Overview Study of blood cells. Red cells via: White cells via: Platelets via: Uses Alone Most information can be gained from PCV (need RBC count if send to laboratory, because PCV may be falsely elevated if cells swell in post, ie MCV); WBC and differential WBC count; WBC and RBC morphology; platelet estimate and morphology. Anemia: PCV, reticulocyte count (aggregate count important in cats to determine whether regeneration is adequate or not), RBC count and morphology and Hb. Sampling Source of test material Quantity of test material 2.5 ml (0.5-1.0 ml minimum) whole blood (EDTA or citrated). Sample collection technique Standard. EDTA usually preferred for CBC, feline red cells shrink in the presence of excess concentrations of EDTA therefore correct volume is Hb. Citrate for activated partial thromboplastin time, one-stage prothrombin time and tissue thromboplastin (other clotting tests require specialized collection or immediate testing). Citrated sample may be useful for platelet counts if there is clumping with EDTA. Quality control Precautions Fill containers to correct level. Replace cap immediately to prevent evaporation. Mix correctly by gentle inversion several times. Slow blood collection may lead to clotting; rapid collection may lead to hemolysis. Timing of test Best after 12 hour fast (to avoid lipemia). Sample storage Refrigerate if analysis delayed but note that refrigeration often promotes platelet clumping which may interfere with platelet count. Make blood smear from freshly collected EDTA blood, submit with EDTA blood for CBC. Sample transport Ideally within 24 hours but standard mail adequate (12 hours or less for clotting times). Tests Availability Widely available at commercial laboratories. Blood smears can be examined in practice. Some in-hospital analyzers or cell counting methods now available. Validity Sensitivity Generally moderate to low unless blood parasites are recognized. Specificity Generally moderate to low unless blood parasites are recognized. Result Data Abnormal values Results may be diagnostic on their own or will rule out some differential diagnoses, or they will complement other laboratory tests. Errors and artifacts Poor sample handling: Clotting makes sample unsuitable for evaluation. Hemolysis will affect RBC indices. Further Reading Publications Refereed papers Other sources of information Cowell R L, Tyler R D & Meinkoth J H (1999) Diagnostic Cytology and Hematology of the Dog and Cat. 2nd edn. Mosby, USA. Duncan J R, Prasse K W & Mahaffey E A (1994) Veterinary Laboratory Medicine. Clinical Pathology. 3rd edn. Iowa University Press, USA Jain N C (1993) Essentials of Veterinary Haematology. Lea & Febiger, USA.