NAVLE Feline Internal Medicine 3 — Questions and Answers
Question 1: A cat with chronic vomiting undergoes endoscopic biopsy showing diffuse infiltration of small lymphocytes in the lamina propria. PARR testing confirms clonality. Which diagnosis is confirmed?
- Inflammatory bowel disease
- Large cell lymphoma
- Small cell lymphoma (Correct answer)
- Mast cell tumor
Correct answer: Small cell lymphoma
Clonal small lymphocyte infiltration confirmed by PCR for antigen receptor rearrangement (PARR) distinguishes small cell lymphoma from IBD, which is polyclonal.
Question 2: Which urine specific gravity value is most consistent with isosthenuria in a cat with suspected chronic kidney disease?
- 1.005
- 1.012 (Correct answer)
- 1.025
- 1.040
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 3: A cat on long-term methimazole therapy for hyperthyroidism develops facial excoriation, pruritus, and jaundice. Which complication is most likely?
- Hypothyroidism
- Hepatotoxicity and immune-mediated dermatitis (Correct answer)
- Renal decompensation
- Thrombocytopenia
Correct answer: Hepatotoxicity and immune-mediated dermatitis
Methimazole can cause hepatotoxicity and facial pruritus/excoriation due to immune-mediated dermatitis, both reasons to consider alternative therapy such as radioiodine or surgery.
Question 4: 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
- Lymphoma (Correct answer)
- Hypervitaminosis D
Correct answer: Lymphoma
Lymphoma is the most common cause of hypercalcemia of malignancy in cats, mediated by PTHrP secretion.
Question 5: Which finding on echocardiography best differentiates hypertrophic cardiomyopathy (HCM) from physiologic cardiac hypertrophy secondary to hyperthyroidism in a cat?
- Left ventricular free wall thickness >6 mm
- Systolic anterior motion (SAM) of the mitral valve (Correct answer)
- Increased fractional shortening >45%
- Mild left atrial enlargement
Correct answer: Systolic anterior motion (SAM) of the mitral valve
SAM of the mitral valve causing dynamic left ventricular outflow tract obstruction is characteristic of primary HCM and is not a feature of hyperthyroid-induced hypertrophy.
Question 6: 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?
- Hyperaldosteronism (Conn's syndrome) (Correct answer)
- Addison's disease
- Hypothyroidism
- Pheochromocytoma
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 7: 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
- Serum bile acid pre/post prandial
- Rectal portal scintigraphy
- CT angiography (Correct answer)
Correct answer: CT angiography
CT angiography (computed tomographic angiography) provides precise anatomic delineation of shunt location and morphology, guiding surgical planning.
NAVLE Feline Internal Medicine 3
A cat with chronic vomiting undergoes endoscopic biopsy showing diffuse infiltration of small lymphocytes in the lamina propria.
PARR testing confirms clonality.
Which diagnosis is confirmed?