw and wire or staple) on the convex side (Correct answer)

Correct answer: Transphyseal bridging (screw and wire or staple) on the convex side

Transphyseal bridging on the convex (lateral) side of a carpal valgus deformity slows growth on that side, allowing the concave side to 'catch up' and correct the angular deformity.

Question 98: A veterinarian is performing a herd reproductive evaluation. Which metric best represents overall reproductive efficiency in a beef cow-calf operation?

Pregnancy rate per estrous cycle (PR/EC)
Conception rate to first service
Percentage of cows pregnant by 90 days post-calving (21-day pregnancy rate) (Correct answer)
Bull-to-cow ratio during the breeding season

Correct answer: Percentage of cows pregnant by 90 days post-calving (21-day pregnancy rate)

The percentage of cows pregnant by 90 days post-calving (equivalent to a 90-day breeding season) measures overall reproductive efficiency by accounting for both conception rate and submission rate.

Question 99: A 7-year-old Doberman Pinscher presents with exercise intolerance, ascites, and a gallop rhythm. Echocardiography shows a dilated left ventricle with reduced fractional shortening of 12%. What is the most likely diagnosis?

Dilated cardiomyopathy (Correct answer)
Mitral valve endocardiosis
Hypertrophic cardiomyopathy
Pericardial effusion

Correct answer: Dilated cardiomyopathy

Dilated cardiomyopathy with reduced fractional shortening and a dilated left ventricle is the classic presentation in Dobermans.

Question 100: On thoracic radiographs of a 7-year-old male Golden Retriever, you observe a soft tissue opacity mass at the right cardiac apex that obscures the cardiac silhouette border. Which radiographic sign is this, and what does it indicate?

Summation artifact; overlapping lung lobes are mimicking a true mass lesion
Silhouette sign; the mass is in contact with and of similar opacity to the cardiac border, indicating it is within the same radiographic plane (Correct answer)
Border effacement; the mass is displacing the heart cranially and is of pulmonary origin
Mediastinal shift sign; the mass is causing contralateral displacement of the trachea

Correct answer: Silhouette sign; the mass is in contact with and of similar opacity to the cardiac border, indicating it is within the same radiographic plane

The silhouette sign (Roentgen sign) occurs when two structures of the same radiographic opacity are in contact — their shared border becomes invisible. Here, a soft tissue mass contiguous with the cardiac silhouette will obliterate that border, indicating the mass is in the same radiographic plane as the heart (e.g., right middle lung lobe, pericardial, or cardiac in origin). This is a critical interpretive principle for localizing intrathoracic lesions.

Question 101: A Labrador retriever aged 7 is examined for developing foreleg lameness that has been present for about two months. Physical examination reveals a noticeable soft tissue bulge around the carpus, and palpating this region causes severe pain. Radiographs of the afflicted area show significant cortical bone loss and lysis of the distal radius. Osteoblasts with many mitotic patterns, peculiar nuclei, and very basophilic cytoplasm are visible in a needle biopsy. What type of medication is the most suitable if the owner decides to have an amputation?

Cisplatin (Correct answer)
Azathioprine
Prednisone
Vincristine

Correct answer: Cisplatin

The clinical signs and biopsy results (cortical bone loss, lysis, atypical osteoblasts) are highly suggestive of osteosarcoma, an aggressive bone tumor. For appendicular osteosarcoma, amputation is often followed by chemotherapy to delay metastasis and improve survival. Cisplatin is a commonly used and effective chemotherapeutic agent for canine osteosarcoma, making it the most suitable medication post-amputation.

Question 102: An 8-year-old Dachshund presents with acute onset of severe back pain and inability to ambulate. MRI confirms acute thoracolumbar IVDD at T12-13. Deep pain perception is absent. Within what time frame should surgical decompression ideally occur to maximize neurological recovery?

Within 6 hours
Within 4 hours
Within 24 hours
Within 48 hours (Correct answer)

Correct answer: Within 48 hours

Surgical decompression within 48 hours of loss of deep pain perception is associated with the best neurological outcomes in acute IVDD.

Question 103: An 800-cow beef cow-calf operation has experienced a 14% calf loss from birth to weaning over the past two years. Post-mortem findings in calves under 3 days old predominantly show fibrinous peritonitis and omphalophlebitis. In calves 3–21 days old, findings are predominantly abomasal bloat and villous atrophy. Which integrated management change addresses BOTH age-specific mortality peaks simultaneously?

Increase colostrum feeding volume to 4 liters within 2 hours of birth and supplement with oral zinc
Vaccinate calves at birth with a modified-live BRD vaccine and treat all navels with 7% tincture of iodine
Implement a Sandhills Calving System and vaccinate cows pre-partum with a multivalent scours vaccine containing K99 E. coli, rotavirus, coronavirus, and Clostridium perfringens C&D (Correct answer)
Administer prophylactic oral electrolytes to all newborn calves and move to a barn calving system with individual pens

Correct answer: Implement a Sandhills Calving System and vaccinate cows pre-partum with a multivalent scours vaccine containing K99 E. coli, rotavirus, coronavirus, and Clostridium perfringens C&D

The neonatal deaths (<3 days) with omphalophlebitis and peritonitis suggest failure of passive transfer combined with environmental contamination (navel infection), consistent with high pathogen load in the calving area. Deaths at 3–21 days with villous atrophy point to enteric viral pathogens (rotavirus/coronavirus). The Sandhills Calving System (moving cow-calf pairs away from the calving area as calves age) dramatically reduces pathogen build-up, addressing early-neonatal infection risk. Pre-partum cow vaccination with a multivalent scours vaccine boosts colostral antibodies against the enteric pathogens responsible for the later peak. The combination targets both windows of loss synergistically.

Question 104: A 9-year-old dog is presented for chronic, unilateral nasal discharge. To evaluate the extent of disease, including potential bone destruction of the nasal turbinates and integrity of the cribriform plate, which advanced imaging modality is superior?

Computed Tomography (CT) (Correct answer)
Dental radiography
Magnetic Resonance Imaging (MRI)
Rhinoscopy with biopsy

Correct answer: Computed Tomography (CT)

Computed Tomography (CT) is the imaging modality of choice for evaluating the nasal passages because of its excellent spatial resolution and superior ability to detail bone. It eliminates the superimposition of structures seen on radiographs and is better than MRI for assessing fine bony changes like turbinate destruction or lysis of the cribriform plate, which is critical for staging nasal tumors or fungal disease. While rhinoscopy is needed for biopsy, CT provides the best anatomical map for surgical or radiation planning.

Question 105: A positive response to a distal limb flexion test in a horse is most useful for localizing pain to which general anatomical area?

Stifle and tarsus
Metacarpophalangeal joint and structures distal to it (Correct answer)
Carpus and proximal metacarpal region
Elbow and shoulder

Correct answer: Metacarpophalangeal joint and structures distal to it

The distal limb flexion test specifically applies pressure to the joints and associated soft tissues of the fetlock, pastern, and coffin joint. A positive response (an increase in lameness after the hold) suggests a pain source within this region. While not perfectly specific, it effectively rules out primary pain from more proximal structures like the carpus, stifle, or shoulder, which are not significantly stressed by this particular test.

Question 106: A dog receives acepromazine premedication followed by isoflurane anesthesia. It develops refractory hypotension unresponsive to fluids. Which vasopressor is most appropriate?

Norepinephrine CRI
Phenylephrine bolus
Ephedrine IV bolus (Correct answer)
Dopamine at 2 mcg/kg/min

Correct answer: Ephedrine IV bolus

Ephedrine has both alpha and beta agonist activity and is effective for treating hypotension caused by vasodilation from acepromazine plus inhalant anesthesia.

Question 107: An equine practitioner is treating a horse with endotoxemia and considers using polymyxin B for lipopolysaccharide neutralization. The horse also has acute kidney injury (creatinine 4.8 mg/dL). Which statement most accurately reflects the pharmacological risk in this scenario?

Polymyxin B is primarily hepatically metabolized; renal dysfunction does not affect its safety profile
Polymyxin B nephrotoxicity is mediated exclusively through prostaglandin inhibition and is reversible with NSAIDs
Renal impairment increases polymyxin B protein binding, paradoxically reducing free drug toxicity
Polymyxin B causes nephrotoxicity via tubular cell membrane disruption and accumulates with renal impairment, compounding existing injury (Correct answer)

Correct answer: Polymyxin B causes nephrotoxicity via tubular cell membrane disruption and accumulates with renal impairment, compounding existing injury

Polymyxin B is nephrotoxic due to its cationic detergent-like mechanism, which disrupts renal proximal tubular cell membranes. The drug undergoes renal elimination, and in horses with pre-existing acute kidney injury, reduced GFR leads to drug accumulation, markedly amplifying tubular toxicity. Use in patients with renal dysfunction is controversial; if used, very low doses (1,000–2,000 IU/kg IV) with aggressive fluid support and close renal monitoring are essential. The LPS-neutralizing benefit must be carefully weighed against the risk of worsening renal failure.

Question 108: When calculating the economic impact of mastitis in a dairy herd, which production loss component is typically the largest?

Reduced milk production (discarded milk + production drop) (Correct answer)
Premature culling costs
Antibiotic treatment costs
Veterinary labor and diagnostic fees

Correct answer: Reduced milk production (discarded milk + production drop)

Reduced milk yield accounts for approximately 60–70% of total mastitis costs; clinical and subclinical cases each cow produces significantly less milk throughout the lactation.

Question 109: Which epidemiological measure best quantifies the additional risk of disease attributable to a specific exposure?

Odds ratio
Relative risk
Attributable risk (risk difference) (Correct answer)
Incidence rate

Correct answer: Attributable risk (risk difference)

Attributable risk (risk difference) measures the excess disease burden among the exposed group that is directly attributable to the exposure.

Question 110: A 5-year-old Holstein cow has not shown estrus 60 days postpartum. Rectal palpation reveals a corpus luteum (CL) on one ovary with no other abnormalities. Which treatment protocol is most appropriate to initiate cyclicity?

Administer GnRH to stimulate follicle-stimulating hormone release
Begin a progesterone-releasing intravaginal device (PRID) for 14 days
Administer prostaglandin F2α (PGF2α) to lyse the CL and allow return to estrus (Correct answer)
Administer estradiol cypionate to induce a standing heat

Correct answer: Administer prostaglandin F2α (PGF2α) to lyse the CL and allow return to estrus

A persistent CL causing anestrus is treated with prostaglandin F2α (dinoprost or cloprostenol), which causes luteolysis — regression of the CL, progesterone levels drop, and the cow returns to estrus within 2–5 days. GnRH induces ovulation of the dominant follicle but does not address a persistent CL. PRIDs are used for synchronization, not CL regression.

Question 111: A warmblood dressage horse presents with bilateral hindlimb toe-dragging and a shuffling gait. Neurological examination reveals hindlimb ataxia. The MOST important differential diagnosis to rule out first is:

Bilateral upward fixation of the patella
Bilateral bone spavin
Bilateral proximal suspensory desmitis
Cervical vertebral stenotic myelopathy (Wobbler syndrome) (Correct answer)

Correct answer: Cervical vertebral stenotic myelopathy (Wobbler syndrome)

Cervical vertebral stenotic myelopathy (Wobbler syndrome) causes compressive spinal cord disease manifesting as hindlimb ataxia and toe-dragging and must be differentiated from primary joint lameness.

Question 112: Which of the following common canine uroliths is most likely to be radiolucent on survey abdominal radiographs, often requiring contrast cystography or ultrasonography for diagnosis?

Ammonium Urate (Correct answer)
Silica
Calcium Oxalate Monohydrate
Struvite (Magnesium Ammonium Phosphate)

Correct answer: Ammonium Urate

Ammonium urate and cystine uroliths are typically radiolucent or only faintly radiopaque, making them difficult to see on standard radiographs. In contrast, struvite and calcium oxalate uroliths are mineral-dense and almost always radiopaque.

Question 113: Which radiographic view is most useful for evaluating the dens (odontoid process) of the axis (C2) in a dog for atlantoaxial instability?

Lateral cervical with flexion
Open-mouth ventrodorsal (Correct answer)
Lateral cervical with extension
Oblique cervical

Correct answer: Open-mouth ventrodorsal

The open-mouth ventrodorsal view projects the dens through the mouth and allows direct visualization of the atlantoaxial articulation and dens morphology.

Question 114: During an arthroscopic surgery of the equine tarsocrural joint, you inadvertently lacerate the medial branch of the deep peroneal nerve. Which immediate postoperative complication is most specifically associated with this iatrogenic injury in the horse?

Inability to extend the digit, resulting in knuckling at the fetlock
Loss of sensation over the dorsal metatarsus with no motor deficit (Correct answer)
Persistent swelling of the dorsomedial tarsocrural joint pouch due to impaired lymphatic drainage
Denervation atrophy of the extensor digitorum longus muscle

Correct answer: Loss of sensation over the dorsal metatarsus with no motor deficit

The medial branch of the deep peroneal (fibular) nerve in the horse is primarily sensory to the dorsal metatarsus and dorsal fetlock region. Damage to this branch produces analgesia/hypoalgesia of the dorsal metatarsus without meaningful motor loss, since the motor contributions to the digital extensors arise from the main trunk more proximally. Knuckling at the fetlock results from damage to the extensor branches of the peroneal nerve much more proximally, or from true extensor muscle denervation — not from the medial branch at the tarsocrural level. Lymphatic effects are not attributable to this nerve.

Question 115: Which statement most accurately describes the use of bisphosphonates (e.g., tiludronate) in equine lameness management?

They are first-line treatment for acute septic arthritis
They stimulate cartilage repair in osteoarthritic joints
They inhibit osteoclast activity and are approved for navicular syndrome and other bone remodeling disorders in horses (Correct answer)
They are contraindicated in horses under 4 years due to growth plate interference

Correct answer: They inhibit osteoclast activity and are approved for navicular syndrome and other bone remodeling disorders in horses

Tiludronate (Tildren) and clodronate (Osphos) are bisphosphonates approved in horses that inhibit osteoclast-mediated bone resorption and are indicated for navicular syndrome and other conditions with pathologic bone remodeling.

Question 116: Which electrolyte abnormality is most commonly associated with hypoadrenocorticism (Addison's disease) in dogs?

Hyponatremia and hyperkalemia (Correct answer)
Hypercalcemia and hyperphosphatemia
Hypomagnesemia and hypochloremia
Hypernatremia and hypokalemia

Correct answer: Hyponatremia and hyperkalemia

Lack of mineralocorticoids in Addison's disease leads to sodium wasting and potassium retention, producing hyponatremia and hyperkalemia with a Na:K ratio below 27.

Question 117: A 7-year-old intact male Cavalier King Charles Spaniel presents with a 3-week history of progressive exercise intolerance and a grade IV/VI left apical systolic murmur. Thoracic radiographs reveal moderate left atrial enlargement with pulmonary venous distension but no overt edema. Per EPIC trial criteria, which treatment is most appropriate at this time?

Spironolactone 2 mg/kg PO SID
Enalapril 0.5 mg/kg PO BID
Furosemide 2 mg/kg PO BID
Pimobendan 0.25–0.3 mg/kg PO BID (Correct answer)

Correct answer: Pimobendan 0.25–0.3 mg/kg PO BID

The EPIC trial demonstrated that pimobendan initiated in the preclinical (Stage B2) phase of myxomatous mitral valve disease — defined by cardiomegaly on radiographs or echocardiography (LVIDDN ≥1.7 or vertebral heart score ≥10.5) — significantly delayed onset of CHF by a median of 15 months. Furosemide is reserved for overt heart failure (Stage C/D). ACE inhibitors and spironolactone are not indicated as monotherapy in B2 per current ACVIM guidelines post-EPIC.

Question 118: In a feedlot, the recommended withdrawal time before slaughter must be observed when using which antibiotic for treatment of bovine respiratory disease?

Tulathromycin (Correct answer)
Vitamin A injection
Flunixin meglumine
Balanced electrolyte solution

Correct answer: Tulathromycin

Tulathromycin (Draxxin) has a meat withdrawal time of 18 days in the US, and compliance is required to ensure drug residue-free beef at slaughter.

Question 119: A 'string of pearls' sign on abdominal radiographs of a cat refers to:

Mineralization of lymph nodes in the mesentery
Small gas bubbles trapped between intestinal folds indicating ileus (Correct answer)
Multiple uroliths in the ureter
Gas within the portal vasculature

Correct answer: Small gas bubbles trapped between intestinal folds indicating ileus

The 'string of pearls' sign describes small gas bubbles trapped between the valvulae conniventes in paralytic ileus, indicating functional obstruction.

Question 120: Among commonly used local anesthetics in veterinary medicine, which agent provides the LONGEST duration of nerve block?

Mepivacaine
Procaine
Lidocaine
Bupivacaine (Correct answer)

Correct answer: Bupivacaine

Bupivacaine has the longest duration of action among common local anesthetics (4–8 hours for nerve blocks) due to its high protein binding and lipid solubility, making it ideal for postoperative pain management.

Question 121: An 8-year-old Arabian mare undergoes ovariectomy via flank laparotomy. On post-op day 2, she develops acute abdominal pain and pyrexia. Abdominocentesis reveals yellow-tinged fluid with a total protein of 4.5 g/dL and WBC of 90,000 cells/μL. What is the most likely complication?

Incisional seroma
Normal post-operative peritoneal response
Peritonitis secondary to intestinal contamination or pedicle infection (Correct answer)
Cecal impaction

Correct answer: Peritonitis secondary to intestinal contamination or pedicle infection

Markedly elevated peritoneal fluid protein and WBC with fever and pain indicate septic peritonitis, a serious complication of flank ovariectomy typically due to contamination or pedicle infection.

Question 122: Grass tetany (hypomagnesemic tetany) in beef cattle grazing lush spring pastures is best prevented by supplementing which mineral?

Zinc sulfate boluses
Sodium bicarbonate free-choice
Calcium carbonate in water
Magnesium oxide in mineral mix (Correct answer)

Correct answer: Magnesium oxide in mineral mix

Grass tetany results from hypomagnesemia; magnesium oxide in a palatable mineral mix is the standard prevention because magnesium has no adequate body reserve.

Question 123: Following a bilateral thyroidectomy, a 11-year-old female domestic shorthair cat is released from the hospital. The patient is reevaluated two days later due to panting, agitation, and a recent seizure. Which postoperative complication is most likely to account for these clinical symptoms?

Hypocalcemia
Hypoparathyroidism (Correct answer)
Renal disease
Horner's syndrome

Correct answer: Hypoparathyroidism

Bilateral thyroidectomy in cats often involves inadvertent removal or damage to the parathyroid glands, which are closely associated with the thyroid. The parathyroid glands regulate calcium levels via PTH. Postoperative hypoparathyroidism leads to hypocalcemia, causing increased neuromuscular excitability that manifests as panting, agitation, and seizures, making it the most likely complication.

Question 124: Which of the following best describes the pharmacokinetic term 'volume of distribution' (Vd)?

A theoretical volume relating plasma drug concentration to total drug in the body (Correct answer)
The fraction of an oral dose reaching systemic circulation
The time for plasma drug concentration to decrease by 50%
The rate at which a drug is eliminated from the body

Correct answer: A theoretical volume relating plasma drug concentration to total drug in the body

Volume of distribution is a theoretical volume that relates the total amount of drug in the body to the concentration measured in plasma.

Question 125: Which Salmonella serotype is most commonly associated with poultry products and represents the leading cause of salmonellosis in the US?

Salmonella Choleraesuis
Salmonella Typhi
Salmonella Enteritidis (Correct answer)
Salmonella Dublin

Correct answer: Salmonella Enteritidis

Salmonella Enteritidis is the most common serotype linked to poultry and eggs and is a major cause of human foodborne illness in the US.

Question 126: In a dog with suspected intervertebral disc disease, which myelographic finding confirms extradural compression?

Complete absence of contrast cranial to the lesion
Pooling of contrast material within the spinal cord
Widening of the subarachnoid space at the lesion site
Thinning or deviation of the contrast column on one or both sides (Correct answer)

Correct answer: Thinning or deviation of the contrast column on one or both sides

Extradural compression from a disc extrusion causes thinning or lateral deviation of the myelographic contrast column at the lesion level.

Question 127: A 7-year-old Great Dane presents with acute, non-productive retching, hypersalivation, and a distended, tympanic abdomen. A right lateral abdominal radiograph is taken. Which radiographic finding is most pathognomonic for gastric dilatation-volvulus (GDV)?

Displacement of the small intestines to the right cranial abdomen.
A soft tissue opacity compartmentalizing the gas-filled stomach, creating a 'double bubble' appearance. (Correct answer)
Severe gaseous distention of the entire stomach with a normal pyloric position.
The presence of gravel or foreign material within the gastric lumen.

Correct answer: A soft tissue opacity compartmentalizing the gas-filled stomach, creating a 'double bubble' appearance.

The classic radiographic sign for GDV on a right lateral view is the compartmentalization of the stomach by a soft tissue band, which is the pylorus folding over the fundus. This creates what is often described as a 'double bubble', 'Smurf hat', or 'Popeye arm' appearance and is pathognomonic for the condition.

Question 128: A horse presents with acute colic, nasogastric reflux >2 L, absent borborygmi on the right side, and tachycardia of 68 bpm. What is the most likely diagnosis?

Simple large colon impaction
Cecal impaction
Duodenitis-proximal jejunitis (Correct answer)
Large colon displacement to the right (right dorsal displacement)

Correct answer: Duodenitis-proximal jejunitis

Large volumes of nasogastric reflux (>2 L) combined with absent right-sided borborygmi, severe tachycardia, and acute pain are classic for duodenitis-proximal jejunitis (anterior enteritis).

Question 129: A backyard chicken flock presents with sudden death, cyanosis of the comb and wattles, and neurological signs. Which disease should be the primary differential?

Infectious bronchitis
Marek's disease
Newcastle disease (velogenic strain) (Correct answer)
Fowl pox

Correct answer: Newcastle disease (velogenic strain)

Velogenic Newcastle disease causes acute high mortality with concurrent respiratory, nervous, and circulatory signs including cyanosis.

Question 130: A 4-year-old domestic shorthair cat presents with a 3-week history of progressive neurological signs including head tremors, cerebellar ataxia, and vertical nystagmus. The owner recently moved from the Ohio River Valley. CSF analysis shows eosinophilic pleocytosis. Serum Cryptococcus antigen is negative. Which organism is the most likely causative agent?

Cuterebra sp. (aberrant larval migration)
Blastomyces dermatitidis (Correct answer)
Toxoplasma gondii
Coccidioides immitis

Correct answer: Blastomyces dermatitidis

Blastomyces dermatitidis is endemic to the Ohio and Mississippi River Valleys and can cause CNS blastomycosis in cats, presenting with granulomatous meningoencephalitis and eosinophilic pleocytosis. The geographic history is a critical clue. While Toxoplasma is common in cats, it typically causes mixed or neutrophilic pleocytosis and is not geographically restricted. Cuterebra larval migration is possible but does not fit as neatly with the endemic area history. Coccidioides is southwestern U.S., not the Ohio Valley.

Question 131: Which local anesthetic has the highest risk of causing methemoglobinemia in cats?

Bupivacaine
Lidocaine
Ropivacaine
Benzocaine (Correct answer)

Correct answer: Benzocaine

Benzocaine, found in some topical sprays, rapidly induces methemoglobinemia in cats due to their limited ability to metabolize certain oxidizing agents.

Question 132: Which of the following best describes the 'stacked' or 'wedge' effect seen radiographically in horses with palmar foot syndrome (navicular syndrome)?

Increased thickness of the digital flexor tendon on lateromedial view
Gas lucency around the navicular bursa
Synovial invaginations (synovial fossae) that appear as lucent 'lollipop' shapes in the navicular bone (Correct answer)
Periosteal proliferation at the palmar cortex of the navicular bone

Correct answer: Synovial invaginations (synovial fossae) that appear as lucent 'lollipop' shapes in the navicular bone

Synovial fossae (invaginations) in the navicular bone appear as round to oval radiolucencies on the flexor surface, often called 'lollipop' lesions, and are associated with navicular disease.

Question 133: A 5-year-old, male neutered Doberman Pinscher presents for evaluation. Echocardiography reveals a dilated left ventricle with decreased fractional shortening. The owner reports episodes of coughing and exercise intolerance. Which of the following long-term oral medications has been shown to delay the onset of clinical signs and extend the life of Dobermans in the occult stage of this disease?

Enalapril
Furosemide
Pimobendan (Correct answer)
Spironolactone

Correct answer: Pimobendan

Pimobendan, an inodilator, has been proven to delay the onset of congestive heart failure and prolong survival in Doberman Pinschers with preclinical (occult) dilated cardiomyopathy (DCM). While furosemide, enalapril, and spironolactone are used to manage congestive heart failure once it develops, pimobendan is the key therapy for the occult stage.

Question 134: A food inspector observes condensation dripping from overhead pipes onto exposed ready-to-eat food contact surfaces. This represents a violation of which food safety principle?

Temperature control for safety
Sanitation and hygienic design (environmental sanitation) (Correct answer)
Supplier verification
Allergen labeling requirements

Correct answer: Sanitation and hygienic design (environmental sanitation)

Condensation dripping onto food contact surfaces represents an environmental sanitation and hygienic facility design failure, a prerequisite program violation.

Question 135: A rabbit undergoing ovariohysterectomy shows bradycardia (HR 120 bpm) under isoflurane. What is the most likely cause and initial treatment?

Vagal stimulation — administer atropine IV
Anesthetic overdose — reduce vaporizer setting (Correct answer)
Hyperthermia — apply cooling
Hyperkalemia — administer calcium gluconate

Correct answer: Anesthetic overdose — reduce vaporizer setting

Reducing the isoflurane vaporizer setting addresses anesthetic-induced bradycardia by decreasing myocardial depression from excessive anesthetic depth.

Question 136: On abdominal radiographs, a 'string of pearls' gas pattern within the bowel wall is most suggestive of which condition?

Foreign body obstruction
Pneumatosis intestinalis (Correct answer)
Ileus
Intussusception

Correct answer: Pneumatosis intestinalis

Pneumatosis intestinalis (gas within the intestinal wall) produces a 'string of pearls' or bubbly gas pattern and is associated with intestinal necrosis or ischemia.

Question 137: A 12-year-old Quarter Horse cutting horse presents with chronic bilateral hindlimb stiffness and a 'rope-walking' gait. On rectal palpation, crepitus is noted over the lumbosacral region. Standing radiographs are non-diagnostic. Scintigraphy reveals focal increased radiopharmaceutical uptake at L5-S1. Nuclear scintigraphy-guided infiltration of the lumbosacral space with corticosteroid provides marked temporary improvement. What is the most appropriate long-term management strategy if conservative therapy fails after two injection cycles?

