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

Research Overview

• This study investigated whether giving mares therapeutic or higher-than-therapeutic doses of the drug firocoxib around the time of ovulation affects their ability to ovulate or the development of follicles when ovulation is induced by a GnRH analogue.
• The findings showed that firocoxib did not interfere with ovulation or follicle growth under the tested conditions.

Background and Purpose

• Firocoxib is a nonsteroidal anti-inflammatory drug (NSAID) commonly used in veterinary medicine to manage pain and inflammation.
• Ovulation induction using GnRH analogues is a common reproductive management tool in mares to control or synchronize timing of ovulation.
• Since prostaglandins and inflammation are involved in follicle rupture and ovulation, NSAIDs like firocoxib could potentially impair this process.
• The study aimed to test whether periovulatory administration (around the time of ovulation) of firocoxib at therapeutic or supratherapeutic doses would affect ovulation success or follicular dynamics in mares.

Methods

• Seventy cycling mares were randomly divided into three groups:
• 27 mares received firocoxib at 0.1 mg/kg (therapeutic dose)
• 22 mares received firocoxib at 0.3 mg/kg (supratherapeutic dose, 3x the therapeutic dose)
• 21 mares received no treatment and served as controls
• Day 0 was defined as the day of ovulation induction using a GnRH analogue administered intramuscularly.
• Firocoxib was given intravenously twice: once on Day 0 and again 24 hours later on Day 1.
• Follicle size measurements and timing of ovulation were assessed daily using transrectal ultrasonography.

Results

• All mares, across all groups, ovulated successfully within 72 hours of ovulation induction.
• No mares showed ovulatory failure or formation of hemorrhagic anovulatory follicles, indicating normal ovulatory responses.
• Time elapsed to ovulation after induction was not significantly different among the three groups (no difference between treated and control mares).
• Dominant follicle diameters measured two days and one day before ovulation induction were similar across all groups.
• The percentage growth of follicles between these two pre-ovulation days was also similar, suggesting firocoxib did not affect follicular growth dynamics.

Conclusions and Implications

• The periovulatory administration of firocoxib, even at doses three times higher than therapeutic levels, did not impair ovulation induction in mares treated with GnRH analogue.
• Follicular development proceeded normally, with no negative impact on dominant follicle growth.
• These findings suggest that firocoxib can be safely administered around ovulation in mares without compromising reproductive function related to induced ovulation.
• This supports the use of firocoxib for pain or inflammation management in breeding mares without fear of impairing ovulation timing or success under similar clinical conditions.