Mixed Deck — All NAVLE Topics Flashcards

A 2-year-old female Weimaraner presents with recurrent urinary tract infections despite appropriate antibiotic therapy. Vaginal examination reveals a band of tissue at the vestibulovaginal junction. What is the likely diagnosis?

Answer: Vestibulovaginal stenosis (vaginal stricture)

Vestibulovaginal stenosis creates a pool of urine anterior to the stricture that acts as a reservoir for bacterial colonization, causing recurrent UTIs.

A 7-year-old Labrador Retriever presents with progressive hindlimb paresis. MRI of the thoracolumbar spine reveals a T2-hyperintense, T1-isointense intradural-extramedullary mass at T10-T11 that shows homogeneous contrast enhancement. The most likely diagnosis is:

Answer: Meningioma

Meningiomas are the most common intradural-extramedullary spinal tumors in dogs. Their MRI characteristics include T2 hyperintensity, T1 isointensity relative to spinal cord, homogeneous contrast enhancement, and a 'dural tail' sign. They are extramedullary (outside the cord but inside the dura), distinguishing them from intramedullary tumors like astrocytomas. Nerve sheath tumors are also intradural-extramedullary but more commonly affect nerve roots and show heterogeneous enhancement. Nephroblastoma occurs in the spinal cord of young dogs but is intramedullary.

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?

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.

Intra-articular injection of which substance is used as a visco-supplementation therapy to improve synovial fluid quality in horses with joint disease?

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.

Which of the following best describes the mechanism by which FeLV causes non-regenerative anemia in some infected cats?

Answer: Direct viral infection of erythroid precursors in bone marrow causing myelosuppression

FeLV directly infects erythroid progenitor cells in the bone marrow, impairing red blood cell production and causing non-regenerative anemia.

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

Answer: Lymphoma

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

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?

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.

A 6-year-old neutered male mixed-breed dog is presented for polydipsia, polyuria, and muscle weakness. Serum chemistry reveals sodium 158 mEq/L, potassium 2.8 mEq/L, and bicarbonate 30 mEq/L. Blood pressure is 178/110 mmHg. Urine aldosterone-to-creatinine ratio is markedly elevated. An adrenal mass (2.1 cm) is identified on ultrasound. Cortisol concentrations pre- and post-ACTH stimulation are within normal limits. What is the most appropriate next diagnostic step?

Answer: CT scan of the abdomen to evaluate for vascular invasion and characterize the mass

This presentation is classic for primary hyperaldosteronism (Conn's syndrome) in a dog — hypertension, hypokalemia, hypernatremia, metabolic alkalosis, and an adrenal mass with normal cortisol dynamics. Once primary hyperaldosteronism is biochemically confirmed (elevated aldosterone:creatinine), the critical next step before surgical adrenalectomy is CT imaging to assess mass characteristics, identify vascular invasion, detect contralateral adrenal involvement, and rule out metastatic disease — all of which dictate surgical candidacy and prognosis. Plasma renin activity is useful but not the most actionable immediate next step given that surgical planning takes priority.

During a routine physical exam, a 4-month-old Bulldog puppy is noted to have a heart murmur. Echocardiography reveals obstruction of the right ventricular outflow tract and right ventricular hypertrophy. What is the definitive therapy?

Answer: Balloon valvuloplasty via cardiac catheterization

Balloon valvuloplasty is the treatment of choice for pulmonic stenosis in dogs, providing effective relief of the outflow obstruction with low morbidity.

A 3-year-old intact female rabbit is anesthetized for an ovariohysterectomy. Forty minutes into maintenance on 2.5% isoflurane, the rabbit becomes apneic with no response to a sternal rub. SpO2 drops to 82%. Which factor is MOST responsible for this rabbit's increased anesthetic risk compared to dogs and cats?

