Vincristine impairs platelet aggregation in dogs with lymphoma

Platelet aggregation before and after administration of 0.5 mg/m(2) of vinc ristine (VCR) was evaluated in 7 dogs with spontaneously occuring lymphoma. Aggregation on platelet-rich plasma separated from blood collected in 3.8% sodium citrate was performed using adenosine diphosphate (ADP), arachidoni c acid (AA), and collagen (COL) as agonists. The slope for aggregation in r esponse to ADP was significantly lower after administration of VCR (P = .03 2). Maximal aggregation after administration of VCR was significantly lower in response to ADP, COL, and AA (P = .03, P = .04, and P = .03, respective ly).