Efeitos da dipirona, do meloxicam ou da associação de dipirona e meloxicam na hemostasia em cães conscientes

Inhibition of hemostasis by nonsteroidal anti-inflammatory drugs may limit their perioperative use. This study aimed to compare the effects of dipyrone, meloxicam and the dipyrone/meloxicam combination on hemostasis in conscious dogs. In a randomized crossover design, six dogs (18.5 to 30.9 kg) received four intravenous treatments administered one single time allowing at least 15-day washout intervals: dipyrone (25 mg/kg), meloxicam (0.2 mg/kg), dipyrone/meloxicam (25 mg/kg and 0.2 mg/kg, respectively) and control (0.9% NaCl: 0.1 mL/kg). Blood samples were collected through a central venous catheter, before (baseline), 1, 2, 3, 5 and 8 hours after administration of the treatments to perform the whole blood platelet aggregometry (WBPA). The area under the curve (AUC) and the lag time of the impedance changes, caused by platelet aggregation induced by collagen (3.2 mg), were expressed as percent change from baseline. Buccal mucosal bleeding time (BMBT) was measured at baseline and 1, 3 and 5 hours after treatment administration. The percent changes from baseline (medians) were compared by a Kruskal-Wallis and a Dunn’s test (p<0.05). Meloxicam and 0.9% NaCl did not alter WBPA. On the other hand, compared to the control, dipyrone and dipyrone/meloxicam significantly increased the lag time for 2 hours (94 and 97% above baseline after 2 hours, respectively). Dipyrone significantly reduced the AUC compared to the control for 3 hours after administration (47% lower than baseline AUC); while dipyrone/meloxicam significantly reduced the AUC for 5 hours (43% lower than baseline AUC). The BMBT did not differ between treatments. Despite the fact that meloxicam alone did not change WBPA and BMBT, this drug prolonged the inhibition of platelet aggregation induced by dipyrone. However, this effect does not increase the risk of bleeding in healthy and conscious dogs.