EFFECTS OF ASPIRIN DOSE ESCALATION ON CANINE PLATELET FUNCTION AND URINARY THROMBOXANE AND PROSTACYCLIN LEVELS

摘要

Aspirin is commonly used in an effort to prevent thrombus formation in dogs. High-dose aspirin (10 mg/kg, PO, q 12h) reliably inhibits platelet function and thromboxane A2 (TXA2) synthesis, but can be associated with unacceptable side effects, including inhibition of prostacyclin synthesis, which counteracts the effects of inhibition of TXA2. Lower doses of aspirin, in contrast, inhibit platelet function and TXA2 synthesis, have few side effects, and allow ongoing prostacyclin synthesis. However, low-dose aspirin therapy at standard dosage (0.5-1 mg/kg, PO, q 24h), does not reliably inhibit platelet function, a phenomenon known as "aspirin resistance". Aspirin-associated platelet dysfunction has been shown to be highly dose-dependent, suggesting that traditional "low-doses" of aspirin may be under-dosing canine patients. Our study used incremental increases in dosages to determine the dose of aspirin that consistently inhibited platelet function and TXA2 synthesis without inhibiting prostacyclin synthesis.