VTNE Clinical Laboratory Procedures Questions and Answers — Questions and Answers
Question 1: A complete blood count (CBC) from an anemic dog is analyzed. Which finding on a Wright-Giemsa stained blood smear is the most definitive indicator of a regenerative bone marrow response?
- Presence of spherocytes
- Significant polychromasia (Correct answer)
- Numerous target cells (codocytes)
- Occasional Howell-Jolly bodies
Correct answer: Significant polychromasia
Polychromasia, the presence of bluish-red, larger-than-normal erythrocytes, is the hallmark of a regenerative anemia on a Wright-Giemsa smear. These cells are reticulocytes (immature red blood cells) that have been released early from the bone marrow to compensate for the anemia. Spherocytes suggest immune-mediated hemolysis, target cells can be seen in various conditions, and Howell-Jolly bodies are nuclear remnants that can be present in both regenerative and non-regenerative states.
Question 2: A veterinary technician examines a urine sediment sample from a 7-year-old male Dalmatian and observes numerous flat, six-sided, colorless crystals. This finding is most consistent with which type of crystal?
- Struvite
- Calcium Oxalate Dihydrate
- Uric Acid (Correct answer)
- Calcium Carbonate
Correct answer: Uric Acid
Dalmatians have a genetic defect in purine metabolism that leads to increased excretion of uric acid in their urine. This predisposes them to the formation of uric acid crystals and uroliths, which are characteristically diamond, rhomboid, or six-sided (hexagonal) plates.
Question 3: Which of the following serum chemistry tests is considered the most specific indicator of hepatocellular (liver cell) damage in dogs and cats?
- Alkaline Phosphatase (ALP)
- Alanine Aminotransferase (ALT) (Correct answer)
- Blood Urea Nitrogen (BUN)
- Total Bilirubin
Correct answer: Alanine Aminotransferase (ALT)
Alanine Aminotransferase (ALT) is a leakage enzyme found in high concentrations within the cytoplasm of hepatocytes. When liver cells are damaged, ALT leaks into the bloodstream, making it a sensitive and specific indicator of hepatocellular injury in small animals. While ALP can indicate liver issues, it is more related to cholestasis and can be elevated for other reasons (e.g., bone growth, steroid use). BUN is a marker of kidney function and protein metabolism, and Total Bilirubin indicates issues with bile flow or hemolysis.
Question 4: A technician is performing a Gram stain on a sample from an ear swab. After applying the crystal violet and iodine, they accidentally rinse the slide with the alcohol decolorizer for too long. How will this error most likely affect the appearance of Gram-positive bacteria on the slide?
- They will appear purple, as expected.
- They will form chains instead of clusters.
- They will appear pink or red. (Correct answer)
- They will be completely washed off the slide.
Correct answer: They will appear pink or red.
The alcohol step is the decolorizer. Over-decolorizing, or rinsing with alcohol for too long, can strip the crystal violet-iodine complex even from the thick peptidoglycan layer of Gram-positive bacteria. This causes them to lose the primary purple stain, and they will then take up the safranin counterstain, making them incorrectly appear pink or red, like Gram-negative bacteria.
Question 5: When performing a fecal flotation, which of the following solutions is commonly used because its specific gravity allows most common parasite eggs to float while causing heavier debris to sink?
- Distilled water
- Sodium Nitrate (Correct answer)
- 70% Isopropyl alcohol
- Sodium hypochlorite
Correct answer: Sodium Nitrate
Fecal flotation solutions, such as sodium nitrate, zinc sulfate, or sugar solutions, are designed to have a specific gravity (typically 1.18-1.27) that is higher than that of most parasite ova but lower than that of fecal debris. This density difference allows the eggs to float to the surface for collection and identification. Distilled water is not dense enough, and alcohol and hypochlorite are not used for this purpose.
Question 6: A veterinary technician uses a handheld refractometer to measure a patient's urine specific gravity. What is the underlying physical principle that allows this instrument to provide a measurement?
- The absorption of specific light wavelengths by solutes.
- The electrical impedance created as cells pass through an aperture.
- The scattering of a light beam by suspended particles.
- The bending of light as it passes through a fluid containing dissolved solids. (Correct answer)
Correct answer: The bending of light as it passes through a fluid containing dissolved solids.
A refractometer operates on the principle of light refraction. It measures the angle at which light bends as it passes from the air through the liquid sample (the refractive index). The concentration of dissolved solids in the fluid (like solutes in urine or proteins in plasma) determines the degree of this bending. The instrument's scale is calibrated to correlate this angle of refraction to a specific gravity or total protein value.
VTNE Clinical Laboratory Procedures Questions and Answers
A complete blood count (CBC) from an anemic dog is analyzed.
Which finding on a Wright-Giemsa stained blood smear is the most definitive indicator of a regenerative bone marrow response?