Sacroiliac joint arthrodesis via percutaneous implant placement
Extracorporeal shock wave therapy (ESWT) targeted to the lumbosacral facet joints under ultrasound guidance (Correct answer)
Computed tomography-guided chemical neurolysis of the dorsal sacral nerve roots
Retirement from cutting, with consideration of mesotherapy along the thoracolumbar epaxial musculature

Correct answer: Extracorporeal shock wave therapy (ESWT) targeted to the lumbosacral facet joints under ultrasound guidance

For horses with confirmed lumbosacral pathology refractory to intra-articular corticosteroid, extracorporeal shock wave therapy (ESWT) targeted under ultrasound guidance to the lumbosacral facet articulations is a validated next-line intervention. ESWT delivers acoustic energy that modulates pain via nerve fiber hyperpolarization and stimulates local tissue remodeling. It is minimally invasive, can be repeated, and has demonstrated efficacy in peer-reviewed studies for horses with thoracolumbar and lumbosacral pain. Sacroiliac arthrodesis addresses the SI joint but not lumbosacral facets, and chemical neurolysis is not an accepted equine technique for this indication.

Question 138: In avian medicine, which drug is contraindicated in pigeons and doves due to severe toxicity?

Doxycycline
Metronidazole
Enrofloxacin
Fenbendazole at high doses (Correct answer)

Correct answer: Fenbendazole at high doses

Fenbendazole at high doses or prolonged use causes fatal bone marrow suppression in pigeons and doves; caution with dosing is essential.

Question 139: A 4-year-old ferret presents with muscle wasting, hindlimb weakness, and hypoglycemia (blood glucose 40 mg/dL) that resolves with dextrose. The most likely diagnosis is:

Lymphoma
Adrenal gland disease
Aleutian disease
Insulinoma (Correct answer)

Correct answer: Insulinoma

Insulinoma is the most common pancreatic tumor in ferrets over 3 years old and classically causes fasting hypoglycemia, weakness, and neurological signs relieved by glucose administration.

Question 140: A 6-year-old Labrador is undergoing a splenectomy under isoflurane anesthesia. The end-tidal CO2 rises to 65 mmHg. What is the most appropriate initial intervention?

Administer sodium bicarbonate IV
Increase respiratory rate on the ventilator (Correct answer)
Switch to sevoflurane
Increase fresh gas flow rate

Correct answer: Increase respiratory rate on the ventilator

Increasing the ventilator rate will increase minute ventilation and eliminate the excess CO2, correcting the hypercapnia.

Question 141: A shelter veterinarian is investigating a cluster of cats with a highly virulent calicivirus (VS-FCV) outbreak. Affected cats exhibit facial and limb edema, ulceration of the nasal planum, pinnae necrosis, jaundice, and a mortality rate approaching 60%. Which of the following distinguishes VS-FCV from classical FCV strains and has the MOST direct implication for infection control?

VS-FCV is antigenically identical to classical FCV strains, so current vaccines provide complete cross-protective immunity and vaccination immediately halts outbreak spread.
VS-FCV only affects immunocompromised cats; fully vaccinated immunocompetent adults are not susceptible regardless of exposure dose.
VS-FCV is exclusively transmitted via aerosolized droplets and does not persist on fomites, making hand hygiene the sole critical control measure.
VS-FCV is significantly more resistant to commonly used disinfectants, including quaternary ammonium compounds, and requires 1:32 dilution household bleach with extended contact time; it also causes high mortality in vaccinated adult cats. (Correct answer)

Correct answer: VS-FCV is significantly more resistant to commonly used disinfectants, including quaternary ammonium compounds, and requires 1:32 dilution household bleach with extended contact time; it also causes high mortality in vaccinated adult cats.

VS-FCV (virulent systemic FCV) is notable for causing severe systemic disease and death even in vaccinated adult cats, highlighting the limitations of current vaccines against divergent strains. Like classical FCV, it is non-enveloped and highly environmentally stable, resistant to many disinfectants; dilute bleach (1:32) with adequate contact time remains effective. Fomite transmission is a critical route, making environmental decontamination and isolation essential. Vaccines do not provide sterilizing immunity against VS-FCV. Immunocompetent vaccinated adults can and do die.

Question 142: During a routine laparotomy in a 3-year-old male French Bulldog for suspected intestinal foreign body, you discover a 4 cm segment of jejunum that is dark purple, non-peristaltic, and fails to pink up after 10 minutes of warm saline lavage and vascular assessment. The mesenteric vasculature appears intact. You resect the segment. Intraoperatively, what is the MOST critical technical consideration unique to intestinal anastomosis in brachycephalic dogs compared to mesocephalic breeds?

Stapled anastomosis is contraindicated in French Bulldogs due to documented staple-line failure related to breed-specific tissue fragility
The mesenteric border must be closed with interrupted sutures rather than continuous pattern to prevent ischemia in short mesenteries
End-to-end anastomosis carries higher dehiscence risk in brachycephalic dogs secondary to hypoxemia-related impaired wound healing (Correct answer)
Brachycephalic dogs require a larger luminal diameter anastomosis due to higher intraluminal pressures from aerophagia

Correct answer: End-to-end anastomosis carries higher dehiscence risk in brachycephalic dogs secondary to hypoxemia-related impaired wound healing

Brachycephalic dogs are predisposed to chronic intermittent hypoxemia due to upper airway obstruction (stenotic nares, elongated soft palate, hypoplastic trachea). Tissue hypoxia impairs collagen synthesis and wound healing, increasing the risk of anastomotic dehiscence. This is a recognized anesthetic and surgical risk factor specific to the breed conformation. While aerophagia does occur in brachycephalic dogs, it does not necessitate a larger anastomosis diameter. The mesenteric border closure and staple contraindication claims are not evidence-based breed-specific recommendations. Recognition of this hypoxemia-wound healing axis is essential for perioperative planning in these patients.

Question 143: A 10-year-old Quarter Horse with chronic, bilateral forelimb lameness undergoes a radiographic examination of the feet. Which of the following radiographic findings is most indicative of navicular disease (podotrochleosis)?

Rotation and sinking of the distal phalanx (P3) within the hoof capsule.
Enlarged, flask-shaped synovial invaginations ('lollipops') on the distal border of the navicular bone. (Correct answer)
Smooth, well-defined new bone formation on the extensor process of the distal phalanx.
Narrowing of the distal interphalangeal joint space with extensive periarticular osteophytes.

Correct answer: Enlarged, flask-shaped synovial invaginations ('lollipops') on the distal border of the navicular bone.

While many radiographic changes can be seen with navicular disease, the presence of more than 6-7 enlarged, flask-shaped or branching synovial invaginations (vascular channels) on the distal border is a classic and significant finding. Other key signs include flexor cortex erosions and medullary sclerosis.

Question 144: A cat presents with pleural effusion. On thoracic radiographs, which finding best differentiates pleural effusion from pulmonary consolidation?

Loss of cardiac silhouette border
Increased opacity in the perihilar region
Retraction of lung lobes from the thoracic wall (Correct answer)
Air bronchograms within the opacity

Correct answer: Retraction of lung lobes from the thoracic wall

Pleural effusion causes lung lobes to retract away from the thoracic wall, whereas consolidated lung lobes remain in contact with the chest wall.

Question 145: A hyperthyroid cat on methimazole develops a platelet count of 40,000/µL on a CBC. What is the most appropriate next step?

Continue methimazole and recheck CBC in 2 weeks
Add prednisone to counteract methimazole-induced immune suppression
Reduce the methimazole dose by 50%
Discontinue methimazole immediately and consider radioactive iodine or surgical thyroidectomy (Correct answer)

Correct answer: Discontinue methimazole immediately and consider radioactive iodine or surgical thyroidectomy

Severe thrombocytopenia is a serious hematologic adverse effect of methimazole requiring immediate discontinuation; alternative definitive therapies should be pursued.

Question 146: A 9-year-old Golden Retriever is diagnosed with protein-losing nephropathy. UPC ratio is 4.8. Which antihypertensive class is considered first-line therapy to reduce proteinuria?

Loop diuretics
ACE inhibitors (Correct answer)
Calcium channel blockers
Beta-blockers

Correct answer: ACE inhibitors

ACE inhibitors (e.g., enalapril, benazepril) reduce glomerular capillary pressure and proteinuria and are first-line therapy for PLN.

Question 147: A 10-year-old DSH cat presents with polyuria, polydipsia, and a serum fructosamine of 285 µmol/L (reference: 190–365). Blood glucose is 14.2 mmol/L. Which interpretation is most accurate?

The fructosamine confirms sustained hyperglycemia consistent with diabetes mellitus
Fructosamine is unreliable in cats with concurrent hemolytic anemia and should be repeated
A fructosamine of 285 µmol/L is diagnostic for hyperthyroidism-induced insulin resistance
The fructosamine is within normal range, suggesting stress hyperglycemia rather than DM (Correct answer)

Correct answer: The fructosamine is within normal range, suggesting stress hyperglycemia rather than DM

Feline fructosamine reflects average glycemic control over 1–3 weeks. A value of 285 µmol/L falls within the normal reference range (190–365 µmol/L), indicating the hyperglycemia is likely transient (stress-induced) rather than sustained DM. Stress hyperglycemia is common in cats; fructosamine helps differentiate it from true DM. A fructosamine >400 µmol/L typically confirms DM. The other options misapply the reference values or attribute the finding incorrectly.

Question 148: A beef producer has a 3% calf crop loss from scours annually. To calculate the cost of a calf scours prevention program, which parameter is NOT included in the basic cost-benefit analysis?

Labor costs for treatment
Cost of the vaccine program
Value of calves saved
Breed of the dam (Correct answer)

Correct answer: Breed of the dam

Dam breed is not a direct economic variable in a cost-benefit analysis of a vaccination program; the relevant inputs are vaccine cost, calf value, morbidity/mortality rates, and treatment costs.

Question 149: A Siamese cat presents with recurrent upper respiratory signs, chronic nasal discharge, and sneezing since kittenhood. Rhinoscopy reveals mucosal proliferation and turbinate destruction. Which diagnosis is most likely?

Aspergillus rhinosinusitis
Chronic rhinosinusitis secondary to herpesvirus-1 (FHV-1) (Correct answer)
Nasal lymphoma
Cryptococcus neoformans rhinitis

Correct answer: Chronic rhinosinusitis secondary to herpesvirus-1 (FHV-1)

Chronic rhinosinusitis with turbinate destruction in young cats with a history of repeated upper respiratory infections is most commonly a sequela of early FHV-1 infection causing permanent mucosal damage.

Question 150: A 7-year-old DSH cat presents with acute dyspnea. Thoracic radiographs show a 'mediastinal mass' with a rounded soft-tissue opacity in the cranial mediastinum. Ultrasound reveals an anechoic, thin-walled structure with no internal vascularity on Doppler. Which diagnosis is MOST consistent with these findings?

Ectopic thyroid adenoma
Mediastinal cyst (branchial or thymic) (Correct answer)
Cranial mediastinal lymphoma
Chemodectoma

Correct answer: Mediastinal cyst (branchial or thymic)

Mediastinal cysts (branchial cleft or thymic remnant cysts) appear as well-defined anechoic structures with thin walls and no internal blood flow on color Doppler. Lymphoma, the most common cranial mediastinal mass in cats, typically shows heterogeneous echogenicity and detectable vascularity. Ectopic thyroid tissue and chemodectomas are vascularized solid masses. The purely anechoic, avascular ultrasound appearance is the key distinguishing feature of a benign cyst.

Question 151: Which statement correctly describes the feline estrous cycle?

Queens are induced ovulators; without mating or coital stimulation, they undergo repeated estrous cycles during the breeding season (Correct answer)
Queens are spontaneous ovulators with a 21-day cycle similar to dogs
Queens are seasonally polyestrous induced ovulators with luteal phase length of 2–3 weeks after infertile mating
Queens ovulate spontaneously mid-estrus and develop a functional CL regardless of mating

Correct answer: Queens are induced ovulators; without mating or coital stimulation, they undergo repeated estrous cycles during the breeding season

Cats are seasonally polyestrous (long-day breeders) and induced ovulators — ovulation requires coital stimulation of the vagina/cervix causing a neuroendocrine GnRH surge. Without mating, queens cycle repeatedly through estrus (lasting 4–7 days) and interestrus periods throughout the breeding season without forming a CL. If mating occurs but does not result in pregnancy, a pseudopregnancy of ~35–40 days follows.

Question 152: Which dietary management strategy implemented during the final 2-3 weeks of the dry period is most effective for preventing periparturient hypocalcemia (milk fever) in dairy cows?

Maximizing dietary potassium to improve rumen function.
Feeding a diet high in calcium to 'prime' the system.
Supplementing with high levels of intravenous calcium.
Feeding a diet with a negative Dietary Cation-Anion Difference (DCAD). (Correct answer)

Correct answer: Feeding a diet with a negative Dietary Cation-Anion Difference (DCAD).

Feeding a diet with a negative Dietary Cation-Anion Difference (DCAD), also known as an acidogenic diet, is the most effective nutritional strategy to prevent milk fever. This diet induces a mild metabolic acidosis, which improves the cow's ability to mobilize calcium from bone and absorb it from the gut in response to parathyroid hormone (PTH) when the massive demand for calcium begins at calving. Feeding high calcium pre-calving or high potassium actually increases the risk of milk fever. IV calcium is a treatment, not a preventative feeding strategy.

Question 153: A 4-year-old DSH cat is being treated for chronic pain with buprenorphine. The owner inadvertently administers a full tablet of acetaminophen (500 mg) intended for herself. Which mechanism is primarily responsible for acetaminophen toxicity in cats compared to dogs and humans?

Cats lack glutathione reductase, preventing regeneration of glutathione stores
Cats have enhanced CYP2E1 activity that produces excessive NAPQI from acetaminophen
Cats lack sufficient UDP-glucuronosyltransferase 1A6 (UGT1A6) activity to conjugate NAPQI, leading to accumulation (Correct answer)
Cats preferentially shunt acetaminophen through the sulfation pathway, producing toxic sulfate conjugates

Correct answer: Cats lack sufficient UDP-glucuronosyltransferase 1A6 (UGT1A6) activity to conjugate NAPQI, leading to accumulation

Cats are exceptionally susceptible to acetaminophen toxicity due to a genetic deficiency in UGT1A6 (and related isoforms), the glucuronidation enzyme responsible for conjugating NAPQI — the reactive intermediate produced by CYP450 metabolism of acetaminophen. Without adequate glucuronidation capacity, NAPQI accumulates, depletes glutathione, and binds covalently to hemoglobin (causing methemoglobinemia and Heinz body formation) and hepatocytes (causing hepatic necrosis). Dogs and humans can glucuronidate NAPQI efficiently; cats largely cannot. The sulfation pathway is also limited in cats and becomes quickly saturated.

Question 154: A veterinarian administers detomidine to a horse for standing sedation. This drug produces reliable sedation, muscle relaxation, and analgesia by acting as a potent agonist at which of the following receptors?

NMDA receptor
Alpha-2 adrenergic receptor (Correct answer)
GABA receptor
Mu-opioid receptor

Correct answer: Alpha-2 adrenergic receptor

Detomidine is a potent alpha-2 adrenergic agonist. Stimulation of these receptors in the central and peripheral nervous system inhibits the release of norepinephrine, which results in sedation, analgesia, and muscle relaxation. This class of drugs is commonly used for sedation in large animals.

Question 155: A 5-year-old Thoroughbred racehorse undergoes emergency surgery for a complete lateral condylar fracture of the right third metacarpal bone sustained during a race. The fracture is repaired with lag screw fixation. Three weeks postoperatively, the horse develops acute non-weight-bearing lameness and radiographs show implant loosening with bone lysis around the screw tracks. Bacterial culture of joint fluid grows Staphylococcus aureus resistant to beta-lactam antibiotics. Which systemic antibiotic protocol is most appropriate while awaiting full susceptibility results?

Chloramphenicol 50 mg/kg PO QID
Enrofloxacin 5 mg/kg IV once daily (Correct answer)
Vancomycin 7.5 mg/kg IV TID with therapeutic drug monitoring
Trimethoprim-sulfamethoxazole 30 mg/kg PO BID

Correct answer: Enrofloxacin 5 mg/kg IV once daily

Enrofloxacin is the most practical systemic option for methicillin-resistant Staphylococcus aureus (MRSA) or beta-lactam-resistant staphylococcal infections in horses pending full susceptibility data. Fluoroquinolones achieve excellent bone and synovial fluid penetration and have demonstrated efficacy against many resistant staphylococci in equine clinical practice. Vancomycin is theoretically ideal for MRSA but is nephrotoxic in horses, poorly studied pharmacokinetically, and logistically challenging (TID IV). TMP-sulfa has variable efficacy against S. aureus and poor bone penetration. Chloramphenicol has public health implications (aplastic anemia risk in humans via residues) and is rarely used in performance horses.

Question 156: Which anesthetic protocol is most commonly associated with post-anesthetic myopathy in horses undergoing prolonged recumbency?

Epidural analgesia with detomidine
Inhalant anesthesia with hypotension and poor padding (Correct answer)
Total intravenous anesthesia with ketamine-xylazine-guaifenesin
Regional nerve blocks prior to induction

Correct answer: Inhalant anesthesia with hypotension and poor padding

Post-anesthetic myopathy in horses is most strongly associated with inhalant anesthesia combined with hypotension and inadequate padding, leading to compartment syndrome of dependent muscles.

Question 157: A dairy producer wants to monitor transition cow health. Which single blood test best predicts subclinical ketosis in fresh cows?

Serum beta-hydroxybutyrate (BHB) ≥1.2 mmol/L (Correct answer)
Serum NEFA >0.4 mEq/L at dry-off only
Blood glucose <2.5 mmol/L
Urine acetone dipstick color change

Correct answer: Serum beta-hydroxybutyrate (BHB) ≥1.2 mmol/L

Serum BHB ≥1.2 mmol/L (1.0–1.4 mmol/L threshold range) measured in the first 2 weeks postpartum is the gold standard for diagnosing subclinical ketosis.

Question 158: A horse presents with chronic forelimb lameness localized to the coffin joint. Radiographs show marked osteolysis and periarticular new bone formation. Synoviocentesis yields thick, turbid fluid with 85,000 WBC/μL (>90% neutrophils) and a glucose concentration much lower than serum. What is the next most critical step?

Initiate systemic corticosteroids
Repeat radiographs in 2 weeks
Perform through-and-through joint lavage and systemic antimicrobials (Correct answer)
Perform arthroscopic debridement under general anesthesia immediately without lavage

Correct answer: Perform through-and-through joint lavage and systemic antimicrobials

Septic arthritis requires immediate joint lavage (through-and-through or arthroscopic) combined with systemic and intra-articular antimicrobials to remove bacteria and inflammatory mediators.

Question 159: A 4-year-old Soft Coated Wheaten Terrier is presented for chronic small bowel diarrhea, significant weight loss, and peripheral edema. Bloodwork reveals severe panhypoproteinemia (both albumin and globulin are low). Which of the following conditions is the most likely underlying cause?

Protein-losing enteropathy (PLE) (Correct answer)
Exocrine pancreatic insufficiency (EPI)
Chronic hepatitis
Protein-losing nephropathy

Correct answer: Protein-losing enteropathy (PLE)

The combination of chronic diarrhea, weight loss, and panhypoproteinemia (low albumin and globulin) is characteristic of a protein-losing enteropathy (PLE). In PLE, proteins are lost through the gastrointestinal tract. While protein-losing nephropathy and chronic hepatitis cause hypoalbuminemia, globulins are typically normal or elevated. EPI causes weight loss and diarrhea but does not typically cause significant protein loss. Soft Coated Wheaten Terriers are also predisposed to PLE.

Question 160: A 5-year-old Labrador Retriever is presented with acute collapse and hematemesis. On exam, the dog is tachycardic (HR 160 bpm), pale, and has a fluid wave on abdominal ballottement. PCV is 18%, total protein is 3.2 g/dL, and abdominal ultrasound reveals a large splenic mass with free abdominal fluid. After stabilization, a splenectomy is performed. Histopathology confirms splenic hemangiosarcoma. Which combination of prognostic factors is associated with the LONGEST median survival time post-splenectomy?

Stage III disease with adjuvant metronomic cyclophosphamide
Stage I disease with no adjuvant therapy
Stage II disease with adjuvant vincristine, doxorubicin, and cyclophosphamide (VAC)
Stage I disease with adjuvant doxorubicin chemotherapy (Correct answer)

Correct answer: Stage I disease with adjuvant doxorubicin chemotherapy

Splenic hemangiosarcoma staged as Stage I (tumor confined to spleen, no rupture, no metastasis) combined with adjuvant doxorubicin-based chemotherapy is associated with the longest median survival — approximately 4–6 months compared to 1–2 months with surgery alone. Stage II (ruptured or with regional spread) and Stage III (distant metastasis) carry significantly worse prognoses regardless of protocol. VAC has not consistently outperformed single-agent doxorubicin in canine HSA.

Question 161: In llamas, the most typical source of bony facial tumors is

Tooth root abscess (Correct answer)
Osteomyelitis
Ossifying fibroma
Facial bone fracture

Correct answer: Tooth root abscess

In llamas, tooth root abscesses are a very common cause of bony facial tumors or swellings. The infection and inflammation associated with an abscess can lead to significant osteomyelitis and reactive bone proliferation in the surrounding facial bones. This presents as a firm, bony mass, making tooth root abscesses the most frequent etiology for such lesions in this species.

Question 162: A 35 kg Labrador Retriever is receiving a morphine CRI at 0.1 mg/kg/hr post-orthopedic surgery. Six hours postoperatively, the dog is dysphoric, vocalizing, scratching at the face, and mildly ataxic, with a heart rate of 58 bpm. The MOST appropriate next step is:

Administer low-dose naloxone 0.002 mg/kg IV and reassess pain score (Correct answer)
Administer naloxone 0.04 mg/kg IV to reverse opioid toxicity
Switch to a fentanyl CRI and add acepromazine 0.02 mg/kg for sedation
Increase the morphine CRI to 0.2 mg/kg/hr to deepen analgesia

Correct answer: Administer low-dose naloxone 0.002 mg/kg IV and reassess pain score

The clinical picture—dysphoria, facial scratching (opioid-induced pruritus), ataxia, and bradycardia—represents morphine-induced side effects rather than undertreated pain. Full reversal with a standard naloxone dose (0.04 mg/kg) would eliminate analgesia, causing acute pain rebound. Low-dose naloxone (0.001–0.004 mg/kg IV) selectively reverses side effects such as dysphoria, pruritus, and excessive sedation while largely preserving analgesic efficacy. Increasing the CRI would worsen the side effect profile. Acepromazine can deepen sedation but does not address the underlying opioid-mediated dysphoria and may mask neurologic deterioration.

Question 163: When evaluating a horse for subtle hindlimb lameness, which surface is MOST useful for accentuating the gait abnormality?

Grass pasture
Soft, deep sand arena (Correct answer)
Rubber-matted stall aisle
Firm, level asphalt surface

Correct answer: Soft, deep sand arena

A soft, deep surface increases concussion and proprioceptive demands on the hindlimb, accentuating subtle lameness signs that may not be visible on a firmer surface.

Question 164: A 7-year-old Poodle presents with a PCV of 18%, MCV of 110 fL (macrocytosis), and a low serum cobalamin (B12). What is the most likely cause?

Iron deficiency anemia
Cobalamin deficiency causing megaloblastic anemia (Correct answer)
Chronic disease anemia
Feline leukemia virus-like anemia

Correct answer: Cobalamin deficiency causing megaloblastic anemia

Cobalamin deficiency impairs DNA synthesis in RBC precursors, causing large, immature red cells (macrocytosis) and non-regenerative megaloblastic anemia.

Question 165: On thoracic radiographs of a dog, you notice the cardiac silhouette occupies more than 75% of the thoracic width on the VD view. What does this most likely indicate?

Pulmonary consolidation
Cardiomegaly (Correct answer)
Pleural effusion
Pneumothorax

Correct answer: Cardiomegaly

A cardiac silhouette exceeding 75% of thoracic width on the VD view is consistent with cardiomegaly.

Question 166: Which of the following is the most critical component of a biosecurity program to prevent the introduction of infectious diseases into a closed beef cow-calf herd?

Testing and quarantining all newly purchased animals. (Correct answer)
Maintaining a double-fenced perimeter to prevent nose-to-nose contact.
Vaccinating the resident herd for all common regional diseases.
Requiring all visitors to wear disposable plastic boots.

Correct answer: Testing and quarantining all newly purchased animals.

The introduction of new animals poses the highest risk for introducing new pathogens into an established herd. A strict protocol of testing for key diseases and quarantining new animals for a minimum of 30 days is the most critical biosecurity measure. This allows for observation, acclimatization, and re-testing before commingling. While other measures like visitor protocols and boundary fences are important parts of a comprehensive biosecurity plan, they are secondary to managing the risk from new animal introductions.

Question 167: A veterinarian discharges a post-obstructed cat with buprenorphine prescribed for sublingual (oral transmucosal) administration at home. She explains to the owner that this route achieves good bioavailability in cats but would not work nearly as well if given the same way to a dog. Which physiological property of cats most directly explains this species difference in sublingual buprenorphine absorption?

Cats have a significantly higher density of mu-opioid receptors in the buccal mucosa, enabling receptor-mediated transcytosis of buprenorphine
Cats express lower levels of P-glycoprotein efflux pumps in oral epithelium, reducing active buprenorphine efflux back into the oral cavity
Feline sublingual vasculature bypasses hepatic first-pass metabolism via direct lymphatic drainage into the thoracic duct
The alkaline salivary pH in cats (~8.5–9.0) maintains buprenorphine predominantly in its non-ionized, lipid-soluble form, facilitating passive mucosal absorption (Correct answer)

Correct answer: The alkaline salivary pH in cats (~8.5–9.0) maintains buprenorphine predominantly in its non-ionized, lipid-soluble form, facilitating passive mucosal absorption

Cats have an alkaline oral/salivary pH of approximately 8.5–9.0, which is close to buprenorphine's pKa (~8.24). At this pH, a substantial proportion of buprenorphine molecules are in the non-ionized, lipid-soluble form that readily crosses lipid bilayer membranes — achieving approximately 38–53% bioavailability via the oral transmucosal route. In dogs, the more acidic oral pH (~7.5) shifts the equilibrium toward the ionized, water-soluble form that poorly penetrates mucosa, making sublingual administration ineffective. This is a key pharmacokinetic reason why OTM buprenorphine is a practical analgesic route in cats but not dogs.

Question 168: A cat presents with acute-onset ptyalism, vomiting, ataxia, and mydriasis after being seen chewing on a lily bouquet. Bloodwork 36 hours later reveals a BUN of 98 mg/dL and creatinine of 7.2 mg/dL. Which statement BEST describes the mechanism of lily nephrotoxicity in cats?

