In vitro effect of Altered Platelet Count on Multiple Electrode Impedance Aggregometry in Dogs

Abstract

The objective of this study was to assess platelet aggregation by impedance aggregometry using canine whole blood with adjusted platelet counts. Citrated venous samples from 24 healthy dogs were aliquoted into unmanipulated and manipulated fractions with progressively depleted platelet counts to yield 2-3 samples per subject. All samples were corrected to native hematocrit (Hct) within 2% and cell counts performed before undergoing aggregation using a Multiplate® analyzer. Aggregation was initiated in all samples by addition of the platelet agonist adenosine diphosphate (ADP). Age, weight, initial platelet count (Pct), plateletcrit (Pct), Hct, and white blood cell count (WBCC) were compared between male and female dogs to assess for statistically significant differences (P <0.05). Aggregation area under the curve (AUC), maximum aggregation (A) and velocity (V) results were analyzed using linear mixed models, controlling for Plt, Pct, Hct and WBCC, and including a random interceptor for subject. Age, weight, initial Plt, Pct, Hct and WBCC did not differ significantly between male and female dogs. AUC, V and A were also not significantly different between gender groups. WBCC was significantly positively associated with AUC, V and A, while Plt, Pct and Hct did not have a significant independent effect. WBCC is positively associated with impedance aggregometry induced by ADP in citrated whole blood samples. Plt, Pct and Hct did not significantly affect results. Large interindividual variation was seen in aggregometry results.