Vincristine impairs platelet aggregation in dogs with lymphoma

Platelet aggregation before and after administration of 0.5 mg/m(2) of vincristine (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), arachidonic acid (AA), and collagen (COL) as agonists. The slope for aggregation in response to ADP was significantly lower after administration of VCR (P = .032). Maximal aggregation after administration of VCR was significantly lower in response to ADP, COL, and AA (P = .03, P = .04, and P = .03, respectively).