The toxic glycoside tuliposide A is activated in the renal cortex and alkylates mitochondrial DNA of tubular cells
Lily stamen pollen contains calcium oxalate crystals that deposit in renal tubules and cause obstructive nephropathy
The nephrotoxic principle causes direct proximal tubular epithelial cell death via a mechanism not yet fully elucidated at the molecular level, with no known antidote (Correct answer)
Lycorine alkaloids found in Lilium species competitively inhibit renal organic anion transporters, causing tubular toxin accumulation

Correct answer: The nephrotoxic principle causes direct proximal tubular epithelial cell death via a mechanism not yet fully elucidated at the molecular level, with no known antidote

True lily nephrotoxicity (Lilium and Hemerocallis species) in cats is a well-documented but mechanistically incompletely understood toxidrome. The toxic principle causes acute, severe proximal tubular necrosis, but the exact molecular mechanism has not been definitively identified in peer-reviewed literature. There is no antidote — treatment is aggressive IV fluid diuresis initiated within hours of exposure, before renal injury is established. Calcium oxalate crystals causing obstructive nephropathy are associated with Oxalis and Araceae species (e.g., Philodendron, Dieffenbachia), not true lilies. Lycorine is found in Narcissus/Amaryllidaceae; tuliposide A is found in Tulipa. Cats are uniquely and exquisitely sensitive to Lilium/Hemerocallis; dogs are not.

Question 169: Abdominal ultrasound in a 6-year-old Labrador Retriever reveals a splenic mass with a heterogeneous echotexture containing multiple anechoic cavities and hyperechoic foci casting acoustic shadowing. The surrounding parenchyma shows a 'Swiss cheese' appearance. Which diagnosis does this pattern MOST strongly suggest?

Splenic abscess
Splenic myelolipoma (Correct answer)
Splenic hemangiosarcoma
Nodular splenic hyperplasia

Correct answer: Splenic myelolipoma

Splenic myelolipomas contain mature myeloid elements and adipose tissue, producing a characteristic ultrasound pattern: heterogeneous mass with hyperechoic foci (fat) that may shadow, intermixed anechoic areas, and a 'Swiss cheese' or honeycomb appearance of the splenic parenchyma. Hemangiosarcoma is typically hyperechoic or heterogeneous with blood-filled cavities but lacks the fat-related shadowing foci. Nodular hyperplasia appears as discrete, well-defined hypoechoic nodules. Splenic abscesses can be complex but are associated with clinical signs of sepsis and lack the fat-shadowing component. Myelolipomas are incidental benign lesions.

Question 170: A cat anesthetized with ketamine/diazepam develops prolonged apnea after induction. Which characteristic of ketamine best explains this risk?

Ketamine causes dose-dependent respiratory depression at high doses (Correct answer)
Ketamine inhibits NMDA receptors in the brainstem
Ketamine stimulates mu-opioid receptors
Ketamine increases upper airway secretions causing obstruction

Correct answer: Ketamine causes dose-dependent respiratory depression at high doses

While ketamine is generally considered a respiratory-sparing agent, high or rapidly administered doses can cause dose-dependent apnea in cats.

Question 171: A 3-year-old intact male ferret presents with insulinoma-related hypoglycemia. The clinician elects to use diazoxide as medical management. Which mechanism of action makes diazoxide appropriate for this condition?

It opens ATP-sensitive potassium channels in pancreatic beta cells, hyperpolarizing the membrane and inhibiting insulin release (Correct answer)
It competitively inhibits glucokinase in beta cells, reducing glucose-stimulated insulin secretion
It blocks GLUT-2 transporters in beta cells, preventing glucose sensing and suppressing insulin secretion
It stimulates hepatic glycogenolysis via glucagon receptor agonism, raising blood glucose independent of insulin

Correct answer: It opens ATP-sensitive potassium channels in pancreatic beta cells, hyperpolarizing the membrane and inhibiting insulin release

Diazoxide acts by opening ATP-sensitive potassium channels (K-ATP channels) in pancreatic beta cells. This hyperpolarizes the cell membrane, preventing calcium influx through voltage-gated calcium channels, and thereby inhibiting insulin exocytosis. This directly counteracts the excessive autonomous insulin secretion from insulinoma cells. In contrast, sulfonylureas (like glipizide) close these same K-ATP channels, stimulating insulin release — making them contraindicated in insulinoma. Glucokinase inhibition, GLUT-2 blockade, or glucagon receptor agonism are not diazoxide's mechanisms.

Question 172: Which of the following is the preferred site for intravenous catheter placement in a rabbit?

Jugular vein
Marginal ear vein (Correct answer)
Cephalic vein
Lateral saphenous vein

Correct answer: Marginal ear vein

The marginal ear vein is the most accessible and commonly used IV catheter site in rabbits due to its visibility and ease of access.

Question 173: During anesthesia of a ball python for surgical removal of a retained spectacle, the veterinarian notes apnea persisting more than 10 minutes after isoflurane is discontinued. Which of the following BEST explains why reptiles are particularly susceptible to prolonged post-anesthetic apnea compared to mammals?

Reptiles have a higher metabolic rate and consume anesthetic agents more rapidly, leading to prolonged tissue saturation
Reptiles have a tripartite heart with significant right-to-left cardiac shunting that recirculates anesthetic vapor and delays washout
The reptilian lung has a more extensive blood-gas barrier that delays anesthetic elimination via pulmonary routes
Reptiles rely primarily on peripheral chemoreceptors sensitive to PO2 rather than central CO2/pH-driven ventilatory drive, making hypercapnia a poor respiratory stimulus (Correct answer)

Correct answer: Reptiles rely primarily on peripheral chemoreceptors sensitive to PO2 rather than central CO2/pH-driven ventilatory drive, making hypercapnia a poor respiratory stimulus

Reptiles have a blunted central chemoreceptor response to hypercapnia compared to mammals. Their ventilatory drive depends more on peripheral oxygen sensing, and they tolerate wide swings in PCO2 with minimal respiratory response. This means rising CO2 after anesthesia does not reliably stimulate breathing, causing prolonged apnea. The cardiac shunt (option D) contributes to anesthetic uptake/elimination differences but is not the primary reason for post-anesthetic apnea.

Question 174: Ovine Progressive Pneumonia (OPP) caused by Maedi-Visna virus is best controlled in a flock through which strategy?

Prophylactic long-term tetracycline administration in feed
Test-and-cull seropositive animals combined with separating lambs from seropositive ewes at birth (Correct answer)
Annual vaccination with killed-virus OPP vaccine
Parenteral ivermectin to eliminate the arthropod vector

Correct answer: Test-and-cull seropositive animals combined with separating lambs from seropositive ewes at birth

Maedi-Visna/OPP is a lentiviral infection with no vaccine or cure. Control relies on identifying seropositive animals via AGID or ELISA and removing them, combined with preventing transmission to lambs via infected colostrum/milk by separating and heat-treating or discarding colostrum. There is no arthropod vector; it is spread by close contact and milk.

Question 175: A dog with dilated cardiomyopathy is started on digoxin. Which electrolyte abnormality increases the risk of digoxin toxicity?

Hypercalcemia
Hypokalemia (Correct answer)
Hypernatremia
Hyperkalemia

Correct answer: Hypokalemia

Hypokalemia potentiates digoxin toxicity because potassium and digoxin compete for the same binding site on Na+/K+-ATPase; low potassium increases digoxin binding and effect.

Question 176: Ketamine is commonly used as an induction agent, particularly in cats. What is its PRIMARY mechanism of anesthetic action?

Alpha-2 adrenergic agonism
GABA-A receptor potentiation
Mu-opioid receptor agonism
NMDA receptor antagonism (Correct answer)

Correct answer: NMDA receptor antagonism

Ketamine produces dissociative anesthesia primarily by non-competitive antagonism of NMDA (N-methyl-D-aspartate) glutamate receptors, which also contributes to its analgesic properties.

Question 177: A veterinary public health officer is reviewing a HACCP plan for a federally inspected poultry slaughter establishment. The establishment proposes a single critical control point (CCP) — post-chill chlorinated water immersion at 50 ppm — for Salmonella control. Which of the following is the most accurate assessment of this plan's adequacy under current USDA-FSIS regulations?

The plan is inadequate; FSIS requires pathogen reduction performance standards for Salmonella that must be validated with microbial testing data, and a single post-chill intervention without upstream interventions (ante-mortem, scalding, defeathering CCPs) is unlikely to meet the Salmonella performance standard for broilers (Correct answer)
The plan is adequate; 50 ppm chlorine post-chill is an FSIS-approved intervention that satisfies all Salmonella performance standards when properly monitored
The plan is adequate but only if the establishment also maintains an antimicrobial resistance monitoring program under the National Antimicrobial Resistance Monitoring System (NARMS)
The plan is inadequate solely because FSIS prohibits chlorine concentrations above 20 ppm in immersion chillers under the Federal Food, Drug, and Cosmetic Act

Correct answer: The plan is inadequate; FSIS requires pathogen reduction performance standards for Salmonella that must be validated with microbial testing data, and a single post-chill intervention without upstream interventions (ante-mortem, scalding, defeathering CCPs) is unlikely to meet the Salmonella performance standard for broilers

FSIS mandates Salmonella performance standards (9 CFR Part 381) requiring establishments to demonstrate through microbial sampling that their process consistently produces product meeting the standard. A HACCP plan must be validated — meaning the establishment must show the CCP actually achieves the food safety objective. A single post-chill CCP is generally insufficient because a multi-hurdle approach (scalding temperature, inside-outside bird washer, antimicrobial rinses at multiple points) is needed to achieve meaningful log reductions. FSIS allows chlorine up to 20 ppm in water that contacts carcasses for human consumption without rinsing, but chiller water at higher concentrations with rinsing is managed under different tolerances — the regulatory limit issue is real but secondary to the validation inadequacy. NARMS participation is voluntary.

Question 178: A dog's abdominal ultrasound reveals a splenic mass with a 'target' or 'bull's-eye' lesion appearance (hypoechoic halo around a hyperechoic center). This pattern is most associated with:

Splenic hematoma
Splenic abscess
Metastatic neoplasia (Correct answer)
Nodular hyperplasia

Correct answer: Metastatic neoplasia

A target or bull's-eye lesion pattern in the spleen is classically associated with metastatic disease, where a necrotic center is surrounded by viable tumor tissue.

Question 179: A cat is presented for evaluation of recurrent upper respiratory signs and oral ulcerations. FHV-1 PCR is positive on conjunctival swab. Which of the following statements about feline herpesvirus-1 pathophysiology is MOST accurate?

Latency is established exclusively in trigeminal ganglia, and reactivation consistently produces clinical disease
Latency is established in trigeminal ganglia; reactivation may be subclinical and shedding can occur without overt signs (Correct answer)
The virus establishes persistent viremia, making antigen testing on serum the preferred diagnostic method
Antiviral treatment with famciclovir eliminates latent virus and prevents future recurrence

Correct answer: Latency is established in trigeminal ganglia; reactivation may be subclinical and shedding can occur without overt signs

FHV-1 establishes latency primarily in the trigeminal ganglia. Reactivation, triggered by stress or immunosuppression, does not always produce overt clinical disease — cats can shed virus asymptomatically, which has significant implications for multi-cat environments. Persistent viremia does not occur; PCR on conjunctival or nasal swabs is the preferred diagnostic approach. Famciclovir reduces viral replication and severity of clinical signs but does not eliminate latent virus — recurrence remains possible.

Question 180: A 5-year-old male Dalmatian presents with recurrent urinary tract infections and struvite uroliths. Urate crystals are also identified on urinalysis. Which metabolic defect predisposes Dalmatians to urate urolithiasis?

Increased xanthine oxidase activity
Reduced hepatic conversion of uric acid to allantoin (Correct answer)
Impaired renal tubular secretion of allantoin
Deficiency of uricase enzyme

Correct answer: Reduced hepatic conversion of uric acid to allantoin

Dalmatians have impaired hepatic conversion of uric acid to allantoin and reduced renal tubular reabsorption of urate, leading to uric acid excretion and urate uroliths.

Question 181: A 5-year-old Poodle presents with acute collapse, pale mucous membranes, and distended abdomen. Ultrasound reveals a large hepatic mass with free abdominal fluid. Which tumor is most commonly associated with hemoabdomen in dogs?

Lymphoma
Hepatocellular carcinoma
Mast cell tumor
Hemangiosarcoma (Correct answer)

Correct answer: Hemangiosarcoma

Hemangiosarcoma of the spleen or liver is the most common cause of spontaneous hemoabdomen in dogs due to its highly vascular and fragile nature.

Question 182: Which serum biomarker is most specific for acute pancreatitis diagnosis in cats?

Feline pancreatic lipase immunoreactivity (fPLI/Spec fPL) (Correct answer)
Serum lipase
Serum amylase
Serum trypsin-like immunoreactivity (fTLI)

Correct answer: Feline pancreatic lipase immunoreactivity (fPLI/Spec fPL)

Feline pancreatic lipase immunoreactivity (Spec fPL) is the most sensitive and specific biomarker for pancreatitis diagnosis in cats, unlike amylase and lipase which lack specificity.

Question 183: A 4-year-old Quarter Horse shows reluctance to extend the left forelimb fully when walking. On observation, there is a characteristic 'catching' of the hindlimb with the hoof dragging during protraction. Which condition best explains the hindlimb gait abnormality?

Stringhalt (Australian stringhalt)
Upward fixation of the patella
Fibrotic myopathy of the semitendinosus/semimembranosus (Correct answer)
Shivers

Correct answer: Fibrotic myopathy of the semitendinosus/semimembranosus

Fibrotic myopathy following injury to the caudal thigh muscles causes a characteristic mechanical gait with a sudden caudal 'flip' of the foot during the cranial phase of the stride.

Question 184: An 8-month-old kitten presents with intention tremors of the head, broad-based stance, hypermetria, and falling toward the right. The neurologic examination is otherwise normal with no weakness. Which region of the nervous system is affected?

Right cerebral hemisphere (forebrain)
Right side of the cerebellum (Correct answer)
Right C1-C5 spinal cord segment
Right vestibular apparatus (peripheral)

Correct answer: Right side of the cerebellum

Intention tremors, hypermetria, and broad-based stance without weakness are signs of cerebellar disease. Falling/rolling ipsilaterally (toward the lesion side) with a unilateral cerebellar lesion reflects ipsilateral cerebellar hemispheric dysfunction (cerebellum has ipsilateral control). Forebrain lesions cause contralateral deficits with normal gait quality. Peripheral vestibular disease causes head tilt and nystagmus without hypermetria or intention tremor.

Question 185: An eight-year-old thoroughbred mare with a one-year history of infertility and unusual aggressive behavior is being assessed. Except for an enlarged ovary felt during a rectal exam, physical exam findings are normal. The enlarged ovary seems multiloculated according to ultrasonography. Which of the following tests is the most reliable predictor of the prevailing diagnosis when elevated?

Inhibin (Correct answer)
Estrogen
Progesterone
FSH

Correct answer: Inhibin

The clinical signs of infertility and aggressive behavior in an 8-year-old mare, combined with an enlarged, multiloculated ovary, are highly suggestive of a granulosa cell tumor (GCT). Granulosa cell tumors are the most common ovarian tumor in mares and often produce hormones, including inhibin, testosterone, and estrogen. Elevated inhibin levels are the most reliable diagnostic marker for GCTs in mares, as it is produced by the granulosa cells of the tumor and suppresses FSH.

Question 186: A dog that has been struck by a car typically has non-weight-bearing foreleg lameness. Physical examination reveals no fractures that can be felt. Without any movement or pain, the limb simply hangs there. It is also discovered that the dog has Horner's syndrome. What medical condition is most likely to account for these exam results?

Cervical disc disease
Arterial thromboembolism
Brachial plexus avulsion (Correct answer)
Radial nerve paralysis

Correct answer: Brachial plexus avulsion

The combination of non-weight-bearing foreleg lameness, a flaccid limb that 'just hangs there,' and the presence of Horner's syndrome is highly indicative of a brachial plexus avulsion. Horner's syndrome (miosis, ptosis, enophthalmos) occurs due to damage to sympathetic nerve fibers within the brachial plexus. The flaccid paralysis results from severe nerve root damage, typically from a traumatic pull on the limb.

Question 187: In equine radiography, 'rotation' of the distal phalanx relative to the hoof wall is measured by which imaging technique?

Ultrasound of the deep digital flexor tendon
Dorsopalmar radiograph of the foot
Nuclear scintigraphy of the foot
Lateral radiograph with a reference marker on the dorsal hoof wall (Correct answer)

Correct answer: Lateral radiograph with a reference marker on the dorsal hoof wall

Lateral radiographs with a radio-opaque marker placed on the dorsal hoof wall allow measurement of the palmar angle and rotation of P3 in laminitic horses.

Question 188: Which clinical sign most distinguishes feline metaldehyde (slug bait) toxicity from other tremorgenic toxicoses?

Hyperthermia is the predominant presenting sign
Signs are worsened by sensory stimulation
Mydriasis and tachycardia are the first signs
Cats display continuous violent muscle tremors that are difficult to control (Correct answer)

Correct answer: Cats display continuous violent muscle tremors that are difficult to control

Metaldehyde causes severe, relentless muscle tremors due to GABA inhibition; signs are often refractory to benzodiazepines alone.

Question 189: A horse presents with a sudden onset of severe, non-weight bearing lameness of the left hindlimb. The tarsocrural joint is markedly distended, warm, and painful on palpation. Arthrocentesis reveals a turbid, yellow synovial fluid with a total protein of 5.2 g/dL and a nucleated cell count of 95,000 cells/µL, with 92% neutrophils. What is the most critical and effective treatment for this condition?

Application of a cast and long-term NSAID administration
Systemic antibiotics and stall rest alone
Intra-articular corticosteroids and bandaging
Joint lavage and systemic broad-spectrum antibiotics (Correct answer)

Correct answer: Joint lavage and systemic broad-spectrum antibiotics

The clinical signs and synovial fluid analysis are indicative of septic arthritis, a true medical emergency in horses. The cornerstone of successful treatment is aggressive and immediate intervention to eliminate the infection and remove inflammatory mediators from the joint. This is best accomplished through joint lavage (flushing the joint with large volumes of sterile fluid), often performed arthroscopically, combined with systemic broad-spectrum antibiotics. Administering only systemic antibiotics is insufficient, and intra-articular corticosteroids are contraindicated in the face of infection.

Question 190: A 10-year-old Quarter Horse presents with a chronic, intermittent, bilateral forelimb lameness that worsens on hard surfaces. The horse points the affected feet and shows a shortened cranial phase of the stride. Hoof tester application across the heels elicits a painful response. A palmar digital nerve block significantly improves the lameness. Which of the following is the most likely diagnosis?

Sole abscess
Coffin joint septic arthritis
Navicular syndrome (Correct answer)
Laminitis

Correct answer: Navicular syndrome

Navicular syndrome is a chronic degenerative condition affecting the navicular bone and associated soft tissue structures in the heel of the foot. The clinical signs described—chronic bilateral forelimb lameness, pointing, pain on hoof testers over the heel, and improvement with a palmar digital nerve block—are all classic indicators of this condition. While other conditions can cause heel pain, the chronicity and bilateral nature strongly suggest navicular syndrome.

Question 191: A beef operation loses 3 cows to sudden death with no premonitory signs. Necropsy reveals a 'paint-brush' hemorrhage pattern on the heart and rapid bloat. Which clostridial disease is most likely?

Blackleg (Clostridium chauvoei) (Correct answer)
Malignant edema (Clostridium septicum)
Black disease (Clostridium novyi type B)
Enterotoxemia type D (Clostridium perfringens)

Correct answer: Blackleg (Clostridium chauvoei)

Blackleg (C. chauvoei) classically affects young cattle 6–24 months, causing myonecrosis with rapid death and characteristic crepitant swellings and myocardial hemorrhage.

Question 192: During recovery from general anesthesia following orthopedic surgery, a horse makes multiple violent attempts to stand and sustains a fracture of the contralateral limb. This type of complication is best prevented by which approach?

Using an assisted recovery system (head/tail ropes) with quiet, padded recovery stall (Correct answer)
Prolonging anesthesia until the horse is fully awake
Placing the horse in dorsal recumbency during recovery
Administering acepromazine immediately post-surgery

Correct answer: Using an assisted recovery system (head/tail ropes) with quiet, padded recovery stall

Assisted recovery using head and tail ropes in a well-padded, quiet stall helps guide the horse to a controlled, coordinated standing position, minimizing the risk of fractures and post-anesthetic myopathy.

Question 193: A 7-year-old cat presents with icterus, anemia, and splenomegaly. Blood smear shows intraerythrocytic organisms. Which organism is most likely responsible?

Mycoplasma haemofelis (Correct answer)
Babesia felis
Cytauxzoon felis
Bartonella henselae

Correct answer: Mycoplasma haemofelis

Mycoplasma haemofelis (formerly Haemobartonella felis) is the most common cause of feline infectious anemia, attaching to the surface of red blood cells.

Question 194: A 7-year-old intact male Labrador Retriever presents with a 3-week history of progressive pelvic limb weakness, fecal tenesmus, and perineal swelling. Rectal palpation reveals a large, doughy mass lateral to the rectum that deviates it medially. Urinalysis shows isosthenuria. Which of the following is the MOST likely cause of the isosthenuria in this patient?

Concurrent benign prostatic hyperplasia compressing the urethra and leading to hydronephrosis
Paraneoplastic syndrome from a perianal adenocarcinoma causing hypercalcemia-induced nephrogenic diabetes insipidus
Retroflexion of the urinary bladder into the perineal hernia causing partial urethral obstruction and post-renal azotemia (Correct answer)
Age-related chronic interstitial nephritis as an incidental finding unrelated to the perineal mass

Correct answer: Retroflexion of the urinary bladder into the perineal hernia causing partial urethral obstruction and post-renal azotemia

Perineal hernias in intact male dogs can lead to retroflexion of the urinary bladder into the hernia sac. When the bladder retroflexes, the urethra becomes kinked or obstructed at an abnormal angle, causing post-renal azotemia and secondary isosthenuria due to medullary washout from the obstructive uropathy. This is a life-threatening complication requiring emergency surgical reduction. Benign prostatic hyperplasia is unlikely to cause hydronephrosis acutely, and perianal adenocarcinomas (rather than adenomas) secrete PTHrP — but the scenario describes a perineal hernia anatomy, not a perianal tumor. The isosthenuria in this context is mechanistically linked to the hernia complication.

Question 195: Which finding on thoracic radiographs of a cat is MOST suggestive of hypertrophic cardiomyopathy (HCM)?

Globoid cardiac silhouette with loss of cardiac waist
Right-sided cardiomegaly with increased sternal contact
Microcardia with retraction of lung lobes
Valentine-shaped heart on VD view with left atrial enlargement (Correct answer)

Correct answer: Valentine-shaped heart on VD view with left atrial enlargement

HCM in cats classically produces a Valentine or bivalve-shaped cardiac silhouette on the VD view due to biatrial enlargement.

Question 196: Which preanesthetic agent has the LEAST cardiovascular depression and is therefore most appropriate in critically ill or hemodynamically unstable patients?

Acepromazine
Xylazine
Medetomidine
Midazolam (Correct answer)

Correct answer: Midazolam

Midazolam and other benzodiazepines have minimal cardiovascular effects, making them preferred preanesthetic agents for critically ill, geriatric, or hemodynamically compromised patients.

Question 197: A cow presents with acute right-sided abomasal displacement progressing to volvulus (RDA/RAV) in a freshly calved dairy cow. Which finding on physical exam is most consistent with this diagnosis?

Left-sided ping in the paralumbar fossa on simultaneous auscultation and percussion
High-pitched ping over a large area on the right side between ribs 9-12, with signs of toxemia and tachycardia (Correct answer)
Bilateral pings with fluid splashing sounds in the lower abdomen
Left-sided rumen atony with no ping detected

Correct answer: High-pitched ping over a large area on the right side between ribs 9-12, with signs of toxemia and tachycardia

Right abomasal volvulus produces a large-area right-sided ping (ribs 9-12), signs of severe toxemia, tachycardia, and rapid cardiovascular deterioration due to venous outflow obstruction.

Question 198: Which of the following best describes the concept of 'One Health' in veterinary public health?

A global treaty requiring nations to report animal disease outbreaks within 24 hours
A single federal agency overseeing all animal and human health programs
An integrated approach recognizing the interconnection of human, animal, and environmental health (Correct answer)
A standardized vaccination protocol applied to all domestic species

Correct answer: An integrated approach recognizing the interconnection of human, animal, and environmental health

One Health is a collaborative, multisectoral approach recognizing that human, animal, and environmental health are interdependent.

Question 199: Botulism outbreaks associated with commercially processed foods typically involve which form of Clostridium botulinum toxin production?

Intestinal toxicoinfection in infants consuming spores
Iatrogenic botulism from therapeutic injections
Wound botulism from contaminated soil
Preformed toxin ingestion from improperly processed low-acid canned foods (Correct answer)

Correct answer: Preformed toxin ingestion from improperly processed low-acid canned foods

Foodborne botulism typically results from ingestion of preformed toxin in low-acid, anaerobic environments created by improper canning processes.

Question 200: Which antiparasitic drug has a narrow safety margin in cats and can cause mydriasis, ataxia, tremors, and death if overdosed, particularly in debilitated individuals?

Praziquantel
Fenbendazole
Ivermectin (Correct answer)
Selamectin

Correct answer: Ivermectin

Ivermectin toxicity in cats causes CNS signs by enhancing GABA-mediated inhibition; cats lack MDR1 mutation but are still sensitive to overdose.

Question 201: Cunean bursitis in horses with bone spavin is associated with inflammation of which structure?

Calcaneal bursa
Navicular bursa of the hind foot
Bicipital bursa of the shoulder
Bursa beneath the cunean (medial) branch of the cranial tibial tendon (Correct answer)

Correct answer: Bursa beneath the cunean (medial) branch of the cranial tibial tendon

Cunean bursitis involves the bursa located beneath the cunean branch of the cranial tibial tendon as it crosses the medial aspect of the hock, often concurrent with bone spavin.

Question 202: During a herd health visit to a 600-head beef cow-calf operation, you identify an outbreak of respiratory disease in calves 3–8 weeks of age. Morbidity is 28% and case-fatality rate is 9%. Nasal swabs from 6 acutely affected calves yield Mannheimia haemolytica in 4 and Histophilus somni in 2. Colostrum management records are excellent. Which pathogen-level finding MOST strongly suggests a vaccine-preventable gap in this herd's prevention program?

Bovine respiratory syncytial virus (BRSV) antigen detected on immunofluorescence of nasal swabs (Correct answer)
Pasteurella multocida type A isolated from a calf that died despite florfenicol treatment
Histophilus somni isolation in calves 3–8 weeks of age with neurological signs
Mannheimia haemolytica isolation in calves under 3 weeks of age

Correct answer: Bovine respiratory syncytial virus (BRSV) antigen detected on immunofluorescence of nasal swabs

BRSV is a primary viral pathogen in young calves that acts as a 'door-opener' for secondary bacterial pneumonia by disrupting mucociliary clearance and innate immunity. Its presence in calves this age with high morbidity despite good colostrum transfer points directly to a gap in dam vaccination (modified-live BRSV given pre-calving provides colostral antibody protection) or to inadequate calf vaccination timing. Mannheimia and Histophilus are secondary bacterial opportunists commonly cultured from BRD cases regardless of vaccination status. Pasteurella multocida type A treatment failure most suggests antimicrobial resistance or inadequate drug selection, not a specific vaccine gap.

