Impact of preheparinization and sample volume on routine hematology findings in healthy cats.

OBJECTIVES

It can be challenging to collect sufficient blood from feline patients for both a biochemical profile and a complete blood count (CBC). The ability to generate accurate hematologic and biochemical data from a single, small (<2 ml) sample could reduce patient stress and improve clinical efficiency. The objective of this study was to determine the impact of preheparinization and/or sample size on routine hematology findings in cats.

METHODS

Blood was collected from 20 healthy cats; measured aliquots were placed directly into tubes containing either EDTA or lithium-heparin (Hep). Within 2 mins, specific volumes were removed from the Hep tubes and placed in additional EDTA tubes. Four distinct sample sizes/types were created from each cat: (1) 1.3 ml EDTA (criterion standard); (2) 0.5 ml EDTA; (3) 1.3 ml Hep + EDTA; and (4) 0.5 ml Hep + EDTA. Three CBCs were performed on each sample using an automated bench-top hematology analyzer. Drops of blood were contemporaneously used to create three air-dried stained slides from each tube. Triplicate results were averaged for statistical analysis; results were compared across all sample types and against the criterion standard. Significance was set at <0.05.

RESULTS

Preheparinization did not significantly impact determinations of erythrocyte number, hematocrit, hemoglobin concentration, mean cell volume and neutrophil count. Platelet counts for the non-traditional samples correlated poorly with the criterion standard, although numbers could be effectively estimated using stained slides. Cell morphology was well preserved across all sample types.

CONCLUSIONS AND RELEVANCE

These results indicate that a 0.5 ml preheparinized EDTA blood sample can generate clinically useful hematologic data (excluding platelet count) in cats, using a bench-top analyzer. Our findings support the collection of a single small (<2 ml) sample that can be used for both biochemical and hematologic analyses. Further studies are needed to verify these findings using other hematology machines and in diseased cats.