Efeitos da utilização de fenilbutazona e meloxicam sobre o desenvolvimento de folículos pré-ovulatórios em éguas

Abstract

Nonsteroidal antiinflammatory (NSAIDs) drugs, as meloxicam and phenylbutazone, are used for the treatment of many disorders in mares and could interfere in reproductive activity by inhibiting COX-2 and, consequently, inhibition of PGs formation. The aim of this study was to evaluate the effects of administration of NSAIDs in developing pre-ovulatory follicles in mares. Eleven mares were used in the study during three consecutive cycles and ultrassonographic examination was performed each 12 hours. When follicles of 32 mm diameter were detected, deslorelin (1 mg) was administrated to induce ovulation. The first cycle was used as control and they received the same dose of deslorelin, without NSAIDs administration. In subsequent cycles the mares were treated with deslorelin and NSAIDs, as well: in the second cycle, each horse received the same dose of deslorelin associated with 4.4 mg/kg of phenylbutazone. In the third cycle associated deslorelin was administered at 0.6 mg/kg of meloxicam, both used once a day, until the moment of ovulation or beginning of follicular haemorrhage. In the control group all mares ovulated between 36 and 48 hours after induction. During the cycle of treatment with meloxicam, ten mares (92%) failed to ovulate and during the cycle of treatment with phenylbutazone, nine (83%) failed to ovulate, and intrafollicular hyperechoic spots were observed in ultrasound images, consistent with hemorrhagic follicles, evolving to anovulatory follicles luteinized. It can be inferred that treatment with meloxicam and phenylbutazone, in therapeutic doses, induced the formation of intrafollicular haemorrhage and luteinization of anovulatory follicles.