Question 203: Organophosphate toxicity in animals is treated with which combination of drugs?

Naloxone and flumazenil
Physostigmine and diazepam
Atropine and pralidoxime (2-PAM) (Correct answer)
Pralidoxime (2-PAM) alone

Correct answer: Atropine and pralidoxime (2-PAM)

Atropine blocks muscarinic signs of organophosphate toxicity while pralidoxime reactivates acetylcholinesterase if given early before 'aging' of the enzyme occurs.

Question 204: A cat presents with acute onset of hindlimb paralysis, cold limbs, and absent femoral pulses. What is the most likely diagnosis?

Traumatic spinal cord injury
Intervertebral disc disease
Fibrocartilaginous embolism
Aortic thromboembolism (Correct answer)

Correct answer: Aortic thromboembolism

Aortic thromboembolism (saddle thrombus) classically presents in cats with acute hindlimb paresis/paralysis, cold extremities, and absent femoral pulses, often secondary to cardiomyopathy.

Question 205: A new pen-side antigen test for Bovine Respiratory Syncytial Virus (BRSV) is evaluated in a group of 300 calves. The results are as follows: 85 calves that are truly positive for BRSV test positive. 190 calves that are truly negative for BRSV test negative. 15 truly positive calves test negative. 10 truly negative calves test positive. What is the specificity of this new test?

85.0%
90.9%
91.7%
95.0% (Correct answer)

Correct answer: 95.0%

Specificity measures a test's ability to correctly identify disease-free individuals. The formula is: Specificity = [True Negatives / (True Negatives + False Positives)] * 100. In this scenario, the True Negatives are 190 and the False Positives are 10. Therefore, Specificity = [190 / (190 + 10)] * 100 = [190 / 200] * 100 = 95.0%.

Question 206: A 7-year-old intact male Boxer with a known history of dilated cardiomyopathy requires anesthesia for a splenic mass removal. Which induction protocol is MOST appropriate to minimize myocardial depression while providing adequate anesthesia depth?

Propofol 4 mg/kg IV bolus followed by isoflurane maintenance
Alfaxalone 2 mg/kg IV bolus followed by sevoflurane maintenance
Ketamine 5 mg/kg IV with diazepam 0.5 mg/kg IV combination
Etomidate 1–2 mg/kg IV with midazolam 0.2 mg/kg IV premedication (Correct answer)

Correct answer: Etomidate 1–2 mg/kg IV with midazolam 0.2 mg/kg IV premedication

Etomidate is the induction agent of choice in critically ill or cardiovascularly compromised patients because it produces minimal myocardial depression and maintains cardiac output and vascular tone better than propofol or alfaxalone. Midazolam co-induction reduces the etomidate dose needed and provides muscle relaxation without significant cardiovascular effects. Propofol and alfaxalone both cause dose-dependent vasodilation and myocardial depression. Ketamine, while a sympathomimetic, is contraindicated in patients with pre-existing tachyarrhythmias (common in Boxers with DCM) as it can exacerbate ventricular dysrhythmias.

Question 207: Which statement about the use of doxycycline in cats is most accurate?

Doxycycline is contraindicated in cats under 6 months due to bone growth plate damage
Subcutaneous injection of doxycycline is preferred over oral administration
Liquid or food must accompany doxycycline administration to prevent esophageal stricture (Correct answer)
Cats require twice the canine mg/kg dose due to faster hepatic clearance

Correct answer: Liquid or food must accompany doxycycline administration to prevent esophageal stricture

Doxycycline pills lodged in the feline esophagus cause chemical strictures; always follow tablets with food or water, or use liquid formulations.

Question 208: A USDA veterinarian performing post-mortem inspection on a steer carcass finds multiple, well-demarcated, caseous abscesses in the lungs and associated mediastinal lymph nodes. What is the correct disposition for this carcass?

Condemn the entire carcass. (Correct answer)
Pass for cooking only.
Condemn the thoracic organs and pass the rest of the carcass.
Pass for human consumption after trimming affected parts.

Correct answer: Condemn the entire carcass.

The lesions described (caseous necrosis/granulomas in lungs and associated lymph nodes) are classic for bovine tuberculosis (*Mycobacterium bovis*). According to USDA regulations, evidence of generalized tuberculosis, which includes extensive lesions in the thoracic cavity, requires condemnation of the entire carcass due to its significant zoonotic potential and systemic nature.

Question 209: A cat with confirmed hypertrophic cardiomyopathy (HCM) and left atrial enlargement (LA:Ao ratio 1.7) is asymptomatic and has no pleural effusion. Which of the following treatment decisions is BEST supported by current evidence-based feline cardiology guidelines?

Initiate furosemide prophylactically to prevent future congestive heart failure
Initiate atenolol to reduce dynamic left ventricular outflow tract obstruction and slow heart rate
Initiate clopidogrel to reduce the risk of arterial thromboembolism given the left atrial enlargement (Correct answer)
Initiate an ACE inhibitor to reduce left ventricular hypertrophy and remodeling

Correct answer: Initiate clopidogrel to reduce the risk of arterial thromboembolism given the left atrial enlargement

The FATCAT study and current consensus guidelines recommend clopidogrel over aspirin for cats with HCM and left atrial enlargement, as LA enlargement is the strongest predictor of arterial thromboembolism (ATE) risk in cats. Clopidogrel significantly reduces recurrence of ATE in cats that have experienced a prior event, and is widely extrapolated for primary prevention in high-risk cats with marked LA dilation. Atenolol may be used for dynamic LVOTO but is not universally indicated for all HCM cats. Furosemide is reserved for overt CHF. ACE inhibitors have not been shown to benefit pre-clinical HCM cats in controlled feline studies.

Question 210: A herd of 120 commercial beef cows has a pregnancy rate of 78% after a 63-day breeding season using natural service at a 1:25 bull-to-cow ratio. Breeding soundness evaluations (BSE) were performed on all bulls 45 days before turnout and all passed. Cow body condition averaged 5.5/9 at breeding. Progesterone assays on 20 randomly selected non-pregnant cows at preg-check reveal 14 of 20 have luteal-phase progesterone levels (>1 ng/mL). What is the MOST likely diagnosis for the reproductive failure in these cows?

Embryonic loss between days 16–45 of gestation after normal conception (Correct answer)
Subclinical BVDV infection causing early embryonic death after fertilization
Inadequate bull power with libido or musculoskeletal limitations undetected by BSE
Repeat breeding syndrome secondary to uterine subclinical endometritis from prior calving

Correct answer: Embryonic loss between days 16–45 of gestation after normal conception

The key finding is that 14/20 non-pregnant cows (70%) have luteal-phase progesterone at preg-check, indicating they were cycling and had been bred (they are in a luteal phase cycle, not anestrus), yet failed to maintain pregnancy. BSE-passed bulls in adequate numbers with cycling cows of good BCS points toward the problem occurring AFTER fertilization — early embryonic or fetal loss between days 16–45, after maternal recognition of pregnancy would have been expected but before the conceptus reached a size detectable at preg-check. BVDV is plausible but would require more evidence. Subclinical endometritis could cause repeat breeding but would more typically present with cows that cycle back quickly without sustained luteal activity. The high proportion with active corpora lutea suggests conception occurred but embryos were lost before or around preg-check, and they've cycled back.

Question 211: What is the primary concern when using ketamine as the sole anesthetic in a dog?

Prolonged recovery
Profound hypotension
Inadequate muscle relaxation and increased muscle tone (Correct answer)
Severe respiratory depression

Correct answer: Inadequate muscle relaxation and increased muscle tone

Ketamine alone causes increased muscle tone and catalepsy rather than muscle relaxation, so it is typically combined with a benzodiazepine or alpha-2 agonist for adequate relaxation.

Question 212: A rabbit is brought in with GI stasis. Which analgesic is safest to use in rabbits?

Aspirin
Meloxicam (Correct answer)
Acetaminophen
Ibuprofen

Correct answer: Meloxicam

Meloxicam is the preferred NSAID in rabbits and is commonly used for pain management due to its established safety profile in this species.

Question 213: Which parameter is most commonly monitored as a critical control point (CCP) during pasteurization of milk?

pH of the final product
Coliform count before processing
Time and temperature of heat treatment (Correct answer)
Fat content percentage

Correct answer: Time and temperature of heat treatment

Time and temperature are the critical control point parameters for pasteurization, as they determine whether pathogens are eliminated.

Question 214: Which antifungal drug works by inhibiting the enzyme lanosterol 14-alpha-demethylase, disrupting ergosterol synthesis?

Fluconazole (Correct answer)
Nystatin
Amphotericin B
Griseofulvin

Correct answer: Fluconazole

Fluconazole (and other azole antifungals) inhibit lanosterol 14-alpha-demethylase, blocking ergosterol synthesis and disrupting fungal cell membrane integrity.

Question 215: On a 500-cow dairy, the conception rate to first service drops from 42% to 28% over 3 months. Which herd-level factor should be investigated first?

Heat detection efficiency and estrus expression (Correct answer)
Bull fertility in the herd sire
BVD vaccination status of heifers only
Milk production records from 6 months ago

Correct answer: Heat detection efficiency and estrus expression

In AI-based dairies, poor heat detection is the most common cause of declining first-service conception rates, as undetected or wrongly timed AI submissions drive down the metric.

Question 216: A llama is treated with flunixin meglumine IV at the bovine label dose for 5 consecutive days for GI pain. Which adverse effect is MOST likely due to the species-specific pharmacokinetic difference compared to cattle?

Nephrotoxicity worsened by the llama's slower drug elimination half-life (Correct answer)
Hepatotoxicity from cytochrome P450 accumulation
Right dorsal colitis from prolonged COX-1 inhibition in the hindgut
Bone marrow suppression from camelid sensitivity to NSAIDs

Correct answer: Nephrotoxicity worsened by the llama's slower drug elimination half-life

Camelids (llamas, alpacas) have a significantly longer elimination half-life for flunixin meglumine (~10-12 hours) compared to cattle (~3-4 hours). Using the bovine dose and frequency leads to drug accumulation in camelids, with renal papillary necrosis and nephrotoxicity being the primary concern due to sustained COX-1 inhibition reducing renal prostaglandin synthesis. Right dorsal colitis is classically associated with horses on prolonged NSAIDs, not camelids.

Question 217: A bird (psittacine) presents with a bacterial infection. Which antibiotic class should be avoided due to risk of fatal dysbiosis?

Beta-lactams
Lincosamides and macrolides at high doses (Correct answer)
Aminoglycosides
Fluoroquinolones

Correct answer: Lincosamides and macrolides at high doses

Lincosamides (e.g., clindamycin) and certain macrolides can cause fatal disruption of the GI microbiome in birds, similar to the antibiotic-associated enterocolitis seen in other species.

Question 218: Nuclear scintigraphy (bone scan) in equine lameness is particularly valuable for identifying:

Nerve compression along the digital sheath
Soft tissue injuries with low bone involvement
Areas of increased bone remodeling before radiographic changes appear (Correct answer)
Joint effusion and synovial inflammation

Correct answer: Areas of increased bone remodeling before radiographic changes appear

Bone scintigraphy detects areas of increased osteoblastic activity and bone remodeling that may precede visible radiographic changes, making it useful for early stress fractures and occult bone pain.

Question 219: A dog receives an overdose of acepromazine. Which statement about acepromazine reversal is correct?

There is no specific reversal agent; treatment is supportive (Correct answer)
Reversal can be achieved with atipamezole
Naloxone effectively reverses acepromazine sedation
Flumazenil fully reverses phenothiazine effects

Correct answer: There is no specific reversal agent; treatment is supportive

Acepromazine, a phenothiazine tranquilizer, has no specific reversal agent; management consists of supportive care including IV fluids and vasopressors for hypotension.

Question 220: Acetaminophen (paracetamol) toxicity in cats primarily causes which two clinical findings?

Methemoglobinemia and hepatic necrosis (Correct answer)
Hypocalcemia and seizures
Acute renal failure and hypertension
Coagulopathy and thrombocytopenia

Correct answer: Methemoglobinemia and hepatic necrosis

Cats lack sufficient glucuronyl transferase to conjugate acetaminophen, leading to methemoglobinemia (muddy mucous membranes) and hepatic necrosis.

Question 221: A 9-year-old male neutered Golden Retriever presents with progressive forelimb lameness. Radiographs of the shoulder reveal a 'moth-eaten' lytic lesion of the proximal humerus with periosteal reaction and cortical destruction. What is the most likely diagnosis and treatment?

Hypertrophic osteodystrophy; supportive care
Osteochondrosis dissecans; arthroscopic debridement
Septic osteomyelitis; long-term antibiotics
Osteosarcoma; limb amputation with adjuvant carboplatin chemotherapy (Correct answer)

Correct answer: Osteosarcoma; limb amputation with adjuvant carboplatin chemotherapy

Osteosarcoma most commonly affects the proximal humerus in large breeds; amputation combined with carboplatin or doxorubicin chemotherapy provides the best median survival.

Question 222: A 7-year-old male castrated Persian cat presents with episodic vomiting, weight loss, and small-intestinal diarrhea. Jejunal biopsy reveals lymphocytic-plasmacytic infiltration with villous blunting. Serum folate is elevated and cobalamin is severely low. Which statement best explains the cobalamin deficiency in this patient?

Hepatic failure impairing cobalamin storage and enterohepatic recirculation
Cobalamin malabsorption due to loss of ileal cubilin/amnionless receptors from mucosal disease (Correct answer)
Exocrine pancreatic insufficiency causing absent intrinsic factor production
Bacterial overgrowth consuming cobalamin before ileal absorption can occur

Correct answer: Cobalamin malabsorption due to loss of ileal cubilin/amnionless receptors from mucosal disease

In cats, intrinsic factor is produced by the pancreas but cobalamin absorption occurs via cubilin/amnionless receptor complexes in the ileum. Diffuse small intestinal mucosal disease (as seen here with IBD/lymphoma) damages ileal absorptive receptors, causing cobalamin malabsorption despite normal pancreatic IF production. Elevated folate suggests proximal small intestinal bacterial overgrowth or intact proximal mucosa with bacteria producing folate. EPI would cause both low folate and low cobalamin. Severe ileal mucosal loss is the direct mechanism here.

Question 223: A dairy herd has a high prevalence of digital dermatitis (Mortellaro's disease). Which treatment is most effective for active, painful lesions?

Hoof trimming and copper sulfate footbath only
Surgical debridement under general anesthesia
Topical oxytetracycline applied to the lesion and wrapped with a bandage (Correct answer)
Systemic oxytetracycline injection

Correct answer: Topical oxytetracycline applied to the lesion and wrapped with a bandage

Topical oxytetracycline or lincomycin applied directly to digital dermatitis lesions after cleaning and drying, covered with a bandage, achieves the highest cure rates for active M2 lesions.

Question 224: During evaluation of a 9-year-old Andalusian with chronic bilateral forelimb lameness, distal limb flexion tests are strongly positive. MRI of the foot reveals a core lesion of the deep digital flexor tendon (DDFT) within the navicular bursa. Intra-bursal analgesia eliminates 90% of lameness bilaterally. Conservative management has failed after 8 months. Which surgical option directly addresses the pathological tension on the DDFT core lesion while preserving limb function?

Coffin joint arthrodesis
Navicular suspensory ligament desmotomy via a palmar approach
Palmar digital neurectomy at the level of the proximal sesamoid bones
Inferior check ligament desmotomy (accessory ligament of the DDFT) (Correct answer)

Correct answer: Inferior check ligament desmotomy (accessory ligament of the DDFT)

Inferior check ligament (accessory ligament of the DDFT) desmotomy reduces tension on the DDFT by eliminating the static tethering effect of the accessory ligament, allowing the DDFT to bear reduced load and facilitating healing of the core lesion. It is the preferred surgical option when MRI confirms DDFT pathology within the navicular bursa. Palmar digital neurectomy provides analgesia but does not address the biomechanical cause and carries risks of catastrophic tendon rupture.

Question 225: A cat with confirmed FeLV infection is most likely to develop which neoplastic condition?

Hepatocellular carcinoma
Mast cell tumor
Multicentric lymphoma (Correct answer)
Mammary adenocarcinoma

Correct answer: Multicentric lymphoma

FeLV strongly predisposes cats to multicentric lymphoma, particularly T-cell lymphoma in young cats.

Question 226: A hedgehog presents with a 2 cm cutaneous mass on the flank. Cytology shows round cells with a magenta granular cytoplasm. The most likely diagnosis is:

Mast cell tumor (Correct answer)
Fibrosarcoma
Squamous cell carcinoma
Lymphoma

Correct answer: Mast cell tumor

Mast cell tumors in hedgehogs show characteristic metachromatic (magenta) cytoplasmic granules on Romanowsky-stained cytology.

Question 227: A horse undergoes exploratory laparotomy for small intestinal volvulus. After 3 hours of surgery, the horse develops tachycardia, hypotension, and pale mucous membranes. Lactate is 12 mmol/L. What does this lactate value primarily indicate?

Hepatic failure from anesthetic agents
Severe tissue hypoperfusion and anaerobic metabolism (Correct answer)
Excessive intraoperative fluids causing hemodilution
Normal response to surgical stress

Correct answer: Severe tissue hypoperfusion and anaerobic metabolism

A lactate of 12 mmol/L indicates severe systemic hypoperfusion with anaerobic metabolism, which is a poor prognostic indicator in equine colic surgery.

Question 228: On a ventrodorsal thoracic radiograph, the cardiac silhouette of a healthy dog should not exceed what percentage of the thoracic width at the level of the 8th rib?

50%
70%
60% (Correct answer)
75%

Correct answer: 60%

The cardiac silhouette on a VD projection normally occupies no more than 60% of the thoracic width at the level of the 8th intercostal space.

Question 229: On a thoracic radiograph of a 10-year-old DSH cat, you identify a soft-tissue opacity in the caudodorsal lung field that effaces the descending aorta but preserves the diaphragmatic silhouette. The lesion has a sharp ventral border and an indistinct dorsal border. Which anatomic compartment and silhouette sign interpretation is correct?

Pleural effusion in the caudodorsal costophrenic recess; the indistinct dorsal border reflects fluid-air interface
Middle mediastinal mass; loss of cardiac silhouette confirms mediastinal origin
Diaphragmatic hernia; the preserved diaphragmatic line rules out rupture but the aortic effacement confirms herniated content
Caudodorsal pulmonary mass in the caudal lung lobe; positive silhouette sign with the aorta indicates the lesion is in contact with the aorta or the periaortic space (Correct answer)

Correct answer: Caudodorsal pulmonary mass in the caudal lung lobe; positive silhouette sign with the aorta indicates the lesion is in contact with the aorta or the periaortic space

A positive silhouette sign occurs when two structures of the same opacity (soft tissue) are in contact, causing their borders to be indistinguishable. Loss of the aortic silhouette indicates the caudodorsal lung lesion is in anatomic contact with the aorta or periaortic mediastinum — this localizes the mass to the caudal lobe or posterior mediastinum. The preserved diaphragmatic line rules out diaphragmatic hernia. Pleural effusion would cause a diffuse gravity-dependent opacity, not a discrete mass with a sharp ventral border. This pattern is classic for a primary lung tumor (e.g., adenocarcinoma) in the caudal lung lobe abutting the mediastinum.

Question 230: During a herd health visit to a 600-cow feedlot, you identify a pen of 150 steers (day 14 on feed) with a 9% morbidity rate. Pulled animals show biphasic fever, nasal discharge, and decreased rumination. At necropsy of a non-responder, you find cranioventral pulmonary consolidation, fibrinous pleuritis, and isolation of Mannheimia haemolytica serotype 1. The owner's current protocol uses metaphylaxis with tulathromycin on arrival. Which finding is MOST consistent with a failure of metaphylactic protocol rather than a true treatment failure?

M. haemolytica serotype 1 is intrinsically resistant to tulathromycin, indicating a wrong drug selection
The majority of morbidity cases are occurring between days 10–21 post-arrival, suggesting the 96-hour effective plasma concentration window of tulathromycin was exceeded before challenge (Correct answer)
A 9% morbidity rate is within acceptable limits for a high-risk pen and does not indicate protocol failure
Fibrinous pleuritis indicates a chronic infection predating arrival that metaphylaxis cannot address

Correct answer: The majority of morbidity cases are occurring between days 10–21 post-arrival, suggesting the 96-hour effective plasma concentration window of tulathromycin was exceeded before challenge

Tulathromycin achieves concentrations above the MIC for M. haemolytica in lung tissue for approximately 96 hours (4 days) post-injection, though tissue concentrations remain elevated longer. However, protection against clinical BRD is generally considered most effective for the first 10–14 days post-treatment. Morbidity clustering at days 10–21 indicates the window of metaphylactic protection has passed before the peak of viral/bacterial challenge — a pharmacokinetic/epidemiological timing mismatch. M. haemolytica serotype 1 retains susceptibility to macrolides including tulathromycin in most North American feedlot populations. Fibrinous pleuritis in a necropsy animal likely reflects disease progression in that individual, not herd-wide chronicity. A 9% rate in a high-risk pen is above acceptable thresholds (typically <5–8% depending on risk classification).

Question 231: During dynamic evaluation of a horse on a lunge circle, the examiner notices that forelimb lameness is most pronounced on the OUTSIDE limb when tracking left on a firm surface, but this pattern reverses on soft footing. Which pathological process is most consistent with this footing-dependent reversal?

Proximal suspensory desmitis with axial fiber involvement
Distal sesamoidean impar ligament desmopathy
Solar bruising of the lateral heel
Medial collateral ligament desmitis of the coffin joint (Correct answer)

Correct answer: Medial collateral ligament desmitis of the coffin joint

Collateral ligament desmitis of the distal interphalangeal (coffin) joint produces mediolateral loading-dependent lameness. On firm footing, the inside limb bears greater concussive medial load, but on the outside limb the lateral collateral structure is loaded via centrifugal ground reaction force. Soft footing attenuates peak impact loading and shifts the dominant force vector, reversing which limb appears lame. MRI is the gold standard for confirming collateral ligament lesions that are often missed on radiographs.

Question 232: You are managing a cat that ingested topical permethrin flea spray (concentrated dog formulation) 90 minutes ago. The cat is tremoring severely. After decontamination with dish soap, which treatment combination is MOST appropriate for controlling permethrin-induced tremors in this cat?

Atropine IV to block muscarinic hyperstimulation, followed by pralidoxime
Cyproheptadine PO or per rectum combined with methocarbamol IV
Lipid emulsion therapy (ILE) as sole treatment, given permethrin's high lipophilicity
Methocarbamol IV combined with diazepam; avoid pyrethroid-specific antidotes (Correct answer)

Correct answer: Methocarbamol IV combined with diazepam; avoid pyrethroid-specific antidotes

Permethrin toxicosis in cats causes sodium channel dysfunction leading to repetitive neuronal firing, manifesting as tremors and seizures. The treatment of choice for tremor control is methocarbamol (a muscle relaxant; 44–220 mg/kg IV slowly to effect) combined with diazepam or other benzodiazepines for CNS sedation and seizure control. There is no specific antidote. Atropine + pralidoxime is the antidote regimen for organophosphate/carbamate toxicity (which acts via AChE inhibition), not pyrethroids. Cyproheptadine (a serotonin antagonist) is used for serotonin syndrome, not permethrin toxicosis. IVLipid emulsion can be a useful adjunct in severe refractory cases but is not the primary or sole treatment.

Question 233: A 7-year-old spayed female cat is diagnosed with intermediate-grade small cell lymphoma of the GI tract confirmed via full-thickness biopsy showing transmural infiltration with loss of normal architecture. Which chemotherapy protocol is MOST appropriate compared to the standard low-grade (small cell) lymphoma protocol?

Toceranib phosphate targeting c-Kit mutation
Single-agent lomustine (CCNU)
Chlorambucil and prednisolone (COP equivalent)
CHOP-based protocol (cyclophosphamide, doxorubicin, vincristine, prednisolone) (Correct answer)

Correct answer: CHOP-based protocol (cyclophosphamide, doxorubicin, vincristine, prednisolone)

Intermediate- to high-grade feline GI lymphoma (large cell lymphoma) carries a significantly worse prognosis than the indolent small cell (low-grade) form and requires a more aggressive CHOP-based multi-agent protocol. The chlorambucil/prednisolone protocol used for small cell lymphoma is insufficient for large or intermediate cell disease. Single-agent lomustine has activity in some lymphomas but is not the standard of care here. Toceranib targets receptor tyrosine kinases and is not the treatment of choice for GI lymphoma.

Question 234: During exploratory laparotomy on a 4-year-old Border Collie for suspected intestinal foreign body, you discover a 6 cm segment of jejunum that is dark purple-black, lacks peristalsis, and does not bleed when cut. The mesenteric vessels to this segment appear grossly intact. You resect the segment. Intraoperatively, which suture pattern for the jejunojejunostomy anastomosis has been shown to produce the LEAST luminal narrowing in small-diameter bowel?

Single-layer continuous Gambee pattern
Single-layer simple interrupted appositional pattern (Correct answer)
Single-layer inverting Connell pattern
Two-layer inverting pattern using Cushing followed by Lembert

Correct answer: Single-layer simple interrupted appositional pattern

Single-layer simple interrupted appositional (end-to-end) anastomosis produces the least luminal narrowing because it avoids the inversion of tissue that inherently reduces the anastomotic diameter. Two-layer inverting patterns and continuous inverting patterns (Connell) reduce lumen diameter by folding tissue inward, which is particularly problematic in the small-bore jejunum of dogs. The Gambee pattern is a modified appositional pattern that also reduces inversion, but simple interrupted appositional remains the gold standard for minimizing stricture in veterinary small intestinal surgery. Healing strength and leak rates are comparable or superior for single-layer appositional techniques.

Question 235: Ringworm in cats is most commonly caused by which dermatophyte species?

Trichophyton verrucosum
Microsporum canis (Correct answer)
Epidermophyton floccosum
Microsporum gypseum

Correct answer: Microsporum canis

Microsporum canis accounts for approximately 90% of feline dermatophytosis cases and is also the predominant zoonotic species from cats.

Question 236: A 9-year-old Labrador Retriever is diagnosed with stage 3 chronic kidney disease (IRIS). Serum phosphorus is 6.8 mg/dL. Which intervention is most important to slow CKD progression?

IV fluid diuresis three times weekly
Increased protein supplementation
Phosphate restriction and phosphate binders (Correct answer)
Sodium restriction alone

Correct answer: Phosphate restriction and phosphate binders

Phosphate restriction through diet and phosphate binders reduces renal mineralization and is one of the most evidence-based strategies to slow CKD progression.

Question 237: A cat presents with acute rodenticide toxicosis from ingestion of brodifacoum. Vitamin K1 therapy is initiated. Which statement best describes the pharmacodynamic basis for why high doses and prolonged treatment (3–6 weeks) are required compared to warfarin toxicosis?

