NAVLE General Practice 4

Question 1

A 7-year-old intact male Labrador Retriever presents with a 3-day history of polyuria, polydipsia, and a purulent penile discharge. Physical exam reveals a fluctuant abdominal mass caudal to the umbilicus. Abdominal ultrasound shows a fluid-filled uterus-like structure. Which of the following best explains this finding?

Accepted Answer

Retained Müllerian duct remnant (persistent Müllerian duct syndrome) with secondary infection

Answer

Persistent Müllerian duct syndrome (PMDS) occurs in male dogs when Müllerian-inhibiting substance (MIS/AMH) fails to cause regression of the paramesonephric ducts, resulting in a uterus-like structure (uterus masculinus). Miniature Schnauzers are most commonly affected, but it can occur in any breed. The structure can develop pyometra-like infections in intact males, explaining the purulent discharge and systemic signs. Prostatic disease is a common differential but would not produce a distinct fluid-filled midline uterus-like structure separate from the prostate on ultrasound.

Question 2

A 4-year-old spayed female Doberman Pinscher is presented for a pre-breeding cardiac clearance (owner is unaware she is spayed). Auscultation reveals a soft, grade II/VI left apical systolic murmur. Echo shows mild left ventricular dilation with an ejection fraction of 48%. Which statement most accurately describes the appropriate management and genetic counseling?

Accepted Answer

No treatment indicated; repeat echo in 6 months, and inform the owner the dog is spayed before discussing breeding

Answer

The dog has pre-clinical dilated cardiomyopathy (DCM), which is common in Doberman Pinschers. Current evidence (PROTECT study) supports pimobendan initiation when occult DCM is confirmed by echo criteria (LVIDd >46mm or LVIDs >38mm in females, or EF <50%). However, the immediate priority in the clinical scenario is to address the factual error — the dog is spayed and cannot be bred. Pimobendan would be appropriate once DCM criteria are confirmed, but answering the counseling question requires first correcting the owner's misunderstanding. Enalapril alone is not first-line for pre-clinical DCM in Dobermans.

Question 3

A 6-month-old intact female Border Collie is presented with a 2-week history of progressive hindlimb ataxia, hypermetria, and intention tremors. The puppy was purchased from a farm where the dam was fed a selenium-deficient diet during gestation. Cerebrospinal fluid analysis is unremarkable. Which diagnosis is most consistent with these findings?

Accepted Answer

Neuroaxonal dystrophy (NAD) specific to Border Collies

Answer

Neuroaxonal dystrophy (NAD) is a hereditary neurodegenerative condition recognized in Border Collies caused by mutations in the PLA2G6 gene. It presents in young dogs (typically 2–6 months) with progressive cerebellar signs including ataxia, hypermetria, and intention tremors. CSF is often normal. While selenium deficiency can cause white muscle disease (skeletal and cardiac muscle necrosis) in young animals, it does not cause cerebellar hypoplasia in dogs. Canine distemper causes cerebellar hypoplasia in neonatal infection but would typically have other systemic signs. The breed-specific hereditary condition is the most accurate diagnosis here.

Question 4

A 10-year-old domestic shorthair cat is being managed for hyperthyroidism with methimazole. Two weeks after starting therapy, the owner reports the cat is now eating less, has facial pruritus, and has developed excoriations around the face and neck. Blood work shows: BUN 58 mg/dL, creatinine 3.1 mg/dL, and phosphorus 6.8 mg/dL — values that were within normal limits prior to treatment. Which is the best next step?

Accepted Answer

Discontinue methimazole temporarily, re-evaluate renal values, and consider dose reduction or alternative therapy based on clinical and lab reassessment

Answer

This cat has two concurrent problems: methimazole-induced facial pruritus (a known idiosyncratic adverse effect in ~2% of cats, typically within the first 4 weeks) and unmasked chronic kidney disease (CKD). Hyperthyroidism raises GFR, masking underlying CKD; successful treatment lowers GFR and reveals pre-existing renal disease. The facial pruritus with excoriations is a cutaneous drug reaction requiring methimazole discontinuation. After stopping methimazole and allowing thyroid status to normalize, renal values should be reassessed. If CKD is confirmed, the risk-benefit of treating hyperthyroidism must be individualized — sometimes a lower target T4 or alternative therapy (radioiodine at a lower dose) is chosen. Continuing methimazole despite a drug reaction would be inappropriate.

Question 5

A 3-year-old Quarter Horse mare is presented with a history of recurrent episodes of mild colic, weight loss despite a good appetite, and loose feces. Fecal egg count is 0 EPG. Serum chemistry reveals hypoalbuminemia (2.1 g/dL) and elevated beta-globulins. Rectal palpation reveals thickened large colon walls. Which condition is highest on the differential list?

Accepted Answer

Cyathostominosis (larval cyathostomiasis) with mucosal larval emergence

Answer

Larval cyathostomiasis (Type II cyathostominosis) occurs when large numbers of encysted early third-stage (EL3) cyathostomin larvae simultaneously emerge from the intestinal mucosa, causing protein-losing enteropathy, diarrhea, weight loss, and colic. Critically, adult egg-shedding larvae are absent during this phase, so fecal egg counts are zero or very low — this is a key distinguishing feature. Hypoalbuminemia and elevated beta-globulins reflect the protein loss and acute-phase response. Thickened colon walls on rectal palpation support mucosal infiltration. Equine proliferative enteropathy (Lawsonia) is seen primarily in weanlings and yearlings. Right dorsal colitis would have a history of NSAID use. MEED is rare and typically involves multiple organ systems.

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE General Practice 4