EFFECT OF ACETYLSALICYLIC-ACID ON PLATELE T-AGGREGATION AND CAPILLARYBLEEDING-TIME IN HEALTHY CATS

The influence of acetylsalicylic acid (ASA) in vitro and in vivo on se veral parameters of the hemostatic system was evaluated in healthy cat s. The aggregation response of cat platelets in vitro was not influenc ed by 10 mu g ASA/ml plasma, whereas ASA concentrations of 35, 70, 100 mu g/ml and of 1 mg/ml consistently inhibited the platelet aggregatio n induced by 0.1 (n = 4 cats) and 0.25 mu g collagen/ml (n = 6 cats). The aggregation response to ADP and thrombin was partially (n = 2) or completely (n = 8) inhibited by an ASA concentration of 5 mg/ml. Admin istration of ASA at a dosage of 10 and 25 mg/kg BW orally and intraven ously yielded a plasma concentration of salicylic acid of 30-42 mu g/m l (10 mg/kg BW) and 50-70 mu g/ml (25 mg/kg BW). All the dosages of AS A produced an inconsistent inhibition of the collagen-induced platelet aggregation (1/5 and 2/5 for the respective groups), whereas the resp onse to ADP and thrombin was not altered. Capillary bleeding time was not significantly altered after the ASA administration. Platelet count and screening tests were not influenced by ASA application. According to the results of this study, ASA as a platelet aggregation inhibitor is not useful for the prophylaxis of thromboembolism in cats.