CVA Laboratory Techniques and Diagnostic Procedures 2 — Questions and Answers
Question 1: What is the principle behind a fecal flotation test?
- Parasites are attracted to the solution chemically
- Parasite eggs float in a high-density solution while debris sinks, concentrating eggs at the surface (Correct answer)
- The solution kills parasites for naked-eye viewing
- Flotation separates bacteria types
Correct answer: Parasite eggs float in a high-density solution while debris sinks, concentrating eggs at the surface
Fecal flotation uses a solution denser than parasite eggs but lighter than most debris, causing eggs to float for microscopic identification.
Centrifugal flotation is more sensitive than passive flotation. A coverslip placed on the surface collects floating eggs. Eggs are identified by their size, shape, color, and internal structure.
Question 2: What does a refractometer measure with urine, and what is normal for dogs?
- Urine pH, normal 6.0-7.0
- Urine specific gravity (concentration), normal 1.015-1.045 (Correct answer)
- Protein content, normal less than 10 mg/dL
- Glucose concentration, normal 0 mg/dL
Correct answer: Urine specific gravity (concentration), normal 1.015-1.045
A refractometer measures urine specific gravity by determining how light bends, reflecting solute concentration. Normal for dogs is 1.015-1.045.
USG below 1.008 is hyposthenuric, 1.008-1.012 is isosthenuric (impaired concentrating ability). The refractometer should be calibrated daily with distilled water reading 1.000.
Question 3: What is the purpose of Romanowsky-type staining (Diff-Quik or Wright's) of blood smears?
- To kill infectious organisms
- To differentially color cellular components for microscopic identification of cell types (Correct answer)
- To preserve the smear for storage
- To make red blood cells larger
Correct answer: To differentially color cellular components for microscopic identification of cell types
Romanowsky stains use acidic and basic dyes that differentially color nuclei purple/blue and cytoplasm pink/blue, enabling cell identification.
Diff-Quik is the rapid version using 3 dips: fixative, eosin, and methylene blue. This allows identification of neutrophils, lymphocytes, monocytes, eosinophils, basophils, and abnormal cells.
Question 4: What organ systems does a serum chemistry panel evaluate?
- Only white blood cell counts
- Liver enzymes, kidney values, electrolytes, glucose, and proteins to assess organ function (Correct answer)
- Blood type compatibility
- Only cholesterol and triglycerides
Correct answer: Liver enzymes, kidney values, electrolytes, glucose, and proteins to assess organ function
A chemistry panel measures analytes reflecting liver (ALT, ALP), kidney (BUN, creatinine), pancreas (lipase), and metabolic status (glucose, electrolytes).
Liver markers: ALT, ALP, GGT, bilirubin. Kidney markers: BUN, creatinine, SDMA. Pancreas: lipase, glucose. Chemistry panels are run on serum or heparinized plasma after centrifugation.
Question 5: What does a positive heartworm ELISA test detect?
- Heartworm larvae in blood
- Adult female heartworm antigen (Correct answer)
- Antibodies against heartworm
- Dead heartworm fragments in lungs
Correct answer: Adult female heartworm antigen
Most commercial tests detect glycoprotein antigen from adult female Dirofilaria immitis, detectable at least 6-7 months post-infection.
The test specifically detects adult females, so male-only infections can be false negative. Very low burdens may produce weak results. Heat treatment of the sample can improve sensitivity.
Question 6: What do epithelial cell casts in urine sediment indicate?
- Normal finding
- Damage or disease affecting the renal tubular epithelium (Correct answer)
- Confirmed urinary tract infection
- Only found in contaminated samples
Correct answer: Damage or disease affecting the renal tubular epithelium
Epithelial cell casts form when renal tubular cells are incorporated into protein matrix within the tubular lumen, indicating active tubular damage.
Causes include nephrotoxins, ischemia, or acute tubular necrosis. Other cast types: hyaline (protein only), granular (degenerated cellular), waxy (advanced degeneration), RBC casts (glomerulonephritis).
CVA Laboratory Techniques and Diagnostic Procedures 2
What is the principle behind a fecal flotation test?