Periovulatory administration of therapeutic and supratherapeutic doses of firocoxib does not impair induced ovulation or follicular dynamics in mares treated with a GnRH analogue

OBJECTIVE: To evaluate the effects of therapeutic and supratherapeutic periovulatory doses of firocoxib on ovulation and follicular dynamics in mares. MATERIALS AND METHODS: Seventy cycling mares were randomly assigned to receive firocoxib at 0.1 mg/kg (n = 27), firocoxib at 0.3 mg/kg (n = 22), or no treatment (control; n = 21). Treatments were initiated on Day 0, defined as the day of ovulation induction with a GnRH analogue administered intramuscularly, with firocoxib administered intravenously on Day 0 and Day 1 (24 h apart). Follicular diameter and ovulation timing were assessed by transrectal ultrasonography. RESULTS: All mares ovulated within 72 h after ovulation induction, with no ovulatory failures or hemorrhagic anovulatory follicles. Time to ovulation did not differ among groups (P > 0.05). Dominant follicle diameter on Days -2 and -1 and percentage follicular growth between these days were similar across treatments (P > 0.05). CONCLUSIONS: Periovulatory administration of firocoxib, even at supratherapeutic doses, did not appear to impair induced ovulation or follicular development in mares under the conditions of this study.