Laboratory Procedures
Sample collection and handling
Sorted by tube color: EDTA (lavender) for CBC, heparin (green) for plasma chemistry, serum separator (red/gold) for serum chemistry, citrate (blue) for coagulation, and oxalate/fluoride (gray) for glucose. Fill tubes to the marked line, mix by gentle inversion, and follow the order of draw. Deliver samples promptly; lipemia, hemolysis, and delayed processing all distort results, and EDTA can create platelet clumping that mimics thrombocytopenia.
Hematology
Manual PCV and total protein remain core skills: fill a microhematocrit tube, seal, spin, and read the packed cell volume against the scale, then read the plasma protein with a refractometer. Note plasma color (icterus, hemolysis, lipemia) and buffy coat size. On a stained smear, examine the feathered edge and monolayer; estimate platelets at roughly 15,000–20,000/µL per platelet seen per oil-immersion field.
Urinalysis, feces, and cytology
Cystocentesis is preferred for culture because it avoids contamination. Specific gravity is measured by refractometer, not dipstick; dipsticks give chemistry, and sediment exam identifies crystals, cells, and casts. Fecal flotation with centrifugation recovers eggs more reliably than simple standing flotation. Cytology evaluates cell type and inflammation.
Worked example
A dog's smear shows an average of 2 platelets per oil-immersion field: estimated platelet count is about 30,000–40,000/µL - a genuine thrombocytopenia worth reporting, provided clumping is absent.
Traps
Reading specific gravity from a dipstick pad, refrigerating a CBC sample, under-filling citrate tubes, and interpreting hemolyzed chemistry values as real disease.