Brodifacoum undergoes extensive enterohepatic recirculation, maintaining toxic tissue concentrations long after ingestion (Correct answer)
Brodifacoum has a much shorter half-life than warfarin, requiring more frequent dosing
Brodifacoum depletes stores of vitamins K2 and K3, which cannot be replaced by K1 supplementation alone
Brodifacoum irreversibly alkylates the vitamin K epoxide reductase enzyme complex

Correct answer: Brodifacoum undergoes extensive enterohepatic recirculation, maintaining toxic tissue concentrations long after ingestion

Brodifacoum is a long-acting anticoagulant rodenticide with extensive enterohepatic recirculation and high lipophilicity, resulting in a plasma half-life of weeks to months in companion animals. This prolonged tissue retention means that even after a single ingestion, the drug continues to inhibit vitamin K epoxide reductase for an extended period. Treatment with vitamin K1 must continue until all brodifacoum is eliminated, typically 3–6 weeks, verified by PT/aPTT testing 48–72 hours after cessation.

Question 238: A 6-year-old horse is presented with a history of spontaneous, severe epistaxis (nosebleed) from the right nostril. Endoscopic examination reveals a large, diphtheritic membrane on the dorsal aspect of the right guttural pouch, overlying the internal carotid artery. What is the most definitive treatment to prevent a fatal hemorrhage in this horse?

Daily lavage of the guttural pouch with povidone-iodine
Long-term systemic antifungal therapy
Surgical removal of the fungal plaque
Transarterial coil embolization of the affected artery (Correct answer)

Correct answer: Transarterial coil embolization of the affected artery

Guttural pouch mycosis with erosion of a major artery, such as the internal carotid, is a life-threatening emergency due to the risk of fatal hemorrhage. The most effective and definitive treatment to prevent bleeding is to occlude blood flow to the affected arterial segment. Transarterial coil embolization is the preferred method to achieve this. While medical management with antifungal drugs is part of the overall treatment to resolve the infection, it does not address the immediate risk of catastrophic bleeding.

Question 239: A cat presents with acute onset of severe muscle tremors, hyperthermia, and mydriasis after the owner applied a canine-specific flea and tick spot-on product. Which of the following toxicities is most likely, and what is the primary therapeutic agent used to control the tremors?

Ethylene glycol toxicity; Fomepizole
Organophosphate toxicity; Atropine
Permethrin toxicity; Methocarbamol (Correct answer)
Ivermectin toxicity; Intralipid emulsion

Correct answer: Permethrin toxicity; Methocarbamol

The clinical signs described are classic for permethrin toxicity, which occurs when concentrated canine flea products containing this pyrethroid are applied to cats. Cats are deficient in the enzymes needed to metabolize permethrin effectively. The primary treatment for the resulting muscle tremors and fasciculations is the centrally-acting muscle relaxant, methocarbamol. Atropine is for organophosphate toxicity, fomepizole for ethylene glycol, and intralipid emulsion is an adjunctive therapy for lipid-soluble toxins like ivermectin.

Question 240: A 7-year-old German Shepherd presents with progressive rear limb ataxia. Spinal MRI reveals a well-defined, intradural extramedullary lesion at T10-T11 that is isointense on T1, hyperintense on T2, and demonstrates marked homogeneous contrast enhancement. The adjacent cord shows a 'cap sign' (hemosiderin deposition). Which diagnosis is MOST consistent with these findings?

Nephroblastoma (spinal)
Arachnoid diverticulum
Meningioma (Correct answer)
Peripheral nerve sheath tumor

Correct answer: Meningioma

Meningiomas are the most common intradural extramedullary spinal tumors in dogs, typically appearing isointense on T1, hyperintense on T2, with intense homogeneous contrast enhancement. The 'cap sign'—hemosiderin staining at the poles of the mass—is a specific MRI feature strongly associated with spinal meningiomas due to chronic microhemorrhage. Nephroblastomas occur in young dogs and are typically intramedullary. Peripheral nerve sheath tumors tend to extend through neural foramina. Arachnoid diverticula do not enhance with contrast.

Question 241: A cat with a suspected portosystemic shunt has an ammonia tolerance test performed. Which additional diagnostic best confirms intrahepatic vs. extrahepatic shunt location?

Abdominal ultrasound with Doppler
Rectal portal scintigraphy
CT angiography (Correct answer)
Serum bile acid pre/post prandial

Correct answer: CT angiography

CT angiography (computed tomographic angiography) provides precise anatomic delineation of shunt location and morphology, guiding surgical planning.

Question 242: A dog is presented with acute onset of non-ambulatory tetraparesis following a traumatic event. Spinal radiographs reveal atlantoaxial subluxation. What is the definitive treatment of choice?

Cervical splinting with a neck brace
Strict cage rest alone
Corticosteroid therapy
Surgical stabilization of the atlantoaxial joint (Correct answer)

Correct answer: Surgical stabilization of the atlantoaxial joint

Surgical stabilization via ventral fixation or dorsal wiring provides definitive correction of atlantoaxial subluxation, which otherwise risks life-threatening spinal cord compression.

Question 243: A 12-year-old cat with known hyperthyroidism controlled on methimazole develops acute azotemia (creatinine 3.8 mg/dL, BUN 58 mg/dL) after 3 weeks of therapy. Pre-treatment creatinine was 1.1 mg/dL. Which pathophysiologic explanation is most accurate?

Unmasking of pre-existing chronic kidney disease as GFR normalizes with euthyroid state (Correct answer)
Methimazole-induced immune-mediated glomerulonephritis
Hypertensive nephrosclerosis worsening as cardiac output drops with treatment
Direct tubular toxicity from methimazole metabolites accumulating in renal cortex

Correct answer: Unmasking of pre-existing chronic kidney disease as GFR normalizes with euthyroid state

Hyperthyroidism increases cardiac output and causes hyperfiltration, artificially elevating GFR and suppressing serum creatinine. When hyperthyroidism is treated and GFR normalizes, underlying CKD that was masked by the hyperfiltration state becomes apparent. This 'unmasking' phenomenon is well-documented in feline medicine and is why pre-treatment renal biomarkers can be misleadingly normal. The pre-treatment creatinine of 1.1 mg/dL was falsely low due to increased GFR, not because the kidneys were truly healthy.

Question 244: Which method is used to calculate the attack rate during a foodborne illness outbreak investigation?

Number ill / total population × 100
Number ill / number exposed × 100 (Correct answer)
Number exposed / number ill × 100
Number new cases / population at risk × 100

Correct answer: Number ill / number exposed × 100

Attack rate = (number of ill persons / number exposed) × 100, measuring the proportion of exposed individuals who became ill.

Question 245: A 2-year-old bearded dragon (Pogona vitticeps) is presented with open-mouth breathing, neck extension, and mucus accumulation in the glottis. Radiographs show increased pulmonary opacity in the caudal lung fields. A tracheal wash reveals Gram-negative rods, and the owner reports the animal is maintained at 85°F ambient temperature with a basking spot of 95°F. Which factor is MOST directly contributing to immunosuppression in this patient?

Excessive humidity above 40% promoting bacterial overgrowth in the respiratory tract
Suboptimal thermal environment reducing enzymatic activity of immune effector cells (Correct answer)
High-protein diet causing hepatic stress and reduced acute-phase protein synthesis
Inadequate photoperiod causing melatonin-mediated thymic involution

Correct answer: Suboptimal thermal environment reducing enzymatic activity of immune effector cells

Reptiles are ectotherms whose immune function is temperature-dependent. Bearded dragons require a thermal gradient of 80–85°F ambient with a basking spot of 100–110°F. A basking spot of only 95°F is suboptimal. Immune cell enzymatic activity, phagocyte function, lymphocyte proliferation, and complement activity all depend on achieving the Preferred Optimal Temperature Zone (POTZ). An inadequate thermal gradient directly impairs the immune response, allowing opportunistic Gram-negative bacteria (commonly Aeromonas, Pseudomonas, or Enterobacteriaceae) to cause respiratory infection. Correcting husbandry is as therapeutically important as antibiotic therapy.

Question 246: A dog is diagnosed with leptospirosis after exposure to wildlife. Which organ system is MOST commonly affected, leading to the clinical presentation seen in acute leptospirosis?

Central nervous system
Renal and hepatic systems (Correct answer)
Respiratory system primarily
Musculoskeletal system

Correct answer: Renal and hepatic systems

Leptospira organisms have a particular tropism for renal tubular epithelium and hepatocytes, leading to acute kidney injury and hepatopathy as the dominant clinical syndrome.

Question 247: A green iguana is presented for severe metabolic bone disease refractory to standard calcium and UVB supplementation. Bloodwork shows hypocalcemia, hyperphosphatemia, and markedly elevated PTH. Renal function tests reveal azotemia. Which pathophysiologic mechanism BEST explains this presentation?

Vitamin D3 toxicosis causing soft-tissue mineralization and paradoxical hypocalcemia
Renal secondary hyperparathyroidism caused by impaired 1-alpha-hydroxylation of 25-hydroxyvitamin D3 and phosphate retention (Correct answer)
Nutritional secondary hyperparathyroidism due to dietary calcium-to-phosphorus imbalance below 1:1
Primary hypoparathyroidism with compensatory skeletal calcium mobilization

Correct answer: Renal secondary hyperparathyroidism caused by impaired 1-alpha-hydroxylation of 25-hydroxyvitamin D3 and phosphate retention

This iguana has renal secondary hyperparathyroidism. Azotemia indicates renal disease, which impairs 1-alpha-hydroxylation of 25-hydroxyvitamin D3 in the kidneys, reducing calcitriol production. Reduced calcitriol impairs intestinal calcium absorption, and phosphate retention by the failing kidneys further drives hypocalcemia. The resulting PTH elevation mobilizes bone, leading to metabolic bone disease. This is distinct from nutritional secondary hyperparathyroidism, which occurs without azotemia.

Question 248: On a lateral skull radiograph of a rabbit, you observe bilateral tympanic bullae with significantly increased opacity and thickened walls. The petrous temporal bones appear sclerotic. This pattern is MOST consistent with:

Thymoma with paraneoplastic vestibular syndrome
Otitis media/interna with secondary bulla osteitis (Correct answer)
Cervical lymphoma compressing the vestibulocochlear nerve
Encephalitozoon cuniculi granulomatous encephalitis

Correct answer: Otitis media/interna with secondary bulla osteitis

In rabbits, bilateral tympanic bulla opacification with wall thickening and petrous bone sclerosis on skull radiographs is diagnostic of chronic otitis media/interna with bulla osteitis. Pasteurella multocida is the most common causative agent. This imaging triad—bulla opacity, bulla wall thickening, and petrosal sclerosis—represents chronic inflammatory and reactive bone change. Encephalitozoon cuniculi causes neurological signs but does not produce radiographic bulla changes. Thymoma is a thoracic disease. Cervical lymphoma would not produce intraosseous bulla changes visible radiographically.

Question 249: A 2-year-old male intact German Shepherd presents with a 3-week history of mucopurulent nasal discharge unilateral to the left nostril, sneezing, and mild epistaxis. Rhinoscopy reveals a pale, irregular mucosal lesion. Biopsy shows pyogranulomatous inflammation with broad, pauciseptate hyphae with right-angle branching on GMS stain. Which organism is MOST likely responsible, and what is the MOST appropriate initial antifungal therapy?

Conidiobolus coronatus — itraconazole monotherapy (Correct answer)
Aspergillus fumigatus — topical clotrimazole infusion via trephination
Rhinosporidium seeberi — surgical debulking with no antifungal indicated
Pythium insidiosum — itraconazole + terbinafine combination

Correct answer: Conidiobolus coronatus — itraconazole monotherapy

Broad, pauciseptate hyphae with right-angle branching on GMS stain in a dog with nasal/facial disease is characteristic of zygomycetes, specifically the Entomophthoromycota order. Conidiobolus coronatus (formerly Entomophthora coronata) causes rhinofacial conidiobolomycosis — pyogranulomatous rhinitis with broad hyphae that are difficult to culture. Aspergillus produces narrower, septate hyphae with acute-angle branching. Pythium is an oomycete (not a true fungus) presenting as GI/subcutaneous disease, and its hyphae are similar but the clinical presentation differs. Rhinosporidium produces sporangia, not hyphae. Itraconazole is the recommended first-line treatment for Conidiobolus, though prognosis is guarded.

Question 250: A 7-year-old cat presents with a history of chronic vomiting, diarrhea, and weight loss. Bloodwork reveals a low serum cobalamin (Vitamin B12) level. Concurrent inflammation of the intestine, pancreas, and biliary tract is suspected. What is this condition called?

Lymphocytic-plasmacytic enteritis
Exocrine pancreatic insufficiency (EPI)
Feline Infectious Peritonitis (FIP)
Triaditis (Correct answer)

Correct answer: Triaditis

Feline triaditis is the concurrent inflammation of the pancreas (pancreatitis), biliary tract (cholangitis), and small intestine (inflammatory bowel disease). This combination of conditions is common in cats and often leads to malabsorption, resulting in clinical signs like vomiting, weight loss, and hypocobalaminemia due to impaired intestinal absorption. While the other conditions can cause similar signs, 'triaditis' specifically refers to the inflammation of these three associated organs.

Question 251: Propylene glycol is present in some semi-moist cat foods and medications. Why is it contraindicated in cats?

It is directly nephrotoxic through oxalate crystal deposition
It causes acute pancreatitis due to lipase inhibition
It causes hypernatremia by drawing water from red blood cells
It causes Heinz body formation and hemolytic anemia in cats (Correct answer)

Correct answer: It causes Heinz body formation and hemolytic anemia in cats

Cats are uniquely susceptible to propylene glycol-induced Heinz body hemolytic anemia because their hemoglobin contains eight SH groups versus four in dogs.

Question 252: A sugar glider presents with self-mutilation of the scrotum and hindquarters. The most common underlying cause is:

Ectoparasite infestation
Stress and/or inappropriate husbandry (Correct answer)
Fungal dermatitis
Nutritional secondary hyperparathyroidism

Correct answer: Stress and/or inappropriate husbandry

Self-mutilation in sugar gliders is most commonly associated with stress, social isolation, or inappropriate diet and environmental conditions.

Question 253: A 6-year-old DSH cat with hyperthyroidism is started on methimazole. Two weeks later, the owner reports the cat is scratching its face intensely and has developed facial excoriations. Which statement BEST explains the pathophysiology and recommended management?

Methimazole-induced hypothyroidism has unmasked latent feline hyperesthesia syndrome; adjust thyroid hormone levels with levothyroxine supplementation
Facial pruritus is a known idiosyncratic drug reaction in cats, likely immune-mediated; discontinue methimazole and consider carbimazole or alternative definitive therapy (Correct answer)
This represents a Type II hypersensitivity reaction to methimazole; switch to radioactive iodine (I-131) therapy
Methimazole causes dose-dependent peripheral neuropathy; reduce the dose by 50% and monitor for resolution

Correct answer: Facial pruritus is a known idiosyncratic drug reaction in cats, likely immune-mediated; discontinue methimazole and consider carbimazole or alternative definitive therapy

Facial pruritus and self-excoriation is a well-documented idiosyncratic adverse effect of methimazole in cats, occurring in approximately 2–3% of treated cats, typically within the first 1–3 months of therapy. The mechanism is thought to be immune-mediated. This reaction is an indication to discontinue methimazole immediately, as continued use can lead to more severe reactions including hepatotoxicity, thrombocytopenia, or agranulocytosis. Carbimazole (a prodrug of methimazole) should theoretically cross-react, so definitive therapy with I-131, surgical thyroidectomy, or a prescription iodine-restricted diet (Hill's y/d) is preferred. This is not a dose-dependent effect and dose reduction is inadequate management.

Question 254: A 7-year-old Thoroughbred mare undergoes emergency celiotomy for small colon impaction. The surgeon identifies a mesenteric rent through which small intestine has passed and become strangulated. After reducing the hernia and assessing the intestine, the surgeon should:

Leave the mesenteric rent open to prevent recurrence
Perform a bypass anastomosis without closing the rent
Close the mesenteric rent with simple interrupted sutures after intestinal assessment (Correct answer)
Pack the rent with omentum and close the abdomen

Correct answer: Close the mesenteric rent with simple interrupted sutures after intestinal assessment

Mesenteric rents must be closed after reducing the herniated intestine to prevent recurrence of internal herniation and strangulation.

Question 255: A 4-year-old spayed female cat with hypertrophic cardiomyopathy (HCM) requires anesthesia for a perineal urethrostomy. Which of the following induction protocols would be MOST appropriate to maintain cardiac output while avoiding tachycardia and excessive vasodilation?

Etomidate (1–2 mg/kg IV) + midazolam (0.2 mg/kg IV) (Correct answer)
Propofol (4 mg/kg IV) + fentanyl (2 mcg/kg IV)
Ketamine (5 mg/kg IM) + midazolam (0.2 mg/kg IM)
Alfaxalone (2 mg/kg IV) + butorphanol (0.2 mg/kg IV)

Correct answer: Etomidate (1–2 mg/kg IV) + midazolam (0.2 mg/kg IV)

Etomidate is the preferred induction agent in patients with compromised cardiac function because it provides the most cardiovascular stability of any injectable induction agent — minimal effects on heart rate, contractility, and systemic vascular resistance. Midazolam reduces the myoclonus associated with etomidate. Propofol causes vasodilation and can cause hypotension. Ketamine increases heart rate and sympathetic tone, which is detrimental in HCM where diastolic filling is already impaired. Alfaxalone, while moderate, has more hemodynamic effects than etomidate in cats with significant cardiac disease.

Question 256: During a herd health visit to a 300-cow cow-calf operation, you review the spring vaccination protocol. Calves receive modified-live virus (MLV) BVDV vaccine at branding (approximately 3 months of age). Several producers in the region report that calves vaccinated with MLV-BVDV at this age occasionally fail to seroconvert. Which mechanism BEST explains this vaccine failure in the context of herd health?

Colostral maternal antibody interference neutralizing vaccine virus before an immune response is mounted (Correct answer)
Concurrent PI (persistently infected) calves shedding wild-type BVDV that overcompetes with vaccine virus
BVDV Type 2 strains in the MLV vaccine are poorly immunogenic in calves under 6 months
CD8+ T-cell immaturity at 3 months of age prevents development of cytotoxic memory

Correct answer: Colostral maternal antibody interference neutralizing vaccine virus before an immune response is mounted

Maternal antibody interference is the classic and most well-documented explanation for MLV-BVDV vaccine failure at branding age. Calves acquire passive immunity through colostrum, and maternally derived antibodies (MDA) to BVDV can persist for 3–6 months or longer depending on colostrum quality and dam titer. These MDAs neutralize the attenuated vaccine virus before the calf's own immune system can mount a primary response, resulting in seronegative calves despite vaccination. This is why some protocols recommend delaying BVDV vaccination until weaning (~6–7 months) or using killed vaccine initially. PI calves shedding high-titer wild-type BVDV can cause immunotolerance in herd-mates but do not mechanistically interfere with vaccine virus the same way MDA does.

Question 257: Which drug is used to treat hyperthyroidism in cats by blocking thyroid hormone synthesis?

Methimazole (Correct answer)
Radioactive iodine (I-131)
Levothyroxine
Propranolol

Correct answer: Methimazole

Methimazole inhibits thyroid peroxidase, thereby blocking the synthesis of thyroid hormones and is the most common medical management for feline hyperthyroidism.

Question 258: Which of the following birds is most susceptible to aspergillosis due to its natural habitat and immune characteristics?

Gyrfalcon (Correct answer)
Cockatiel
African grey parrot
Budgerigar

Correct answer: Gyrfalcon

Gyrfalcons and other Arctic raptors lack prior environmental exposure to Aspergillus and are highly immunologically naive, making them very susceptible.

Question 259: A cat diagnosed with nasal lymphoma has disease confined to the nasal cavity. Which treatment modality offers the best local control and median survival?

Rhinotomy and debulking
Intranasal corticosteroids
Radiation therapy alone (Correct answer)
Systemic chemotherapy alone

Correct answer: Radiation therapy alone

Radiation therapy is the treatment of choice for nasal lymphoma in cats, providing excellent local control with median survival times of 18–24 months.

Question 260: You are investigating a cluster of sudden deaths in a cow-calf beef herd on lush spring pasture. Three 6-month-old calves died within 24 hours; post-mortem findings include bloat, hemorrhagic abomasitis, and a characteristic smell of recently mown grass from rumen contents. Clostridium septicum is isolated from the abomasal wall. What is the MOST likely predisposing factor that allowed this organism to become pathogenic?

Failure of passive transfer leading to hypogammaglobulinemia
Copper deficiency suppressing neutrophil function
Abomasal mucosal damage from rapid dietary change causing hemorrhagic abomasitis that created an anaerobic microenvironment (Correct answer)
Concurrent bovine viral diarrhea virus (BVDV) immunosuppression enabling clostridial overgrowth

Correct answer: Abomasal mucosal damage from rapid dietary change causing hemorrhagic abomasitis that created an anaerobic microenvironment

Braxy (caused by Clostridium septicum) classically occurs when sudden ingestion of large quantities of cold, lush, or frosted forage causes abomasal mucosal inflammation and focal necrosis. The resulting damaged, poorly perfused mucosa creates the anaerobic, protein-rich microenvironment that permits C. septicum spores (normally ingested without consequence) to germinate and proliferate. The toxins produced cause local and systemic disease. While copper deficiency (A) and BVDV (D) can cause immunosuppression, they are not the primary predisposing mechanism for braxy specifically. Failure of passive transfer (C) is relevant to neonatal septicemia, not braxy in 6-month-old calves.

Question 261: Which of the following is a primary therapeutic goal in the management of a dog with chronic kidney disease (CKD) and proteinuria?

Administering loop diuretics to increase GFR
Supplementing with high doses of Vitamin D to manage secondary hyperparathyroidism
Increasing dietary protein to counteract losses
Controlling systemic hypertension and reducing phosphorus intake (Correct answer)

Correct answer: Controlling systemic hypertension and reducing phosphorus intake

Management of canine CKD focuses on slowing disease progression and improving quality of life. Key goals include controlling systemic hypertension, which can exacerbate kidney damage, and reducing dietary phosphorus intake to manage renal secondary hyperparathyroidism. Protein restriction (not increase) is often indicated, and while diuretics have a role in specific situations, they don't increase GFR. Vitamin D supplementation must be done cautiously to avoid hypercalcemia.

Question 262: Which scoring system is validated for assessing acute pain in cats in the postoperative period?

Glasgow Composite Measure Pain Scale – Short Form (CMPS-SF)
Numeric Rating Scale (NRS) only
UNESP-Botucatu Multidimensional Composite Pain Scale
Colorado State University Feline Acute Pain Scale (Correct answer)

Correct answer: Colorado State University Feline Acute Pain Scale

The Colorado State University Feline Acute Pain Scale is a validated, species-specific tool widely used in clinical settings to assess acute pain in cats.

Question 263: Which antifungal drug is currently the first-line treatment for aspergillosis in birds?

Ketoconazole
Voriconazole (Correct answer)
Amphotericin B
Griseofulvin

Correct answer: Voriconazole

Voriconazole is the preferred antifungal for avian aspergillosis due to its superior efficacy and safety compared to older azoles.

Question 264: Bovine trichomoniasis (caused by Tritrichomonas foetus) is a venereal disease affecting beef cattle. Which control strategy is most effective in eliminating trichomoniasis from an infected beef herd?

Systemic metronidazole treatment of all infected bulls
Culling infected bulls and resting infected cows for 90+ days to allow self-clearance (Correct answer)
Vaccination of all cows with the T. foetus vaccine to prevent abortion
Antibiotic treatment of all cattle and 30-day quarantine

Correct answer: Culling infected bulls and resting infected cows for 90+ days to allow self-clearance

Bulls are permanent carriers and cannot be treated; culling PCR-positive bulls and resting exposed cows (which self-clear in approximately 90 days of sexual rest) is the standard eradication approach.

Question 265: Feline calicivirus virulent systemic strain (VS-FCV) outbreaks are characterized by which distinctive clinical sign NOT typical of classic FCV?

Oral ulceration
Sneezing
Subcutaneous edema and facial swelling (Correct answer)
Conjunctivitis

Correct answer: Subcutaneous edema and facial swelling

VS-FCV causes severe systemic disease including facial and limb edema, skin ulceration, and high mortality, distinguishing it from classical FCV.

Question 266: A 6-month-old female intact pig (Sus scrofa domesticus) raised as a pet presents with acute onset of paddling, opisthotonus, and salivation. The owner reports feeding table scraps including salted pork rinds and leftover soup. On exam the pig is non-febrile but disoriented. CSF tap shows increased protein with no organisms on Gram stain. Which diagnosis best explains this presentation?

Pseudorabies (Aujeszky's disease)
Mulberry heart disease (vitamin E/selenium deficiency)
Salt poisoning / water deprivation encephalopathy (Correct answer)
Streptococcus suis meningitis

Correct answer: Salt poisoning / water deprivation encephalopathy

Salt poisoning (sodium ion toxicosis) in pigs occurs classically when animals with water deprivation are suddenly allowed free water intake, OR when fed high-sodium diets without adequate water access. The CSF findings of elevated protein with no organisms, combined with the high-sodium diet history (salted pork rinds, soup), point strongly to this diagnosis. The classic histopathologic finding is eosinophilic meningoencephalitis with perivascular cuffing. Streptococcus suis would typically show CSF neutrophilia and organisms. Pseudorabies causes intense pruritus ('mad itch') and is reportable. Mulberry heart disease presents with sudden death, not CNS signs.

Question 267: A dog is receiving a fentanyl CRI at 5 mcg/kg/hr intraoperatively. Signs of opioid-induced bradycardia appear. Which drug reverses fentanyl's cardiovascular effects with the least effect on analgesia?

Naloxone full dose IV
Flumazenil IV
Atipamezole IV
Glycopyrrolate IV to treat bradycardia without reversing opioid (Correct answer)

Correct answer: Glycopyrrolate IV to treat bradycardia without reversing opioid

Glycopyrrolate treats opioid-induced bradycardia by blocking vagal tone without reversing analgesia, unlike naloxone which would eliminate pain control.

Question 268: A One Health investigation links a series of human Cryptosporidium parvum cases to a municipal watershed used for drinking water. Environmental sampling finds oocysts at 2.7 oocysts/10L in the raw water intake. The watershed is shared by a confined dairy operation upstream. Which characteristic of C. parvum oocysts most limits the effectiveness of standard municipal water chlorination as the sole treatment barrier?

Oocysts are larger than 1 µm and clog conventional slow-sand filters
C. parvum rapidly develops chlorine resistance through plasmid-mediated mechanisms after repeated exposure
Oocysts are effectively killed by chlorine only at pH < 5, which is incompatible with drinking water standards
The oocyst wall confers extraordinary chlorine resistance, requiring CT values far exceeding those achievable with standard disinfection doses (Correct answer)

Correct answer: The oocyst wall confers extraordinary chlorine resistance, requiring CT values far exceeding those achievable with standard disinfection doses

Cryptosporidium oocysts are highly resistant to chlorine disinfection due to their thick, proteinaceous oocyst wall. Achieving a 3-log (99.9%) reduction requires CT (concentration × time) values of >7,200 mg·min/L at 25°C — far beyond what is operationally feasible in municipal systems (typical CT for Giardia is ~55 mg·min/L). This is why the EPA Surface Water Treatment Rule requires filtration (which physically removes oocysts) rather than relying on chlorination alone. C. parvum does not acquire chlorine resistance through plasmid-mediated mechanisms (it is a protozoan, not a bacterium), and the pH sensitivity described is incorrect — UV irradiation and filtration are the validated control strategies.