Answer: Rabbits have obligate nasal breathing and a relatively small thoracic cavity with diaphragm-dependent ventilation

Rabbits are obligate nasal breathers with a diaphragm-dependent respiratory pattern and a relatively large abdominal visceral mass that restricts diaphragmatic excursion in dorsal recumbency. They have a narrow thoracic cavity relative to body size, poor respiratory reserve, and a highly sensitive respiratory center that is easily depressed by inhalants. These anatomical features make apnea common at surgical planes of anesthesia and make ventilatory support mandatory. The rabbit MAC for isoflurane (~2.05%) is indeed slightly higher than in dogs (~1.28%) and cats (~1.63%), but this alone doesn't cause apnea at 2.5%. Rabbits do have µ-opioid receptors. While high metabolic rate is real, it does not cause apnea.

When designing a biosecurity protocol for a cow-calf operation, which practice is MOST important for preventing introduction of Bovine Leukemia Virus (BLV)?

Answer: Testing all purchased cattle for BLV antibodies before introduction and segregating positives

BLV is most effectively prevented by serological testing (AGID or ELISA) of all purchased cattle and excluding seropositive animals, since there is no approved vaccine in the US.

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?

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.

A rabbit (Oryctolagus cuniculus) is presented for acute anorexia and abdominal distension. On physical exam, there is tympany in the cecal region, hypothermia (98.4°F), and the cecum is palpably enlarged and doughy. Radiographs confirm massive cecal dilation with a gas cap. The rabbit has been on a high-pellet, low-hay diet. Which statement MOST accurately describes the pathophysiology of cecal dysbiosis in this patient?

Answer: Excess simple carbohydrates shift cecal pH toward alkaline conditions, favoring Clostridium spiroforme overgrowth and iota-toxin production

In rabbits, cecal dysbiosis (often called rabbit enterotoxemia or mucoid enteropathy complex) is precipitated by excess fermentable carbohydrates reaching the cecum. This substrate shift favors proliferation of Clostridium spiroforme, which produces iota-toxin (a binary toxin similar to Clostridium perfringens iota-toxin). The normal cecal pH is mildly acidic (5.9–6.8); carbohydrate overload and disrupted VFA production raise the pH, creating an environment favorable for clostridial overgrowth. Iota-toxin disrupts actin cytoskeleton of enterocytes, causing fluid secretion, mucosal damage, and the classic cecal dilation and tympany seen here. The condition carries a guarded to poor prognosis.

Which antifungal drug is currently the first-line treatment for aspergillosis in birds?

Answer: Voriconazole

Voriconazole is the preferred antifungal for avian aspergillosis due to its superior efficacy and safety compared to older azoles.

During a pre-purchase exam of a 5-year-old Quarter Horse, grade 3/5 left forelimb lameness is localized to the foot with a palmar digital nerve block. Radiographs reveal navicular bone erosions and synovial invaginations. The diagnosis is:

Answer: Navicular syndrome (palmar foot pain)

Navicular syndrome is characterized by palmar foot pain, positive response to palmar digital nerve block, and radiographic changes including synovial fossae and flexor cortex erosions of the navicular bone.

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

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.

A dog is diagnosed with immune-mediated hemolytic anemia (IMHA). Which finding on the CBC is most specific for confirming immune-mediated destruction?

Answer: Spherocytosis on blood smear

Spherocytes, which lack the normal biconcave shape due to partial phagocytosis of antibody-coated membrane by macrophages, are the most specific morphologic finding for IMHA.

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?

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.

A ferret presents with progressive hind limb weakness, muscle wasting, and hypoglycemia. Blood glucose is 45 mg/dL. The most likely diagnosis is:

Answer: Insulinoma

Insulinoma is the most common pancreatic tumor in ferrets and classically causes episodic hypoglycemia with hind limb weakness.

A 5-year-old Beagle is presented with an acute abdomen and radiographs reveal a markedly distended stomach with gas and a 'double bubble' appearance. Which surgical procedure is performed to prevent recurrence after gastric decompression?

Answer: Gastropexy

Gastropexy permanently adheres the stomach to the right abdominal wall, preventing future rotation and recurrence of gastric dilatation-volvulus (GDV).