DVM Doctor of Veterinary Medicine Clinical Pathology and Diagnostics Questions and Answers — Questions and Answers
Question 1: A 3-year-old mixed-breed dog presents with lethargy and pale mucous membranes. A complete blood count (CBC) reveals a hematocrit of 18% (reference range 37-55%), with an absolute reticulocyte count of 350,000/µL (reference >80,000/µL indicates regeneration). Which of the following is the most accurate interpretation of this anemia?
- Non-regenerative, likely due to chronic kidney disease.
- Regenerative, likely due to hemorrhage or hemolysis. (Correct answer)
- Anemia of inflammatory disease.
- A laboratory error in the hematocrit measurement.
Correct answer: Regenerative, likely due to hemorrhage or hemolysis.
The markedly high absolute reticulocyte count indicates that the bone marrow is responding appropriately to the anemia by producing and releasing new red blood cells. This is the hallmark of a regenerative anemia, which is typically caused by red blood cell loss (hemorrhage) or destruction (hemolysis).
Question 2: A feline patient's chemistry panel shows a marked elevation in alanine aminotransferase (ALT) and aspartate aminotransferase (AST), with only a mild increase in alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT). This pattern is most indicative of what type of liver pathology?
- Post-hepatic biliary obstruction.
- Glucocorticoid-induced hepatopathy.
- Hepatocellular leakage or injury. (Correct answer)
- Cholestasis.
Correct answer: Hepatocellular leakage or injury.
ALT and AST are considered hepatocellular leakage enzymes because they are primarily located within the cytoplasm of hepatocytes. Significant elevations point towards direct damage or death of the liver cells, causing the enzymes to leak into the bloodstream. In contrast, ALP and GGT are primarily cholestatic enzymes, and their marked elevation would suggest a problem with bile flow.
Question 3: A 12-year-old cat is presented with polyuria and polydipsia. A chemistry panel reveals a blood urea nitrogen (BUN) of 85 mg/dL (reference 16-36 mg/dL) and creatinine of 4.2 mg/dL (reference 0.8-2.4 mg/dL). Which of the following urinalysis findings would most strongly support a diagnosis of primary renal failure?
- Urine specific gravity of 1.050.
- Urine pH of 6.0.
- 2+ bilirubin on the dipstick.
- Urine specific gravity of 1.010. (Correct answer)
Correct answer: Urine specific gravity of 1.010.
In the presence of significant azotemia (elevated BUN and creatinine), a healthy kidney should be maximally concentrating urine, resulting in a high specific gravity (typically >1.035 in a cat). A specific gravity in the isosthenuric range (1.008-1.012) indicates that the kidney tubules have lost their ability to concentrate or dilute urine, which is a hallmark of primary renal failure.
Question 4: A fine-needle aspirate is performed on a subcutaneous mass from a dog. Which of the following cytologic features is most definitive for a diagnosis of malignancy?
- A monomorphic population of well-differentiated cells.
- Significant neutrophilic inflammation with intracellular bacteria.
- The presence of prominent anisokaryosis and multiple, variably sized nucleoli. (Correct answer)
- Abundant hemodilution and low cellularity.
Correct answer: The presence of prominent anisokaryosis and multiple, variably sized nucleoli.
While inflammation can cause some reactive cellular changes, the presence of marked variation in nuclear size (anisokaryosis), and multiple, large, or variably shaped nucleoli are considered strong criteria of malignancy. These features suggest uncontrolled and abnormal cell division.
Question 5: A 10-year-old dog is found to have a total calcium level of 14.5 mg/dL (reference range 9.0-11.5 mg/dL). After confirming persistent ionized hypercalcemia, what is the most important next diagnostic test to investigate the most common cause of this finding in dogs?
- Abdominal ultrasound to check for adrenal tumors.
- Measurement of parathyroid hormone-related protein (PTHrP). (Correct answer)
- Thoracic radiographs to screen for fungal disease.
- A complete urinalysis to check for urolithiasis.
Correct answer: Measurement of parathyroid hormone-related protein (PTHrP).
The most common cause of severe hypercalcemia in dogs is humoral hypercalcemia of malignancy. Parathyroid hormone-related protein (PTHrP) is a substance secreted by certain tumors (most commonly lymphoma and anal sac adenocarcinoma) that mimics the action of PTH. Measuring PTHrP is a crucial step in diagnosing this common paraneoplastic syndrome.
Question 6: Which of the following classic sets of changes on a canine complete blood count (CBC) is most consistent with a 'stress leukogram' induced by endogenous or exogenous corticosteroids?
- Neutrophilia, lymphocytosis, eosinophilia, monocytosis.
- Neutropenia, lymphocytosis, eosinopenia, monocytopenia.
- Neutrophilia, lymphopenia, eosinopenia, monocytosis. (Correct answer)
- Neutropenia, lymphopenia, eosinophilia, monocytosis.
Correct answer: Neutrophilia, lymphopenia, eosinopenia, monocytosis.
A classic stress leukogram, caused by glucocorticoids (stress), is characterized by neutrophilia (mature neutrophils), lymphopenia, eosinopenia, and, in dogs, monocytosis. The most consistent findings are neutrophilia and lymphopenia.
DVM Doctor of Veterinary Medicine Clinical Pathology and Diagnostics Questions and Answers
A 3-year-old mixed-breed dog presents with lethargy and pale mucous membranes.
A complete blood count (CBC) reveals a hematocrit of 18% (reference range 37-55%), with an absolute reticulocyte count of 350,000/µL (reference >80,000/µL indicates regeneration).
Which of the following is the most accurate interpretation of this anemia?