Question 269: A dairy herd manager asks about dry cow therapy. Which approach describes selective dry cow therapy (SDCT)?

Withholding all treatment during the dry period
Treating all cows with intramammary antibiotics at dry-off
Treating only cows with elevated SCC or positive culture at dry-off (Correct answer)
Treating only fresh cows showing clinical mastitis

Correct answer: Treating only cows with elevated SCC or positive culture at dry-off

Selective dry cow therapy targets only cows with evidence of intramammary infection, reducing antibiotic use compared to blanket dry cow therapy.

Question 270: Which opioid analgesic is commonly used in cats but must be used cautiously due to their limited glucuronidation capacity?

Buprenorphine (Correct answer)
Hydromorphone
Fentanyl
Morphine

Correct answer: Buprenorphine

Buprenorphine is preferred in cats because its partial agonist activity and high mu-receptor affinity make it effective at lower doses, reducing the risk of adverse effects from impaired glucuronidation.

Question 271: A 9-year-old dog with a meningioma is receiving mannitol (0.5 g/kg IV) preoperatively to reduce intracranial pressure (ICP). Which of the following anesthetic agents would be the MOST appropriate choice for induction to avoid exacerbating elevated ICP?

Propofol (4 mg/kg IV, titrated slowly) (Correct answer)
Ketamine (5 mg/kg IV)
Alfaxalone (3 mg/kg IV bolus)
Tiletamine-zolazepam (2 mg/kg IV)

Correct answer: Propofol (4 mg/kg IV, titrated slowly)

Propofol reduces cerebral metabolic rate of oxygen consumption (CMRO2), cerebral blood flow, and ICP, making it the preferred induction agent in patients with elevated ICP. It should be titrated slowly to avoid hypotension, which would reduce cerebral perfusion pressure. Ketamine and tiletamine-zolazepam are contraindicated in patients with elevated ICP because they increase cerebral blood flow and ICP. Alfaxalone at a large bolus dose can cause cardiovascular depression and, unlike propofol, does not have the same well-established cerebroprotective profile in this context.

Question 272: On ultrasound, a hypoechoic halo surrounding a hepatic mass in a dog is called:

Acoustic enhancement
Reverberation artifact
Comet tail artifact
Target lesion (Correct answer)

Correct answer: Target lesion

A hypoechoic halo surrounding a mass on ultrasound is referred to as a target or bull's-eye lesion, often associated with metastatic disease.

Question 273: What is the recommended colostrum management '1-2-3 rule' for newborn dairy calves?

2 liters within 1 hour, IgG ≥22 g/L confirmed by colostrometer
1 gallon within 2 hours of birth, immunoglobulin concentration ≥50 g/L (Brix ≥22%) (Correct answer)
1 pint within 3 hours, tested by refractometer at ≥30% Brix
3 feedings within the first day, 1 liter each time

Correct answer: 1 gallon within 2 hours of birth, immunoglobulin concentration ≥50 g/L (Brix ≥22%)

The 1-2-3 rule recommends 1 gallon (≈4 L) of high-quality colostrum (≥50 g/L IgG) fed within the first 2 hours after birth, with a Brix refractometer reading ≥22% confirming adequate quality.

Question 274: Which radiographic finding is MOST consistent with pyloric outflow obstruction in a dog?

Dilated small intestinal loops > 3x rib width
Retroperitoneal effusion with loss of serosal detail
Markedly distended stomach with delayed gastric emptying (Correct answer)
Free peritoneal gas on the VD view

Correct answer: Markedly distended stomach with delayed gastric emptying

Pyloric obstruction causes gastric outflow failure, producing marked gastric distension with delayed or absent contrast passage on fluoroscopy.

Question 275: A 6-year-old castrated male DSH is prescribed oral diazepam (1 mg PO BID) for urine marking behavior. On day 4, the owner reports acute lethargy, jaundice, and anorexia. ALT is 1,840 U/L and total bilirubin is 8.2 mg/dL. What is the most accurate characterization of this adverse reaction?

Type B hypersensitivity reaction triggered by benzodiazepine ring oxidation products in genetically susceptible cats
Cholestatic hepatopathy caused by benzodiazepine-induced bile duct compression in cats with subclinical biliary disease
Idiosyncratic acute hepatic necrosis unique to cats receiving oral benzodiazepines, unrelated to dose or duration (Correct answer)
Predictable accumulation of diazepam's active metabolite desmethyldiazepam due to impaired feline glucuronidation

Correct answer: Idiosyncratic acute hepatic necrosis unique to cats receiving oral benzodiazepines, unrelated to dose or duration

Oral diazepam causes idiosyncratic acute hepatic necrosis in cats — a reaction that is unpredictable, not dose-dependent, and appears to be specific to the oral route. Affected cats can deteriorate rapidly within 2–5 days of initiating therapy. The mechanism is not fully elucidated but is not simply pharmacokinetic accumulation. IV diazepam carries much lower risk. This is why oral diazepam is generally contraindicated in cats, with alternatives such as gabapentin or environmental modification preferred for behavioral indications.

Question 276: A cat ingests mouse bait containing brodifacoum. How long after ingestion can clinical signs of coagulopathy be expected?

12–24 hours
7–10 days
3–5 days (Correct answer)
Within 2 hours

Correct answer: 3–5 days

Brodifacoum depletes vitamin K-dependent clotting factors; signs appear after existing factors are consumed, typically 3–5 days post-ingestion.

Question 277: Which critical temperature range is considered the 'danger zone' for bacterial growth in potentially hazardous foods?

50°F to 165°F (10°C to 74°C)
32°F to 40°F (0°C to 4°C)
40°F to 140°F (4°C to 60°C) (Correct answer)
60°F to 180°F (16°C to 82°C)

Correct answer: 40°F to 140°F (4°C to 60°C)

The USDA defines the temperature danger zone as 40°F to 140°F (4°C to 60°C), where most foodborne pathogens multiply rapidly.

Question 278: A 400-head stocker operation is dealing with a multi-year history of bovine pinkeye (infectious bovine keratoconjunctivitis). Despite annual Moraxella bovis vaccination, prevalence remains above 15% during peak summer months. Molecular typing reveals the predominant circulating strain carries the pilQ gene variant not represented in the commercial vaccine. Beyond revised vaccine strategy, which additional herd management intervention has the strongest evidence base for reducing IBC transmission in this scenario?

Mass administration of tulathromycin at arrival to all stockers to eliminate pharyngeal Moraxella bovis carriage before fly season
Genetic selection for increased pigmentation around the periocular region to reduce UV-mediated mucosal susceptibility
Fly control targeting Musca autumnalis (face fly), combined with reducing ultraviolet light exposure through shade structures (Correct answer)
Topical ophthalmic administration of 1% oxytetracycline ointment to all cattle during high-risk periods as chemoprophylaxis

Correct answer: Fly control targeting Musca autumnalis (face fly), combined with reducing ultraviolet light exposure through shade structures

Musca autumnalis (the face fly) is the primary mechanical vector for Moraxella bovis, feeding on ocular secretions and transferring the bacteria between animals. Face fly control is one of the most evidence-supported non-vaccine interventions for reducing IBC incidence. Ultraviolet light is an established co-factor that damages the corneal epithelium and increases susceptibility; shade provision reduces UV exposure. Mass tulathromycin metaphylaxis (A) is not an evidence-based strategy for IBC prevention and raises significant stewardship concerns. Topical oxytetracycline chemoprophylaxis (C) is impractical at herd scale and not evidence-based for prevention. Periocular pigmentation (D) has a biological basis (Hereford breeds are more susceptible) but is not an actionable short-term herd intervention and lacks strong intervention trial evidence in this context.

Question 279: A 4-year-old Greyhound is prescribed phenobarbital for epilepsy. Compared to a Labrador Retriever of the same weight, which pharmacokinetic difference most significantly affects dosing in Greyhounds?

Greyhounds have reduced hepatic CYP450 enzyme activity, leading to slower phenobarbital clearance
Greyhounds have a lower volume of distribution for lipophilic drugs due to minimal body fat, resulting in higher plasma concentrations (Correct answer)
Greyhounds have accelerated renal tubular secretion of phenobarbital, requiring higher doses to maintain therapeutic levels
Greyhounds exhibit increased P-glycoprotein expression at the blood-brain barrier, reducing CNS penetration

Correct answer: Greyhounds have a lower volume of distribution for lipophilic drugs due to minimal body fat, resulting in higher plasma concentrations

Greyhounds have exceptionally low body fat (1–3% vs. 15–25% in mixed breeds). Phenobarbital is a lipophilic drug that distributes into adipose tissue. With minimal fat stores, the volume of distribution is reduced, leading to higher peak plasma concentrations at standard mg/kg doses. This means Greyhounds are at greater risk for toxicity and often require lower initial doses. Hepatic clearance differences exist for some drugs (e.g., propofol, thiopental) but are not the primary concern with phenobarbital dosing.

Question 280: A 3-year-old Standardbred trotter presents with acute non-weight-bearing left forelimb lameness after a race. Physical examination reveals marked swelling of the fetlock, severe pain on palpation of the medial aspect of the proximal sesamoid bones, and a dropped fetlock. Radiographs confirm a comminuted biaxial proximal sesamoid bone fracture. When assessing prognosis for athletic recovery (return to racing), which specific radiographic feature carries the WORST prognostic significance?

Presence of a single parasagittal fracture line through the apical one-third of both sesamoids
Fracture fragment displacement of less than 2 mm on the medial sesamoid
Mild periarticular soft tissue swelling without disruption of the palmar fetlock pouch
Extension of the fracture lines into the basilar (abaxial) surface with involvement of the distal sesamoidean ligament attachment (Correct answer)

Correct answer: Extension of the fracture lines into the basilar (abaxial) surface with involvement of the distal sesamoidean ligament attachment

Extension of proximal sesamoid fracture lines into the basilar surface with compromise of the distal sesamoidean ligament (DSL) attachments represents the most catastrophically poor prognostic feature. The DSLs (straight, oblique, and cruciate) are the primary stabilizers of the fetlock in weight-bearing; their avulsion renders the fetlock biomechanically unsalvageable for athletic work. This pattern, combined with biaxial comminution, essentially precludes return to racing and significantly compromises even pasture soundness. Apical fractures with a single parasagittal line, minimal displacement, and intact soft tissue structures carry a far better surgical and athletic prognosis.

Question 281: Metabolic bone disease (MBD) in captive reptiles is most commonly caused by which combination of factors?

Bacterial osteomyelitis secondary to trauma
Excess vitamin D3 supplementation
Hyperthyroidism
Calcium/phosphorus imbalance and UV-B light deficiency (Correct answer)

Correct answer: Calcium/phosphorus imbalance and UV-B light deficiency

MBD in reptiles results from inadequate dietary calcium, improper Ca:P ratios, and insufficient UV-B light for endogenous vitamin D3 synthesis.

Question 282: In a spayed female ferret presenting with vulvar swelling, which disease is the most likely diagnosis?

Ovarian remnant syndrome
Diabetes mellitus
Adrenal gland disease (Correct answer)
Insulinoma

Correct answer: Adrenal gland disease

Adrenal gland disease in ferrets causes excess sex hormone secretion from adrenocortical tissue, leading to vulvar swelling even in spayed females.

Question 283: Lily (Lilium spp.) ingestion in cats primarily targets which organ system?

Hepatic system
Renal system (Correct answer)
Cardiovascular system
Central nervous system

Correct answer: Renal system

True lily ingestion in cats causes acute renal failure due to nephrotoxic steroidal glycosides; even small amounts can be fatal.

Question 284: Intra-articular injection of which substance is used as a visco-supplementation therapy to improve synovial fluid quality in horses with joint disease?

Hyaluronic acid (sodium hyaluronate) (Correct answer)
Methylprednisolone acetate
Platelet-rich plasma (PRP)
Polysulfated glycosaminoglycan (Adequan)

Correct answer: Hyaluronic acid (sodium hyaluronate)

Sodium hyaluronate (hyaluronic acid) is injected intra-articularly to restore viscosity and lubrication of synovial fluid, acting as visco-supplementation in arthritic joints.

Question 285: A 3-year-old Thoroughbred presents with acute-onset severe lameness. Radiographs of the fetlock region are initially unremarkable. Nuclear scintigraphy (bone phase) shows a focal, intensely increased radiopharmaceutical uptake (IRU) at the palmar/plantar aspect of the proximal sesamoid bones. MRI performed 48 hours later shows a T2-hypointense linear signal defect traversing the body of the medial proximal sesamoid bone. What is the MOST likely diagnosis and its implication?

Sesamoiditis (chronic degenerative change) — requires 4-6 weeks of stall rest
Basilar fracture of the proximal sesamoid — low catastrophic failure risk if managed conservatively
Body fracture of the proximal sesamoid — high risk for catastrophic failure and suspensory apparatus breakdown (Correct answer)
Abaxial fracture of the proximal sesamoid — surgical arthroscopy is curative

Correct answer: Body fracture of the proximal sesamoid — high risk for catastrophic failure and suspensory apparatus breakdown

A T2-hypointense linear defect traversing the body of the proximal sesamoid bone represents a body fracture — the most serious type of sesamoid fracture in racehorses. Unlike apical (tip) or abaxial (side) fractures, body fractures involve the entire cross-section of the bone and risk complete disruption of the suspensory apparatus, which can cause catastrophic breakdown. The scintigraphic hot spot on the palmar/plantar aspect with subsequent MRI correlation is the advanced imaging sequence used when plain radiographs are unremarkable early in the injury. Sesamoiditis causes diffuse rather than focal linear T2 hypointensity. Basilar fractures involve the base and have a better prognosis than body fractures.

Question 286: A ferret presents with progressive hind limb weakness, muscle wasting, and hypoglycemia. Blood glucose is 45 mg/dL. The most likely diagnosis is:

Adrenal gland disease
Lymphoma
Insulinoma (Correct answer)
Aleutian disease

Correct answer: Insulinoma

Insulinoma is the most common pancreatic tumor in ferrets and classically causes episodic hypoglycemia with hind limb weakness.

Question 287: A 6-year-old cat is presented for evaluation of a suspected portosystemic shunt. Fasting ammonia is 210 µmol/L (ref <60). On abdominal ultrasound, multiple tortuous vessels are identified in the splenic and left gastric regions but no single large shunting vessel. Which statement about this cat's condition is most accurate?

Multiple acquired portosystemic shunts indicate portal hypertension, most likely from hepatic fibrosis or cirrhosis (Correct answer)
Multiple shunts in this distribution are typical of right divisional intrahepatic shunts with collateral reconstitution
This represents portal vein hypoplasia (microvascular dysplasia) with compensatory collateral formation
This pattern is consistent with a congenital extrahepatic portosystemic shunt requiring surgical attenuation

Correct answer: Multiple acquired portosystemic shunts indicate portal hypertension, most likely from hepatic fibrosis or cirrhosis

Multiple acquired portosystemic shunts (APSS) develop as a consequence of portal hypertension, typically from hepatic parenchymal disease causing increased sinusoidal resistance — most commonly hepatic fibrosis, cirrhosis, or non-cirrhotic portal hypertension in cats. Unlike congenital shunts (which are typically single large vessels), acquired shunts are multiple small vessels that open as portosystemic pressure gradients increase. In cats, hepatic lipidosis, cholangitis, and inflammatory bowel disease can drive fibrosis. Surgery is contraindicated in APSS; treating underlying hepatic disease is the goal.

Question 288: A shelter veterinarian is investigating a cluster of deaths in kittens 6–10 weeks old. Affected kittens show sudden onset of vomiting, hemorrhagic diarrhea, marked leukopenia (WBC 800/µL), and high mortality within 24–48 hours despite supportive care. Serology and PCR confirm feline panleukopenia virus (FPV). A litter of 4-week-old kittens born in the shelter to an unvaccinated queen survived without illness. Which explanation BEST accounts for the age-dependent mortality pattern?

Maternal antibodies are insufficient in neonates because FPV is a non-enveloped virus that resists passive transfer
Neonatal kittens produce higher levels of type I interferons that suppress viral replication before clinical disease
Neonates lack the mature rapidly dividing intestinal crypt cells that serve as the primary FPV replication target (Correct answer)
FPV preferentially targets bone marrow erythroid precursors in neonates, causing anemia rather than leukopenia

Correct answer: Neonates lack the mature rapidly dividing intestinal crypt cells that serve as the primary FPV replication target

FPV (a parvovirus) requires rapidly dividing cells for replication. In neonates under 4 weeks, intestinal crypt epithelium is not yet mature/rapidly dividing, so the GI tract is largely spared. Instead, FPV in neonates and fetuses targets the cerebellum (Purkinje cells during cerebellar development), causing cerebellar hypoplasia. Kittens 6–10 weeks have highly mitotically active intestinal crypts and rapidly dividing bone marrow progenitors — making them maximally susceptible. Maternal antibodies DO transfer effectively via colostrum (IgG passes via Fc receptors), but if the queen is unvaccinated, no protection is conferred.

Question 289: Which MRI finding is characteristic of syringomyelia (syrinx) in a Cavalier King Charles Spaniel with Chiari-like malformation?

T2 hypointense lesion in the dorsal columns
Contrast-enhancing ring lesion within the cord
T2 hyperintense fluid-filled cavity within the spinal cord (Correct answer)
T1 hyperintense intramedullary lesion

Correct answer: T2 hyperintense fluid-filled cavity within the spinal cord

A syrinx appears as a T2 hyperintense (fluid signal) cavity within the spinal cord parenchyma on MRI, reflecting the accumulation of CSF-like fluid.

Question 290: In a dairy herd investigation of reproductive failure, you find a 28% first-service conception rate and multiple cows with endometritis diagnosed via cytology (>18% PMNs at 21–33 days post-partum). Mycoplasma bovigenitalium is cultured from uterine swabs of several affected cows. Which of the following is MOST accurate regarding treatment of this herd?

Intrauterine infusion of oxytetracycline is the treatment of choice because Mycoplasma lacks a cell wall and oxytetracycline penetrates uterine secretions well
Prostaglandin F2α administered at diagnosis will resolve mycoplasma endometritis by inducing luteolysis and restoring estrous cyclicity
Ceftiofur intrauterine infusion is effective because third-generation cephalosporins have broad-spectrum gram-negative coverage including Mycoplasma
Mycoplasma species lack a cell wall and are therefore intrinsically resistant to all beta-lactam antibiotics; systemic fluoroquinolones or tetracyclines are more appropriate, but treatment success is poor (Correct answer)

Correct answer: Mycoplasma species lack a cell wall and are therefore intrinsically resistant to all beta-lactam antibiotics; systemic fluoroquinolones or tetracyclines are more appropriate, but treatment success is poor

Mycoplasma spp. lack a peptidoglycan cell wall, which confers intrinsic resistance to all beta-lactam antibiotics (penicillins, cephalosporins, and carbapenems) regardless of generation or spectrum (rules out A and C). Drugs targeting cell wall synthesis have no activity against cell-wall-free organisms. Tetracyclines and fluoroquinolones have in vitro activity, but clinical treatment success for Mycoplasma genital infections in cattle is notoriously poor, often requiring culling of chronically infected animals and biosecurity measures. Prostaglandin (D) supports uterine clearance in bacterial endometritis but does not address Mycoplasma specifically and is not curative.

Question 291: A 3-year-old German Shepherd Dog has progressive pelvic limb ataxia. MRI reveals an intramedullary T2-hyperintense lesion at L4 that does not contrast-enhance. The most likely diagnosis is:

Neoplasia (ependymoma)
Intervertebral disc herniation
Degenerative myelopathy
Fibrocartilaginous embolism (Correct answer)

Correct answer: Fibrocartilaginous embolism

Fibrocartilaginous embolism (FCE) typically appears as an intramedullary T2 hyperintensity without contrast enhancement, in young to middle-aged large breed dogs with acute onset.

Question 292: A veterinarian prescribes enrofloxacin 5 mg/kg IV once daily for a 6-year-old cat with bacteremia. On day 3, the owner calls reporting the cat is bumping into objects and appears disoriented. Fundic examination reveals multifocal areas of retinal degeneration. What pharmacokinetic property of fluoroquinolones in cats most directly explains this toxicity?

Cats have reduced hepatic CYP1A2 activity, leading to accumulation of the parent compound (Correct answer)
Enrofloxacin's metabolic conversion to ciprofloxacin is prolonged in cats, producing toxic peak plasma levels
Cats lack sufficient glucuronidation capacity, causing enrofloxacin to accumulate in retinal photoreceptors
Cats have a high volume of distribution for enrofloxacin, concentrating it in ocular tissues at doses safe in other species

Correct answer: Cats have reduced hepatic CYP1A2 activity, leading to accumulation of the parent compound

Cats have markedly reduced hepatic CYP1A2 (cytochrome P450 1A2) activity compared to dogs and humans. Enrofloxacin is primarily metabolized by CYP1A2 to ciprofloxacin. With impaired metabolism, the parent compound (enrofloxacin) accumulates to high plasma concentrations. Enrofloxacin — more so than ciprofloxacin — is directly retinotoxic in cats, causing acute retinal degeneration and blindness, especially at doses ≥5 mg/kg/day IV. The AVMA-recommended feline dose is ≤2.5 mg/kg/day to reduce this risk. Glucuronidation deficiency in cats is real but pertains to other drug classes (e.g., acetaminophen, aspirin), not fluoroquinolone toxicity.

Question 293: A cat presents with bilateral anterior uveitis. FIP testing is negative. Which other infectious agent should be high on the differential list?

Feline calicivirus
Feline panleukopenia virus
Feline parvovirus
Toxoplasma gondii (Correct answer)

Correct answer: Toxoplasma gondii

Toxoplasma gondii is a leading cause of feline uveitis and should be tested via serology when FIP is ruled out.

Question 294: A public health veterinarian is reviewing a food establishment's HACCP plan for a ready-to-eat deli meat facility. The plan identifies internal temperature of 160°F (71.1°C) as a Critical Control Point (CCP) for lethality. An inspector finds that logs show 12 consecutive batches reached only 158°F (70°C). Under HACCP principles, which action is MOST appropriate?

Adjust the CCP limit downward to 158°F to reflect actual operational capacity
Require immediate corrective action documentation, reassess the disposition of all 12 affected batches, and evaluate root cause (Correct answer)
Issue a warning but allow product to proceed since 158°F is close to the CCP limit
Suspend the HACCP plan and revert to traditional inspection methods pending retesting

Correct answer: Require immediate corrective action documentation, reassess the disposition of all 12 affected batches, and evaluate root cause

Under HACCP Principle 5, when a critical limit is not met, a pre-established corrective action must be implemented immediately. This includes: (1) correcting the process deviation, (2) determining the disposition of affected product (hold, test, or destroy), and (3) documenting the corrective action. All 12 batches where the CCP was not met require individual disposition decisions — they cannot proceed without evaluation. Adjusting CCP limits to match operational failure would compromise food safety integrity and violates HACCP validation requirements.

Question 295: A 5-year-old male neutered Dachshund presents with acute onset severe abdominal pain, hematemesis, and collapse. PCV is 16% with adequate total protein (6.2 g/dL). Abdominal radiographs show a mild loss of serosal detail. Coagulation panel reveals: PT 28 sec (ref 7–12), PTT 98 sec (ref 60–90), fibrinogen 80 mg/dL (ref 150–400), d-dimers markedly elevated. Platelet count is 40,000/µL. Which of the following best explains this coagulopathy pattern?

Disseminated intravascular coagulation (DIC) secondary to a systemic disease process (Correct answer)
Platelet dysfunction from aspirin ingestion with secondary hypofibrinogenemia
Inherited factor VIII deficiency (Hemophilia A) with concurrent thrombocytopenia
Vitamin K antagonist rodenticide toxicity causing factor II, VII, IX, X deficiency

Correct answer: Disseminated intravascular coagulation (DIC) secondary to a systemic disease process

The combination of prolonged PT and PTT, thrombocytopenia, markedly elevated d-dimers, and critically low fibrinogen defines DIC (both the procoagulant and fibrinolytic phases). The consumption of clotting factors AND platelets combined with d-dimer elevation (cross-linked fibrin degradation products) is the hallmark. Rodenticide toxicity causes prolonged PT (extrinsic pathway factor VII is shortest half-life) but does NOT cause thrombocytopenia or elevated d-dimers or hypofibrinogenemia. Hemophilia A causes isolated PTT prolongation. Aspirin causes platelet dysfunction (prolonged closure time/buccal mucosal bleeding time) but not this global consumptive coagulopathy. The acute abdomen with hematemesis suggests an underlying trigger (splenic mass rupture, sepsis, or neoplasia) driving the DIC.

Question 296: A beef herd experiences an 'abortion storm' in the last trimester of gestation. Histopathology of several aborted fetal brains reveals multifocal, nonsuppurative necrotizing encephalitis with associated protozoal cysts. What is the most likely etiologic agent?

Bovine Herpesvirus 1 (IBR)
Neospora caninum (Correct answer)
Leptospira interrogans
Brucella abortus

Correct answer: Neospora caninum

Neospora caninum is a leading protozoal cause of abortion in cattle, often occurring in outbreaks during the second and third trimesters. The pathognomonic lesion for neosporosis is multifocal, nonsuppurative necrotizing inflammation in the fetal brain and heart, often with identifiable protozoal cysts. IBR typically causes multifocal hepatic necrosis in the fetus, Leptospirosis causes interstitial nephritis, and Brucellosis causes severe placentitis.

Question 297: A 10-year-old female Labrador Retriever presents with a history of panting, pot-bellied appearance, bilateral symmetrical alopecia, and PU/PD. Urine cortisol:creatinine ratio is elevated. Which test best differentiates pituitary-dependent from adrenal-dependent hyperadrenocorticism?

High-dose dexamethasone suppression test (HDDST) (Correct answer)
Low-dose dexamethasone suppression test (LDDST)
ACTH stimulation test
Urine cortisol:creatinine ratio

Correct answer: High-dose dexamethasone suppression test (HDDST)

The HDDST suppresses cortisol by >50% in most pituitary-dependent cases because the tumor retains some feedback sensitivity, while adrenal tumors do not suppress.

Question 298: A cat is being anesthetized with an alfaxalone TIVA protocol for a lengthy orthopedic repair. Approximately 90 minutes into the procedure, the cat begins showing signs of awareness (purposeful movement, increased HR/BP) despite what appears to be an adequate infusion rate. Which mechanism BEST explains this phenomenon?

