Effect of oxytocin and flunixin meglumine on uterine response to insemination in mares.

The research studied the effects of oxytocin and flunixin meglumine on the uterine response to artificial insemination in mares, finding that oxytocin rapidly and effectively removed intrauterine fluid and inflammation.

Research Objective

• The aim of the research was to study the influence of oxytocin (known to stimulate contractions) and flunixin meglumine (a drug that inhibits prostaglandins, simulating weak uterine contractions) on the uterine response to artificial insemination (AI) in mares without a history of reproductive failure.

Methodology

• Mares were divided into three groups. One group was administered with saline (control group), one with oxytocin (Group OT), and one with flunixin meglumine (Group FLU).
• The OT group was treated with 0.01 IU/kg of oxytocin 2, 4, 8, and 25 hours after AI. The FLU group was treated with 1.1mg/kg of flunixin meglumine 2 hours post-AI and with saline thereafter.
• Transrectal ultrasonography was used to record the amount of intrauterine fluid (IUF), edema, and the number of uterine contractions before AI and 10 minutes after the treatments. Furthermore, mares were treated with human chorionic gonadotropin 8 hours post-AI.
• After 8-hour or 25-hour scans, a 500-mL uterine lavage and a biopsy were conducted, followed by confirmation of ovulation at 48 hours and pregnancy 14 to 17 days after AI.

Results

• The study showed that, 8 hours after AI, the FLU group had more polymorphonuclear leukocytes (PMNs) in the uterine lavage fluid than the OT group. However, the uterine contraction rates were not significantly different.
• At 25 hours after AI, PMN concentrations were low in all groups and the OT group rarely showed any intrauterine fluid. The biopsy samples from the FLU group showed less inflammation in the stroma but more PMNs in the uterine lumen 8 hours after AI than the control group.
• There was no significant difference in the pregnancy rates across the groups.

Conclusion

• The study concluded that oxytocin effectively and quickly removed intrauterine fluid (IUF) and PMNs after AI, decreasing the duration of postbreeding inflammation.