Objective—To determine effects of therapeutic dosages of aspirin, carprofen, deracoxib, and meloxicam on platelet function and systemic prostaglandin concentrations in healthy dogs.
Animals—10 hound-crossbred dogs.
Procedures—Aspirin (10 mg/kg, PO, q 12 h), carprofen (4.4 mg/kg, PO, q 24 h), deracoxib (2 mg/kg, PO, q 24 h), meloxicam (0.1 mg/kg, PO, q 24 h), and a placebo were administered for 7 days in a random order to each of 10 healthy dogs; there was a 21-day washout period between subsequent treatments. One-stage prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen concentration, and plasma concentrations of thromboxane (TX)B2 and 6-keto prostaglandin (PG)F1α were measured before and after treatment administration. Platelet function was assessed by use of a platelet-function analyzer and aggregation.
Results—Aspirin, carprofen, and meloxicam did not significantly affect platelet function. Deracoxib caused a mild decrease in platelet aggregation induced by 50μM ADP. Platelet number, Hct, PT, aPTT, and plasma TXB2 and 6-keto PGF1α concentrations were unchanged after NSAID administration. Meloxicam administration resulted in a significant decrease in fibrinogen concentration, but results remained within the laboratory reference interval.
Conclusions and Clinical Relevance—Oral administration of commonly used NSAIDs at therapeutic dosages in healthy dogs did not alter plasma TXB2 and 6-keto PGF1α concentrations. Deracoxib administration resulted in a minor abnormality in platelet aggregation. Anti-inflammatory doses of aspirin did not affect platelet function as measured by use of optical aggregometry and a platelet-function analyzer. Further evaluation of the effects of aspirin and cyclooxygenase-2–selective inhibitors on hemostasis should be performed.