Tachyphylaxis to alfaxalone due to GABA-A receptor downregulation (Correct answer)
Cytochrome P450 induction causing accelerated alfaxalone metabolism
Accumulation of an active excitatory metabolite of alfaxalone
Redistribution from effect site to peripheral compartments over time

Correct answer: Tachyphylaxis to alfaxalone due to GABA-A receptor downregulation

Alfaxalone acts on GABA-A receptors (specifically the neurosteroid binding site on β subunits). With prolonged, continuous exposure, GABA-A receptor internalization and desensitization (tachyphylaxis) can occur, requiring higher infusion rates over time to maintain the same depth of anesthesia. This is a clinically documented phenomenon with alfaxalone TIVA, particularly in cats during extended procedures. CYP induction is not rapid enough to explain intraoperative changes. Redistribution (option C) would actually deepen anesthesia as context-sensitive half-time increases. Alfaxalone does not have known clinically significant excitatory metabolites.

Question 299: A 7-year-old intact male dog is being treated with ketoconazole for a systemic fungal infection. The owner also mentions the dog is on cyclosporine for immune-mediated thrombocytopenia. Which pharmacokinetic mechanism best explains the expected drug interaction between these two agents?

Ketoconazole inhibits CYP3A4, reducing cyclosporine metabolism and increasing its plasma concentration (Correct answer)
Ketoconazole displaces cyclosporine from plasma protein binding sites, increasing free drug
Ketoconazole induces P-glycoprotein, increasing cyclosporine efflux from enterocytes
Cyclosporine competitively inhibits ketoconazole absorption at intestinal transporters

Correct answer: Ketoconazole inhibits CYP3A4, reducing cyclosporine metabolism and increasing its plasma concentration

Ketoconazole is a potent inhibitor of cytochrome P450 3A4 (CYP3A4), the primary enzyme responsible for cyclosporine metabolism. Inhibition of this enzyme markedly reduces cyclosporine clearance, leading to elevated plasma concentrations and potential nephrotoxicity and neurotoxicity. Clinicians sometimes exploit this interaction intentionally to reduce cyclosporine dosing costs, but it requires careful monitoring.

Question 300: Which anatomical site is preferred for intramuscular injections in birds?

Wing web
Quadriceps muscle
Epaxial muscle
Pectoral muscle (Correct answer)

Correct answer: Pectoral muscle

The pectoral muscle is the preferred IM injection site in birds because of its large mass and easy accessibility.

Question 301: A poultry flock develops acute respiratory distress, cyanosis of the comb and wattles, and hemorrhagic tracheitis with 40% mortality over 5 days. Which disease is most consistent with these findings?

Infectious bronchitis
Newcastle disease (velogenic form)
Avian influenza (HPAI)
Infectious laryngotracheitis (ILT) (Correct answer)

Correct answer: Infectious laryngotracheitis (ILT)

Infectious laryngotracheitis, caused by Gallid alphaherpesvirus 1, presents with severe hemorrhagic tracheitis, bloody mucus, gasping, and high mortality in affected flocks.

Question 302: Which urine specific gravity value is most consistent with isosthenuria in a cat with suspected chronic kidney disease?

1.025
1.040
1.005
1.012 (Correct answer)

Correct answer: 1.012

Isosthenuria (USG 1.008–1.012) indicates the kidneys cannot concentrate or dilute urine beyond plasma osmolality, a hallmark of significant tubular dysfunction.

Question 303: A state veterinarian receives a report of a cluster of human cases of hemolytic uremic syndrome (HUS) in a rural county. Epidemiological investigation links the cases to a small farm that sells raw milk and allows petting zoo visits. Which of the following zoonotic transmission pathways is MOST likely responsible, and what is the primary regulatory authority responsible for interstate commerce of the implicated product?

Fecal-oral transmission of Escherichia coli O157:H7 via raw milk; FDA under the Grade A Pasteurized Milk Ordinance (PMO) (Correct answer)
Vector-borne transmission of Cryptosporidium parvum; EPA under the Safe Drinking Water Act
Direct contact transmission of Salmonella Typhimurium; CDC under the Public Health Service Act
Aerosol transmission of Campylobacter jejuni; USDA-FSIS under the Federal Meat Inspection Act

Correct answer: Fecal-oral transmission of Escherichia coli O157:H7 via raw milk; FDA under the Grade A Pasteurized Milk Ordinance (PMO)

E. coli O157:H7 is the classic cause of HUS, particularly in children, and raw milk is a well-documented vehicle. The FDA regulates interstate raw milk commerce under the PMO (21 CFR Part 1240.61 prohibits interstate sale of raw milk for direct human consumption). The fecal-oral route from cattle reservoirs through unpasteurized milk is the primary pathway in this scenario. Campylobacter causes gastroenteritis but rarely HUS. Cryptosporidium is waterborne and causes diarrhea, not typically HUS. USDA-FSIS covers meat/poultry, not dairy.

Question 304: Which grading scale is the standard used in the United States to assess equine lameness severity?

Obel grading system
FEI grading 0-4
British Equine Veterinary Association (BEVA) 1-10 scale
AAEP lameness scale 0-5 (Correct answer)

Correct answer: AAEP lameness scale 0-5

The American Association of Equine Practitioners (AAEP) 0-5 lameness scale is the standard used in the US, with 0 being sound and 5 being non-weight-bearing.

Question 305: A 10-year-old mixed-breed dog presents with weight gain, alopecia, hyperpigmentation, and a pot-bellied appearance. Urine cortisol:creatinine ratio is elevated. LDDS test shows no suppression. HDDS test shows >50% suppression. What is the most likely diagnosis?

Hypoadrenocorticism
Adrenal-dependent hyperadrenocorticism
Pituitary-dependent hyperadrenocorticism (Correct answer)
Iatrogenic hyperadrenocorticism

Correct answer: Pituitary-dependent hyperadrenocorticism

Suppression on the high-dose dexamethasone suppression test (>50%) indicates the excess ACTH source is pituitary-dependent (PDH).

Question 306: A 6-year-old Maine Coon cat presents in acute respiratory distress. Physical exam reveals a heart murmur, gallop rhythm, and crackles on lung auscultation. A thoracic radiograph shows cardiomegaly and pulmonary edema. Echocardiography confirms hypertrophic cardiomyopathy (HCM). In addition to oxygen therapy, which medication is most critical for initial stabilization of this cat's congestive heart failure?

Benazepril
Atenolol
Furosemide (Correct answer)
Clopidogrel

Correct answer: Furosemide

Furosemide, a potent loop diuretic, is the most critical initial medication for a cat in congestive heart failure (CHF) secondary to HCM. Its primary function is to reduce fluid volume by promoting urination, which alleviates pulmonary edema and relieves respiratory distress. Clopidogrel is an anti-platelet drug used to prevent aortic thromboembolism but does not treat CHF. Atenolol (a beta-blocker) and benazepril (an ACE inhibitor) may be used for long-term management but are not the first-line emergency drugs for reducing pulmonary edema.

Question 307: Would you ever administer antibiotics to a cat with FIP?

Yes (Correct answer)
No

Correct answer: Yes

While FIP is a viral disease and antibiotics do not directly treat the virus, they are often administered to FIP patients. Cats with FIP are immunocompromised and highly susceptible to secondary bacterial infections, which can complicate the disease and worsen their condition. Antibiotics are used to manage these opportunistic bacterial infections.

Question 308: During a toxicology consult, you receive a call about a cat that ingested permethrin-containing dog spot-on approximately 1 hour ago. The cat is currently showing mild whole-body tremors and hypersalivation. The owner asks about inducing emesis at home with hydrogen peroxide. What is the most accurate and complete response?

Instruct the owner to administer xylazine orally as a safer emetic, then transport the cat
Hydrogen peroxide is unreliable for emesis induction in cats and is contraindicated — instruct the owner to bring the cat in immediately for methocarbamol therapy and professional decontamination (Correct answer)
Do not induce emesis; the neurological signs indicate the window for decontamination benefit has passed and emesis risks aspiration
Hydrogen peroxide can be used at 1 mL/kg PO; the owner should administer it once and transport immediately

Correct answer: Hydrogen peroxide is unreliable for emesis induction in cats and is contraindicated — instruct the owner to bring the cat in immediately for methocarbamol therapy and professional decontamination

Hydrogen peroxide is a dangerous and ineffective emetic in cats. Unlike dogs, cats do not reliably vomit in response to hydrogen peroxide, and it causes severe hemorrhagic gastroenteritis in this species. The appropriate feline emetics are dexmedetomidine (IM) or xylazine (IM/IV) administered by a veterinarian — never orally at home. Furthermore, although neurological signs are mild, the presence of tremors signals CNS involvement and increases aspiration risk with any emetic. The owner should immediately transport the cat for professional decontamination (bathing with dish soap to remove dermal permethrin), methocarbamol (muscle relaxant of choice for pyrethroid-induced tremors in cats), IV fluid support, and thermoregulation. Pyrethroids are not absorbed through the GI mucosa as efficiently as through skin, so dermal decontamination is the priority.

Question 309: A 7-year-old, neutered male Golden Retriever is presented with a chief complaint of weight gain, lethargy, and a 'rat tail' (alopecia on the tail). Physical examination reveals a dull coat, truncal alopecia, and mild obesity. Which of the following clinicopathologic abnormalities would be most supportive of a diagnosis of hypothyroidism?

Hyperglycemia
Increased ALT and ALKP
Hypercholesterolemia (Correct answer)
Low BUN and creatinine

Correct answer: Hypercholesterolemia

The clinical signs described are classic for canine hypothyroidism. Due to the decreased metabolic rate associated with hypothyroidism, hypercholesterolemia is a very common finding on a serum biochemistry panel, present in about 75% of cases. While a mild, non-regenerative anemia may also be seen, hypercholesterolemia is the most consistent biochemical abnormality.

Question 310: Which of the following reproductive strategies describes the boa constrictor?

Viviparous — has a true placenta like mammals
Oviparous — lays eggs that develop externally
Parthenogenetic — reproduces without fertilization
Ovoviviparous — retains eggs internally and gives birth to live young (Correct answer)

Correct answer: Ovoviviparous — retains eggs internally and gives birth to live young

Boa constrictors are ovoviviparous; eggs are retained and develop internally with the female giving birth to live young without a true placenta.

Question 311: A 2-year-old sheep presents with acute blindness, head pressing, and opisthotonus. The animal has been on a high-grain diet with limited forage. Blood thiamine levels are low. Which treatment should be administered immediately?

Magnesium sulfate IV to treat suspected hypomagnesemia
Intravenous dextrose 50% at 0.5 mL/kg
Thiamine (vitamin B1) 10–20 mg/kg IV or IM (Correct answer)
Dexamethasone 0.1 mg/kg IV to reduce cerebral edema

Correct answer: Thiamine (vitamin B1) 10–20 mg/kg IV or IM

Polioencephalomalacia (PEM) in sheep is caused by thiamine deficiency, often triggered by high-grain diets that favor thiaminase-producing rumen bacteria. Clinical signs include blindness, cortical signs, and opisthotonus. Immediate high-dose thiamine (B1) administration is the treatment of choice. Dextrose worsens thiamine deficiency; dexamethasone is adjunctive at best.

Question 312: Abdominal ultrasound in a 9-year-old spayed Labrador reveals a 3.2 cm splenic mass with a heterogeneous echotexture containing multiple anechoic cavities and a hyperechoic rim. Doppler interrogation shows no internal vascularity within the cavities. Fine-needle aspirate of the solid component yields blood only. Which imaging feature most strongly argues AGAINST a diagnosis of splenic hemangioma in favor of hemangiosarcoma?

Absence of internal Doppler signal within the cavities
Anechoic cavities within the mass representing blood-filled sinusoids
Simultaneous detection of a hypoechoic hepatic nodule with similar internal architecture (Correct answer)
Hyperechoic peripheral rim representing compressed splenic parenchyma

Correct answer: Simultaneous detection of a hypoechoic hepatic nodule with similar internal architecture

Splenic hemangioma and hemangiosarcoma can appear nearly identical on ultrasound — both produce heterogeneous masses with blood-filled cavities, and non-diagnostic FNA is common in both. The single most distinguishing imaging feature suggesting malignancy (hemangiosarcoma) is multifocal involvement: a synchronous hepatic lesion with the same architecture strongly implies metastatic hemangiosarcoma, as the liver is the most common metastatic site. Anechoic cavities and absent Doppler flow within cavities are seen in both benign and malignant vascular tumors. The hyperechoic rim is a nonspecific finding seen with any expansile splenic mass causing parenchymal compression.

Question 313: A 7-year-old Labrador Retriever presents with polyuria, polydipsia, and bilateral cataracts. Fasting blood glucose is 420 mg/dL. Which insulin type is most commonly used for initial management of canine diabetes mellitus?

NPH insulin (Correct answer)
Regular insulin
Detemir (Levemir)
Glargine (Lantus)

Correct answer: NPH insulin

NPH insulin is the first-line choice for canine diabetes mellitus due to its intermediate duration matching the dog's twice-daily feeding schedule.

Question 314: Tritrichomonas foetus causes large-bowel diarrhea in cats. Which drug is currently recommended for treatment despite limited efficacy data?

Sulfadimethoxine
Fenbendazole
Ronidazole (Correct answer)
Metronidazole

Correct answer: Ronidazole

Ronidazole is the only drug shown to eliminate Tritrichomonas foetus in cats, though resistance and neurotoxicity at high doses are concerns.

Question 315: A 10-year-old diabetic cat is scheduled for dental extraction. Which inhalant anesthetic is preferred due to its lower solubility and faster recovery profile?

Enflurane
Isoflurane
Halothane
Sevoflurane (Correct answer)

Correct answer: Sevoflurane

Sevoflurane has the lowest blood-gas partition coefficient among commonly used veterinary inhalants, resulting in the fastest induction and recovery.

Question 316: A 4-year-old Labrador Retriever presents with acute respiratory distress after ingesting rat poison 2 days ago. PT and aPTT are severely prolonged; patient has pleural hemorrhage. Which rodenticide is most likely responsible?

Brodifacoum (second-generation anticoagulant) (Correct answer)
Zinc phosphide
Strychnine
Bromethalin

Correct answer: Brodifacoum (second-generation anticoagulant)

Second-generation anticoagulant rodenticides like brodifacoum inhibit vitamin K epoxide reductase, causing prolonged coagulopathy and hemorrhage 1–5 days post-ingestion.

Question 317: A 6-year-old male intact Beagle presents with a 4-month history of recurrent urinary tract infections and intermittent hematuria. Ultrasound reveals a 2.8 cm hyperechoic mass in the prostatic urethra. Biopsy confirms transitional cell carcinoma (TCC). Thoracic radiographs are clear. Which statement regarding treatment and prognosis is MOST accurate?

Surgical resection via total prostatectomy is curative in >50% of cases if margins are clean
Urethral stenting is contraindicated because it promotes tumor seeding along the stent tract
Piroxicam alone provides equivalent survival to piroxicam plus mitoxantrone combination therapy
COX-2 inhibitor therapy is indicated regardless of other treatment modality due to documented partial response rates (Correct answer)

Correct answer: COX-2 inhibitor therapy is indicated regardless of other treatment modality due to documented partial response rates

Canine TCC (now termed urothelial carcinoma) overexpresses COX-2, and piroxicam (a non-selective COX inhibitor) has documented partial response rates (~17%) and stable disease rates (~57%), making it a cornerstone of TCC management regardless of whether chemotherapy is added. Piroxicam plus mitoxantrone has shown improved response rates over piroxicam alone in studies (not equivalent). Surgical resection is rarely curative due to urethral/trigone involvement and high local recurrence. Urethral stenting is actually used palliatively for urethral obstruction in TCC dogs, with tumor seeding along stent tracts not a documented clinical contraindication.

Question 318: Gabapentin is increasingly used in veterinary patients for chronic and neuropathic pain. What is its primary mechanism of action?

Voltage-gated calcium channel alpha-2-delta subunit inhibition (Correct answer)
NMDA glutamate receptor blockade
Mu-opioid receptor agonism
Cyclooxygenase-2 inhibition

Correct answer: Voltage-gated calcium channel alpha-2-delta subunit inhibition

Gabapentin binds to the alpha-2-delta subunit of voltage-gated calcium channels in the dorsal horn of the spinal cord, reducing excitatory neurotransmitter release and dampening central sensitization.

Question 319: A radiograph of a 3-year-old Quarter Horse reveals periarticular bone proliferation and subchondral bone lucency at the distal interphalangeal joint with a linear radiolucent defect extending from the articular surface of the distal phalanx. This finding is MOST consistent with:

Palmar/plantar process fracture of the distal phalanx
Subchondral bone cyst (osseous cyst-like lesion) (Correct answer)
Keratoma
Septic pedal osteitis

Correct answer: Subchondral bone cyst (osseous cyst-like lesion)

Osseous cyst-like lesions (subchondral bone cysts) of the distal phalanx in horses appear as radiolucent defects communicating with the articular surface, typically at the distal interphalangeal joint. The periarticular new bone production and the subchondral lucency with articular communication are hallmark findings. Palmar/plantar process fractures are linear lucencies at the palmar/plantar aspect of P3 not centered on the articular surface. Keratoma is a space-occupying soft tissue lesion within the hoof capsule causing focal pressure remodeling of the solar margin. Septic pedal osteitis produces irregular lysis without the discrete cyst-like architecture.

Question 320: During abdominal ultrasound, the normal feline adrenal gland has which characteristic appearance?

Oval homogeneous hyperechoic structure, 5-10mm length
Elongated hyperechoic structure parallel to the aorta, 15-20mm length
Bilobed hypoechoic structure with a hyperechoic medulla, less than 4.3mm width (Correct answer)
Round anechoic structure adjacent to the kidney, 3-5mm diameter

Correct answer: Bilobed hypoechoic structure with a hyperechoic medulla, less than 4.3mm width

Normal feline adrenal glands are bilobed (peanut-shaped) with a hypoechoic cortex and hyperechoic medulla, measuring less than 4.3mm in width.

Question 321: Which feline coronavirus (FCoV) mutation is classically associated with the transition from enteric infection to feline infectious peritonitis (FIP)?

Nucleocapsid gene frameshift
3c gene loss-of-function mutation (Correct answer)
Spike protein S1 domain deletion
7b gene duplication

Correct answer: 3c gene loss-of-function mutation

Loss-of-function mutations in the 3c gene of feline enteric coronavirus are associated with the shift to macrophage tropism and development of FIP.

Question 322: A 7-year-old cat with hyperthyroidism is well-controlled on methimazole. The owner reports the cat has developed facial pruritus, excoriations, and a mild leukopenia on recent CBC. What is the MOST appropriate next step?

Continue methimazole and treat the pruritus symptomatically; leukopenia is expected and not clinically significant
Discontinue methimazole immediately and transition to radioactive iodine (I-131) or surgical thyroidectomy after stabilization (Correct answer)
Reduce the methimazole dose by 50% and add prednisolone to manage the immune-mediated reaction
Switch to carbimazole, as it has a completely different adverse effect profile than methimazole

Correct answer: Discontinue methimazole immediately and transition to radioactive iodine (I-131) or surgical thyroidectomy after stabilization

Facial pruritus/excoriations and hematologic abnormalities (leukopenia, thrombocytopenia, agranulocytosis) are recognized adverse effects of methimazole in cats, occurring in approximately 15–20% of treated cats. Agranulocytosis is the most life-threatening hematologic complication. When these reactions occur, methimazole must be discontinued — not dose-reduced — because rechallenge carries high risk of recurrence. Carbimazole is a prodrug that is converted to methimazole in vivo, so it carries the same adverse effect risk and is NOT a safe alternative. After methimazole withdrawal and patient stabilization, definitive therapy (radioactive iodine or surgical thyroidectomy) is the recommended path forward.

Question 323: Which reproductive toxin produced by endophyte-infected tall fescue grass causes 'summer slump' and reduced pregnancy rates in beef cows?

Fumonisin B1
Zearalenone
Deoxynivalenol
Ergovaline (Correct answer)

Correct answer: Ergovaline

Ergovaline from the Neotyphodium coenophialum endophyte causes vasoconstriction, hyperthermia, and poor reproductive performance in cattle grazing infected fescue.

Question 324: Which principle of disease prevention is represented by routine vaccination of dogs against rabies in the US?

Quaternary prevention
Secondary prevention through early detection
Tertiary prevention
Primary prevention by reducing exposure and susceptibility (Correct answer)

Correct answer: Primary prevention by reducing exposure and susceptibility

Routine rabies vaccination is a primary prevention strategy that reduces the reservoir of infection and prevents the disease from occurring.

Question 325: Which ultrasonographic finding is MOST consistent with gastric dilatation-volvulus (GDV) versus simple dilatation in a dog?

Uniform gastric distension with fluid content
Compartmentalization of the stomach into two gas-filled regions on the right lateral view (Correct answer)
Thickening of the gastric wall with loss of wall layering
Inability to obtain gastric images due to gas artifact

Correct answer: Compartmentalization of the stomach into two gas-filled regions on the right lateral view

GDV causes the stomach to rotate, creating a compartmentalized 'double bubble' appearance, whereas simple dilatation shows uniform distension.

Question 326: A veterinarian working for a state health department is asked to evaluate a One Health surveillance system for Brucella melitensis in small ruminants. Which epidemiological measure best quantifies the probability that an animal testing positive by ELISA truly has brucellosis when the true prevalence in the population is 1%?

Negative predictive value
Specificity
Sensitivity
Positive predictive value (Correct answer)

Correct answer: Positive predictive value

Positive predictive value (PPV) is the probability that a test-positive animal is truly infected and is critically dependent on the prevalence of disease in the tested population. At low prevalence (1%), even a highly specific test will yield a low PPV, generating many false positives. Sensitivity measures the test's ability to correctly identify true positives; specificity measures correct identification of true negatives. Neither sensitivity nor specificity alone accounts for disease prevalence, making PPV the correct measure in this clinical and public health decision-making context.

Question 327: A 400-cow dairy herd has a 21-day pregnancy rate of 12% despite adequate submission rates. Progesterone assays on Day 7 post-insemination show adequate luteal function in 85% of cows. Uterine cytology at Day 14 post-calving reveals >18% polymorphonuclear cells (PMNs) in 35% of cows. Which intervention is MOST likely to improve the 21-day pregnancy rate in this herd?

Administer GnRH at AI to improve ovulation rate in cows with subclinical endometritis
Increase the voluntary waiting period from 50 to 70 days to reduce early postpartum inseminations
Implement a blanket intrauterine cephapirin infusion protocol at 7 days post-calving
Add a presynchronization protocol (Presynch-Ovsynch) before initiating timed AI (Correct answer)

Correct answer: Add a presynchronization protocol (Presynch-Ovsynch) before initiating timed AI

With adequate luteal function but low 21-day pregnancy rate, the bottleneck is likely poor synchrony and ovulation at the time of AI rather than progesterone insufficiency. Presynchronization (Presynch-Ovsynch) improves follicular wave synchrony before the Ovsynch protocol, increasing the proportion of cows that respond with a dominant follicle and ovulate at timed AI — consistently shown to raise pregnancy per AI by 5–10 percentage points. Blanket cephapirin infusion is not recommended due to antimicrobial stewardship concerns and no proven efficacy for subclinical endometritis at 7 days. GnRH at AI addresses ovulation failure but does not address poor synchronization upstream. Extending the VWP would reduce submission rate, worsening the 21-day pregnancy rate.

Question 328: A 6-month-old calf dies acutely. Necropsy reveals a 'paint-brush' hemorrhage pattern on the epicardium, fibrinonecrotic plaques in the abomasum, and hemorrhagic lymph nodes. Which pathologic process most likely caused these lesions?

Vitamin E/selenium deficiency (white muscle disease)
Johne's disease with chronic protein-losing enteropathy
Septicemia with gram-negative lipopolysaccharide-mediated disseminated intravascular coagulation (DIC) (Correct answer)
Copper toxicity with intravascular hemolysis

Correct answer: Septicemia with gram-negative lipopolysaccharide-mediated disseminated intravascular coagulation (DIC)

Petechial/ecchymotic hemorrhages (paint-brush pattern) on serosal surfaces combined with hemorrhagic lymph nodes and mucosal necrosis are classic findings of endotoxemia-induced DIC in calves, most commonly from gram-negative septicemia (e.g., Salmonella, E. coli). LPS activates the coagulation cascade, consuming clotting factors and causing bleeding diathesis. White muscle disease shows pale streaking of skeletal/cardiac muscle.

Question 329: Which toxin from Rhododendron spp. causes salivation, vomiting, bradycardia, and hypotension in cats by activating sodium channels?

Andromedotoxin and grayanotoxin are the same compound (Correct answer)
Grayanotoxin
Taxine
Andromedotoxin

Correct answer: Andromedotoxin and grayanotoxin are the same compound

Grayanotoxin and andromedotoxin are synonymous names for the same sodium channel-activating diterpene in Rhododendron/Azalea plants.

Question 330: On MRI, T2-weighted sequences are MOST useful for identifying:

Fluid-filled structures and edema (Correct answer)
Cortical bone detail
Calcified lesions
Gas within tissues

Correct answer: Fluid-filled structures and edema

T2-weighted MRI sequences produce high signal (bright) from fluid, making them ideal for identifying edema, effusions, and fluid-filled structures.

Question 331: A 6-year-old cat is referred for evaluation of refractory hypertension (BP consistently >200 mmHg systolic) unresponsive to amlodipine at 0.625 mg/cat PO q24h. Serum aldosterone is markedly elevated. Abdominal CT reveals a 1.2 cm unilateral adrenal mass. Which diagnosis best explains this clinical picture, and what is the definitive treatment?

Pheochromocytoma; adrenalectomy after pre-operative alpha-blockade with phenoxybenzamine
Adrenal-dependent hyperadrenocorticism; trilostane therapy
Primary hyperaldosteronism (Conn's syndrome); adrenalectomy or medical management with spironolactone (Correct answer)
Adrenal carcinoma with ectopic ACTH secretion; palliative mitotane

Correct answer: Primary hyperaldosteronism (Conn's syndrome); adrenalectomy or medical management with spironolactone

Feline primary hyperaldosteronism (Conn's syndrome) is an underrecognized cause of refractory systemic hypertension in cats. It results from autonomous aldosterone secretion (usually by an adrenal adenoma or carcinoma), causing sodium retention, hypokalemia, and pressure-resistant hypertension. Markedly elevated aldosterone with a unilateral adrenal mass is the classic presentation. Definitive treatment is unilateral adrenalectomy; medical management with the mineralocorticoid antagonist spironolactone ± potassium supplementation is used when surgery is not feasible. Pheochromocytoma causes catecholamine excess (not aldosterone excess) and would require phenoxybenzamine pre-operatively. Hyperadrenocorticism does not typically cause marked aldosterone elevation.

Question 332: A 5-year-old dog presents with peracute collapse, pale mucous membranes, and abdominal distension. FAST ultrasound reveals free abdominal fluid and a splenic mass. PCV is 18%. Which statement is most accurate regarding the splenic mass?

Splenectomy is contraindicated until coagulopathy is corrected
Approximately 50% of splenic masses in dogs are malignant (hemangiosarcoma) (Correct answer)
Most splenic masses in dogs are benign hematomas
Fine needle aspirate is diagnostic in the majority of splenic masses

Correct answer: Approximately 50% of splenic masses in dogs are malignant (hemangiosarcoma)

In dogs with splenic masses and hemoabdomen, approximately 50% are hemangiosarcoma (malignant), 25% are other malignancies, and only 25% are benign nodular hyperplasia or hematoma.

Question 333: A 10-week-old female Maltese puppy is presented for her first physical examination. On auscultation, you detect a continuous, 'machinery-like' murmur, heard best over the left heart base. The puppy is otherwise bright and alert. Which of the following is the most likely diagnosis?

Mitral Valve Dysplasia
Ventricular Septal Defect
Pulmonic Stenosis
Patent Ductus Arteriosus (Correct answer)

Correct answer: Patent Ductus Arteriosus

A continuous, machinery-like murmur heard best at the left heart base in a young dog is pathognomonic for a left-to-right shunting Patent Ductus Arteriosus (PDA). This occurs because the ductus arteriosus, a vessel that bypasses the lungs in the fetus, fails to close after birth, causing a constant flow of blood from the high-pressure aorta to the lower-pressure pulmonary artery.

Question 334: A 9-year-old Paint Horse gelding presents with a 3-month history of weight loss, fever of unknown origin, and a firm, non-painful enlargement in the inguinal region. Aspiration reveals thick, greenish pus. What is the most likely diagnosis?

Squamous cell carcinoma of the inguinal lymph node
Strangles (Streptococcus equi subsp. equi) abscessation
Inguinal hernia strangulation
Ulcerative lymphangitis (Corynebacterium pseudotuberculosis abscess) (Correct answer)

Correct answer: Ulcerative lymphangitis (Corynebacterium pseudotuberculosis abscess)

Corynebacterium pseudotuberculosis causes caseous lymphadenitis (pigeon fever) with characteristic thick, greenish pus in firm subcutaneous or inguinal abscesses, often with systemic signs.

Question 335: A producer wants to reduce the risk of hardware disease (traumatic reticuloperitonitis) in his dairy herd. What is the most cost-effective preventive measure?

Feeding chopped hay to slow rumen contractions
Vaccinating with Clostridium perfringens toxoid
Installing metal detectors on TMR feeders only
Administering rumen magnets to all cows (Correct answer)

Correct answer: Administering rumen magnets to all cows

A permanent ceramic or bar magnet placed in the reticulum captures ingested ferrous metal objects, preventing them from penetrating the reticulum wall.

Question 336: A dairy herd has an elevated somatic cell count (SCC) averaging 500,000 cells/mL. What SCC threshold is used by the USDA as the legal limit for Grade A milk in the US?

750,000 cells/mL (Correct answer)
250,000 cells/mL
1,000,000 cells/mL
400,000 cells/mL

Correct answer: 750,000 cells/mL

The US legal limit for bulk tank SCC in Grade A milk is 750,000 cells/mL, though the EU standard is stricter at 400,000 cells/mL.

Question 337: A 9-year-old spayed female Bernese Mountain Dog is evaluated for a 6-month history of polyuria/polydipsia, weight loss, and a pendulous abdomen. Bloodwork shows a persistent lymphopenia (400 cells/μL), eosinopenia, elevated ALP (1,800 U/L), and mildly elevated ALT. Urine cortisol:creatinine ratio is elevated on two morning samples. A low-dose dexamethasone suppression test (LDDST) shows less than 50% suppression at 4 hours but greater than 50% suppression at 8 hours. What is the MOST appropriate next diagnostic step?

Endogenous ACTH concentration measurement
High-dose dexamethasone suppression test (HDDST) to confirm PDH vs. ADH
Adrenal ultrasonography to rule out adrenal-dependent hyperadrenocorticism
No further testing is needed; the 8-hour suppression pattern is diagnostic for pituitary-dependent hyperadrenocorticism (PDH) (Correct answer)

Correct answer: No further testing is needed; the 8-hour suppression pattern is diagnostic for pituitary-dependent hyperadrenocorticism (PDH)

In interpreting the LDDST, suppression of cortisol to <50% of baseline at the 4-hour or 8-hour time point is diagnostic for PDH (pituitary-dependent hyperadrenocorticism). When there is escape at 4 hours but suppression at 8 hours, this pattern (called 'delayed suppression') is considered diagnostic for PDH with approximately 98% specificity — meaning no further differentiation testing is required. The 8-hour suppression (>50% below baseline) essentially rules out an autonomously functioning adrenal tumor, which would not suppress at any time point. An HDDST would be redundant, and while ultrasound and endogenous ACTH are useful adjuncts, the 8-hour LDDST suppression pattern alone confirms PDH.

Question 338: A veterinary technician performing a loco-regional block for feline dental extractions inadvertently injects bupivacaine 0.5% at a total dose of 4 mg/kg. Within 10 minutes the cat develops ventricular tachycardia refractory to lidocaine administration. Which treatment is MOST likely to restore sinus rhythm?

IV bretylium tosylate 5 mg/kg as an alternative antiarrhythmic
IV lipid emulsion (20%) 1.5 mL/kg bolus followed by a CRI (Correct answer)
IV sodium bicarbonate 1 mEq/kg to alkalinize plasma and displace bupivacaine from sodium channels
Immediate cardioversion with 2 J/kg biphasic defibrillation

Correct answer: IV lipid emulsion (20%) 1.5 mL/kg bolus followed by a CRI

Bupivacaine systemic toxicity produces cardiotoxicity that is notoriously refractory to standard antiarrhythmics and resuscitation because the drug avidly binds cardiac sodium channels. Intravenous lipid emulsion (ILE) therapy ('lipid rescue') works by creating a lipid sink that sequesters the highly lipophilic bupivacaine away from cardiac tissue, rapidly reducing free plasma concentrations. The protocol is 1.5 mL/kg of 20% lipid emulsion IV bolus, followed by a CRI of 0.25 mL/kg/min for 10–60 minutes. Sodium bicarbonate helps with lidocaine toxicity and can transiently help sodium-channel blockade but is not the primary rescue therapy for bupivacaine cardiac arrest. Bretylium is no longer commercially available in North America. Electrical cardioversion does not address the pharmacologic cause and is unlikely to maintain sinus rhythm while bupivacaine is still bound to channels.

Question 339: Which NSAID is FDA-approved for long-term pain management in cats in the United States?

Ketoprofen
Robenacoxib (Correct answer)
Grapiprant
Meloxicam

Correct answer: Robenacoxib

Robenacoxib (Onsior) is the only NSAID approved for longer-term use in cats in the US; meloxicam is approved for single-dose injection only.

Question 340: A cattery owner presents with a problem of recurrent feline calicivirus (FCV) outbreaks despite strict vaccination protocols using modified-live calicivirus vaccines. PCR confirms FCV in affected cats. Affected cats display high fever (>106°F), facial and limb edema, skin ulceration, and 40% case fatality rate — a pattern different from classic FCV upper respiratory disease. Which statement BEST characterizes the virological basis of this outbreak and the limitation of current vaccines?

VS-FCV outbreaks are caused by FCV recombination with feline coronavirus, creating a chimeric virus not covered by monovalent vaccines
Current vaccines fail because VS-FCV exclusively targets macrophages via a different receptor (junctional adhesion molecule-1 rather than feline junctional adhesion molecule)
Virulent systemic FCV (VS-FCV) strains have undergone antigenic drift sufficient to escape neutralizing antibodies induced by vaccine strains, as FCV has an ssRNA genome with high mutation rates (Correct answer)
VS-FCV is a prion-mediated conformational variant of classic FCV that is resistant to inactivation by standard disinfectants used in cattery settings

Correct answer: Virulent systemic FCV (VS-FCV) strains have undergone antigenic drift sufficient to escape neutralizing antibodies induced by vaccine strains, as FCV has an ssRNA genome with high mutation rates

Virulent systemic FCV (VS-FCV or hemorrhagic fever-like FCV) represents highly pathogenic FCV strains capable of causing systemic disease with high mortality. FCV is a positive-sense single-stranded RNA virus (Caliciviridae) with a high mutation rate, allowing continuous antigenic drift. Studies have demonstrated that VS-FCV strains show reduced cross-neutralization by antibodies raised against vaccine strains — a key reason why fully vaccinated cats in outbreaks can still become severely ill. FCV does not recombine with coronavirus. Feline junctional adhesion molecule (fJAM-A) is the receptor for both classic and VS-FCV strains. VS-FCV is not prion-mediated. FCV is susceptible to bleach (1:32 dilution) but survives many quaternary ammonium compounds.

Question 341: A public health veterinarian is investigating a Q fever outbreak among abattoir workers processing pregnant ewes. Serology confirms acute Coxiella burnetii infection in 14 of 22 workers. Which of the following control measures has the STRONGEST evidence base for reducing occupational exposure in this specific setting, and which worker subpopulation requires the most rigorous exclusion from the work area?

Universal use of N95 respirators alone is sufficient; elderly workers over 65 are the highest-risk group due to cardiac complications
Negative-pressure isolation of lambing/kidding and parturition areas combined with high-efficiency particulate air (HEPA) filtration; pregnant women and immunocompromised workers require exclusion due to risk of chronic Q fever and adverse pregnancy outcomes (Correct answer)
Pre-exposure vaccination of all workers with Phase I killed whole-cell vaccine; workers with prior Coxiella seropositivity are the primary exclusion group due to hypersensitivity reactions
Antibiotic prophylaxis with doxycycline for all exposed workers; workers with valvular heart disease require exclusion due to endocarditis risk

Correct answer: Negative-pressure isolation of lambing/kidding and parturition areas combined with high-efficiency particulate air (HEPA) filtration; pregnant women and immunocompromised workers require exclusion due to risk of chronic Q fever and adverse pregnancy outcomes

C. burnetii is shed in massive quantities in placental tissues, birth fluids, and feces of parturient ruminants. Engineering controls (negative pressure, HEPA filtration) combined with PPE provide the strongest occupational protection. Pregnant women face risk of placentitis, spontaneous abortion, and premature birth; immunocompromised individuals risk chronic Q fever (endocarditis, hepatitis). While Australian Q-VAX exists, pre-exposure skin testing is mandatory due to severe hypersensitivity in previously sensitized individuals — making 'universal vaccination without testing' incorrect. Doxycycline prophylaxis is not standard practice for all exposed workers. Workers with valvular disease are high-risk for chronic infection but are not the primary exclusion group in the parturition work context.

Question 342: You are managing post-operative pain in a 5-year-old cat that underwent a thoracotomy. The patient is receiving buprenorphine (0.02 mg/kg IV q6h) but pain scores remain moderate. You elect to add a lidocaine CRI. At which dose range is intravenous lidocaine CRI generally considered safe for analgesic use in cats, given their known species-specific sensitivity to its CNS toxic effects?

25–50 mcg/kg/min
1–3 mcg/kg/min (Correct answer)
5–10 mcg/kg/min
10–20 mcg/kg/min

Correct answer: 1–3 mcg/kg/min

Cats are highly sensitive to lidocaine toxicity compared to dogs, primarily due to differences in hepatic metabolism (reduced glucuronidation capacity) and a narrower therapeutic index. Analgesic lidocaine CRIs in cats are typically used at 1–3 mcg/kg/min — dramatically lower than the 25–80 mcg/kg/min used in dogs. Doses above this range in cats risk CNS toxicity (seizures, ataxia) and cardiovascular depression. This pharmacokinetic difference is a classic NAVLE distinction between feline and canine anesthetic protocols.

Question 343: A 2-year-old intact male DSH cat from a multi-cat household presents with progressive weight loss, anorexia, and a palpable abdominal mass. Abdominal effusion is present, and fluid analysis reveals a protein concentration of 5.8 g/dL, a Rivalta test that is positive, and a cell count of 4,200 cells/μL (predominantly non-degenerate neutrophils and macrophages). An immunofluorescence assay on the effusion detects coronavirus antigen within macrophages. Which statement BEST describes the pathogenesis underlying this cat's condition?

FIP develops exclusively in cats with concurrent FeLV or FIV co-infection, which suppresses regulatory T-cell responses and permits macrophage invasion.
A biotype shift from enteric coronavirus to FIP virus occurs via two key mutations in the spike protein receptor-binding domain and the 3c accessory gene, enabling macrophage tropism and systemic spread. (Correct answer)
Antibody-dependent enhancement allows serum anti-coronavirus IgG to facilitate viral entry into macrophages via Fc receptors, and this is the sole mechanism of monocyte/macrophage infection.
The cat was infected with a highly virulent serotype II feline coronavirus strain acquired horizontally from a shedding cat, bypassing the need for any mutational events.

Correct answer: A biotype shift from enteric coronavirus to FIP virus occurs via two key mutations in the spike protein receptor-binding domain and the 3c accessory gene, enabling macrophage tropism and systemic spread.

FIP arises from in-host mutation of feline enteric coronavirus (FECV), most critically in the spike protein (affecting cell tropism) and the 3c gene (disrupting immune evasion), converting FECV into FIP virus (FIPV) with macrophage-tropic capability. This internal mutation model—not horizontal transmission of a FIPV strain—is the current consensus. Co-infection with FeLV/FIV is a risk factor but not a prerequisite. Antibody-dependent enhancement may play a contributory role but is not the sole or primary mechanism.

Question 344: During fluoroscopic evaluation of a 9-month-old Labrador Retriever with regurgitation, barium swallow demonstrates a persistent filling defect in the dorsal esophagus at the level of the heart base that does not change shape with peristalsis. A 'reversed 3 sign' or 'E sign' is noted on the aortic knob region. What is the most likely diagnosis?

Aberrant left subclavian artery causing extrinsic esophageal compression
Persistent right aortic arch (PRAA) with secondary megaesophagus (Correct answer)
Esophageal foreign body at the thoracic inlet
Esophageal leiomyoma at the gastroesophageal junction

Correct answer: Persistent right aortic arch (PRAA) with secondary megaesophagus

The classic radiographic and fluoroscopic presentation of persistent right aortic arch (PRAA) in a young large-breed dog includes: cranial esophageal dilation (megaesophagus cranial to the heart base), a persistent filling defect at the level of the heart base that does not peristalse away, and — on plain radiographs or fluoroscopy — a 'reversed 3 sign' or 'E sign' on the left lateral view, reflecting the anomalous aortic arch indenting the esophagus. PRAA is the most common vascular ring anomaly in dogs. Aberrant left subclavian artery causes a more caudal/lateral compression and lacks the classic reversed-3 sign. The location (heart base, not thoracic inlet) excludes foreign body.

Question 345: A 5-year-old Great Dane presents with sudden gastric dilation. Radiographs confirm gastric dilatation-volvulus (GDV). After stabilization and surgery, which procedure should be performed concurrently to prevent recurrence?

Pyloromyotomy
Splenectomy in all cases
Gastropexy (Correct answer)
Esophageal banding

Correct answer: Gastropexy

Gastropexy permanently affixes the stomach to the body wall and reduces GDV recurrence from ~70–80% to less than 5%.

Question 346: A cat is accidentally administered a dose of acetaminophen (paracetamol). Which clinical sign is most characteristic of this specific toxicity in felines due to their metabolic differences?

Severe gastrointestinal ulceration
Methemoglobinemia and facial edema (Correct answer)
Acute fulminant hepatic necrosis
Profound coagulopathy

Correct answer: Methemoglobinemia and facial edema

Cats have a deficiency in the glucuronidation pathway, a major route for acetaminophen metabolism in other species. This shunts metabolism down alternative pathways, leading to the production of toxic metabolites that cause oxidative damage to red blood cells. This results in the formation of methemoglobin, which cannot carry oxygen, leading to cyanosis (often described as 'muddy' or brown mucous membranes), dyspnea, and often concurrent facial or paw edema. While liver damage can occur, methemoglobinemia is the more prominent and life-threatening feature in cats.

Question 347: A 7-year-old horse undergoing colic surgery develops hypotension (MAP 45 mmHg) unresponsive to IV fluid boluses. The anesthetist adds dobutamine at 3 mcg/kg/min with minimal improvement. Which pharmacologic intervention is MOST appropriate as the next step?

Administer phenylephrine at 1–2 mcg/kg/min
Switch to vasopressin at 0.5 mU/kg/min
Increase dobutamine to 10 mcg/kg/min
Add norepinephrine at 0.1–0.5 mcg/kg/min (Correct answer)

Correct answer: Add norepinephrine at 0.1–0.5 mcg/kg/min

Inhalant anesthesia (isoflurane/sevoflurane) in horses causes significant vasodilation and myocardial depression. When dobutamine (a β1/β2 agonist that increases cardiac output but causes vasodilation) is insufficient, norepinephrine is the drug of choice because it provides both α1-mediated vasoconstriction (increases SVR) and β1 inotropic support. Phenylephrine is a pure α1 agonist that raises SVR but can cause reflex bradycardia and reduced cardiac output—problematic in an already-compromised patient. Vasopressin can be used in refractory cases but is not typically a second-line agent. Escalating dobutamine alone will worsen vasodilation.

Question 348: Feline leukemia virus (FeLV) is classified into subtypes based on host range. Which subtype is associated with the most rapid disease progression and immunosuppression?

FeLV-A
FeLV-B
FeLV-T (Correct answer)
FeLV-C

Correct answer: FeLV-T

FeLV-T is highly pathogenic, targets T lymphocytes directly causing profound lymphopenia and accelerated immunodeficiency.

Question 349: A 7-year-old male neutered Labrador Retriever presents with a 3-week history of progressive tetraparesis. MRI of the cervical spine reveals a T2-hyperintense, T1-isointense intramedullary lesion at C4-C5 that does not enhance with gadolinium contrast. The lesion has a 'flame-shaped' appearance on sagittal sequences. Which diagnosis is MOST consistent with these imaging findings?

Spinal cord infarction (fibrocartilaginous embolism) (Correct answer)
Syringomyelia
Intramedullary astrocytoma
Intramedullary meningioma

Correct answer: Spinal cord infarction (fibrocartilaginous embolism)

Spinal cord infarction (fibrocartilaginous embolism, FCE) classically appears as a T2-hyperintense, T1-isointense intramedullary lesion with a characteristic 'flame-shaped' or wedge-shaped appearance on sagittal MRI sequences. Crucially, FCE lesions do NOT enhance with gadolinium because there is no disruption of the blood-brain barrier by a mass—this distinguishes them from most intramedullary tumors. Syringomyelia appears as a fluid-filled cavity (CSF-isointense on all sequences). Astrocytomas and meningiomas typically show some degree of contrast enhancement.

Question 350: A cattle producer wants to treat a cow with bacterial pneumonia. Which beta-lactam antibiotic has an approved long-acting formulation for cattle?

Amoxicillin
Penicillin G procaine
Ampicillin
Ceftiofur (Correct answer)

Correct answer: Ceftiofur

Ceftiofur (as ceftiofur crystalline free acid) has a long-acting formulation approved in cattle that provides therapeutic concentrations for several days.

Question 351: A 4-year-old spayed female cat tests positive on an ELISA for FeLV p27 antigen. She is clinically healthy. A proviral PCR on peripheral blood leukocytes is also positive, but a repeat ELISA 12 weeks later is negative, and a subsequent proviral PCR on bone marrow is negative. What is the MOST accurate classification of this cat's infection status, and what is the recommended management?

The cat experienced a regressive (previously called 'abortive' or 'latent') FeLV infection; proviral DNA is absent from bone marrow, indicating viral clearance; she is likely not infectious and can be managed as a healthy cat with periodic monitoring. (Correct answer)
The cat has a progressive infection with bone marrow sequestration of virus; the negative bone marrow PCR is a false negative due to low viral load, and she should be treated with antiviral therapy immediately.
The cat has a focal/compartmentalized infection limited to the mammary gland and salivary glands; she remains infectious via grooming despite the negative bone marrow PCR.
Discordant ELISA results indicate a defective ELISA assay; a Western blot for gp70 envelope protein is needed to confirm progressive infection before any management decisions.

Correct answer: The cat experienced a regressive (previously called 'abortive' or 'latent') FeLV infection; proviral DNA is absent from bone marrow, indicating viral clearance; she is likely not infectious and can be managed as a healthy cat with periodic monitoring.

FeLV infection outcomes include progressive infection (persistent antigenemia, high viral load, immunosuppression) and regressive infection (transient antigenemia that resolves, with proviral DNA integrated but not actively replicating—detectable in blood but not bone marrow). A cat with an initial positive ELISA that reverts to negative, combined with negative bone marrow proviral PCR, has most likely achieved regressive infection with viral clearance. These cats are generally not infectious, have a near-normal life expectancy, and do not require antiviral treatment—only periodic wellness monitoring. Focal/compartmentalized infection is a separate category involving persistent antigen in specific tissues despite negative blood tests.

Question 352: A 9-year-old Cairn Terrier has chronic hepatitis with copper accumulation on liver biopsy (>2000 µg/g dry weight). Which chelation agent is most commonly used in dogs to reduce hepatic copper?

EDTA
D-penicillamine (Correct answer)
Deferoxamine
Deferasirox

Correct answer: D-penicillamine

D-penicillamine is the most widely used copper chelator in dogs with copper-associated hepatopathy, mobilizing hepatic copper for urinary excretion.

Question 353: A dairy herd is experiencing an elevated somatic cell count (SCC) averaging 400,000 cells/mL. Which organism is most commonly associated with contagious mastitis causing elevated bulk tank SCC?

Staphylococcus aureus (Correct answer)
Streptococcus uberis
Klebsiella pneumoniae
Escherichia coli

Correct answer: Staphylococcus aureus

Staphylococcus aureus is the classic contagious mastitis pathogen spread cow-to-cow during milking, and is the leading cause of elevated bulk tank SCC in dairy herds.

Question 354: A veterinarian is performing a complete blood count on a red-tailed hawk (Buteo jamaicensis) and notices large, round, pale-staining intracytoplasmic inclusions within erythrocytes, affecting approximately 15% of cells. The bird is mildly lethargic but otherwise clinically stable. Which of the following is the MOST accurate statement regarding this finding?

These inclusions represent viral intranuclear inclusions displaced to the cytoplasm during erythrocyte maturation
This is Haemoproteus sp. and is considered non-pathogenic in raptors; treatment is unnecessary
This is Plasmodium sp., which is the primary avian malaria parasite requiring immediate chloroquine treatment
This is Leucocytozoon sp., which is transmitted by blackflies and can cause fatal anemia in accipiters (Correct answer)

Correct answer: This is Leucocytozoon sp., which is transmitted by blackflies and can cause fatal anemia in accipiters

The large, round intracytoplasmic inclusions in erythrocytes of a raptor are most consistent with Leucocytozoon sp. gametocytes. Unlike Haemoproteus (which has halter-shaped gametocytes in erythrocytes and is generally non-pathogenic), Leucocytozoon can cause severe hemolytic anemia, particularly in accipiters (Accipiter spp.) and young birds. It is transmitted by Simulium (blackflies) and Culicoides. Plasmodium produces smaller, irregular inclusions with hemozoin pigment granules. Leucocytozoon gametocytes are large enough to distort the host cell, which helps distinguish them.

Question 355: FIP has no known treatment.

True (Correct answer)
False

Correct answer: True

Historically, Feline Infectious Peritonitis (FIP) was considered an untreatable and universally fatal disease. While new antiviral drugs have emerged, at the time this question was likely formulated, there was no widely recognized or approved 'cure' or treatment. The statement reflects the historical understanding and the challenge of FIP treatment.

Question 356: Methicillin-resistant Staphylococcus aureus (MRSA) has been identified as an occupational zoonosis. Which livestock species is most closely linked to the LA-MRSA (livestock-associated MRSA) ST398 strain?

Dairy cattle
Poultry
Swine (Correct answer)
Small ruminants

Correct answer: Swine

LA-MRSA ST398 is strongly associated with swine and pig farm workers, representing a major veterinary public health concern.

Question 357: During a routine equine breeding soundness evaluation (BSE) in a 4-year-old Thoroughbred stallion, semen evaluation reveals: total motility 65%, progressive motility 45%, morphology 55% normal sperm. Per AAEP guidelines, how should this stallion be classified?

Satisfactory potential breeder
Questionable potential breeder (Correct answer)
Unsatisfactory potential breeder
Deferred — repeat evaluation in 30 days

Correct answer: Questionable potential breeder

AAEP minimum standards for a satisfactory equine BSE are: total motility ≥60%, progressive motility ≥60%, normal morphology ≥60%. This stallion fails progressive motility (45% vs. ≥60% required) and morphology (55% vs. ≥60% required), placing him in the 'questionable' category — not outright unsatisfactory, which requires multiple parameters clearly below threshold.

Question 358: During fluoroscopic esophagram in a 2-year-old German Shepherd, liquid barium rapidly opacifies the esophagus but you observe persistent, focal retention of barium in a fusiform dilation of the esophagus at the level of the heart base. The esophagus proximal and distal to this region is normal in caliber. Manometric data (if available) would MOST likely show which of the following?

Failure of lower esophageal sphincter relaxation (achalasia-like) (Correct answer)
Absent peristalsis throughout the entire esophagus
Reduced amplitude contractions in the caudal esophageal segment only
Normal esophageal peristalsis with elevated resting lower esophageal sphincter pressure

Correct answer: Failure of lower esophageal sphincter relaxation (achalasia-like)

Focal, persistent barium retention in a fusiform dilation at the heart base, with normal esophageal caliber proximal and distal, is the classic fluoroscopic appearance of a vascular ring anomaly—specifically persistent right aortic arch (PRAA) with entrapment of the esophagus. However, in an adult dog with acquired focal heart-base dilation, the most likely diagnosis is a functional obstruction analogous to achalasia (failure of the lower esophageal sphincter or distal esophageal segment to relax). This would produce failure of LES relaxation on manometry. True idiopathic megaesophagus shows absent peristalsis throughout the entire esophagus (choice B), not focal dilation. Choices C and D do not correspond to a mechanism that produces focal fusiform retention.

Question 359: A veterinarian is assessing a feedlot for bovine respiratory disease (BRD). Which scoring system is most widely used to objectively evaluate respiratory signs in individual cattle at the pen level?

Body condition scoring (BCS)
FAMACHA scoring system
Bovine Respiratory Disease Scoring System (BRDS) by McGuirk (Correct answer)
California Mastitis Test (CMT) adaptation for BRD

Correct answer: Bovine Respiratory Disease Scoring System (BRDS) by McGuirk

The McGuirk Bovine Respiratory Disease Scoring System evaluates rectal temperature, nasal discharge, eye discharge, ear position, and head carriage to provide an objective BRD score for pull decisions.

Question 360: Which Doppler modality provides a color-coded two-dimensional map of blood flow direction and velocity within a vessel or cardiac chamber?

Power Doppler
Color flow Doppler (Correct answer)
Pulsed wave Doppler
Continuous wave Doppler

Correct answer: Color flow Doppler

Color flow Doppler superimposes a color-coded map of mean flow velocity and direction over the B-mode image, using red/blue by convention for flow toward/away from the transducer.

NAVLE (North American Veterinary Licensing Exam)

The NAVLE (North American Veterinary Licensing Exam) exam validates essential knowledge and skills required for certification or licensure in this field.

360

Questions

420 min

Time Limit

65%

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