Intrafollicular treatment with prostaglandins PGE2 and PGF2α inhibits the formation of luteinised unruptured follicles and restores normal ovulation in mares treated with flunixin-meglumine.

The research article investigates the effect of intrafollicular treatment with prostaglandins PGE2 and PGF2α on mares treated with a drug called flunixin-meglumine. It concludes that this treatment can restore normal ovulation and even result in successful pregnancy, providing a potential solution to instances of ovulatory failure in mares.

Objective and Background

• The primary aim of the study was to understand the impact of administering prostaglandins PGE2 and PGF2α directly into the ovarian follicle during the periovulatory period on ovulation and pregnancy in mares who have been treated with flunixin-meglumine.
• The researchers state that the most common pathological anovulatory (the inability to release an ovule) condition in mares is “Haemorrhagic anovulatory follicle,” where the cause is still unknown.
• Treatments with flunixin-meglumine have the ability to prompt the formation of luteinised unruptured follicles, which mimic the characteristics seen in haemorrhagic anovulatory follicles.

Methodology

• In a crossover study, five mares underwent observation over two oestrous (female reproductive) cycles each. Every 12 hours from Hour 0 (the start being marked by the treatment of human chorionic gonadotrophin), each mare was administered with 1.7 mg/kg bwt of flunixin-meglumine intravenously.
• During the treatment cycles, at Hour 32, the preovulatory follicle (a follicle ready to release an egg) was punctured. The researchers then introduced 0.5 ml of a solution containing 500 µg of PGE2 and 125 µg of PGF2α into it. In the control cycles, injection water was administered into the follicle at the same time.
• In three of the total cycles (both control and treatment), mares were also inseminated at Hour 24.
• An ultrasound examination was carried out between 36 and 72 hours to diagnose ovulation or the formation of luteinised unruptured follicles, and 14 days after to confirm pregnancy.

Results

• All mares treated intrafollicularly with prostaglandins PGE2 and PGF2α ovulated normally, with a 100% ovulation rate 36-48 hours after human chorionic gonadotrophin treatment.
• In contrast, 4 out of 5 control cycles (80%) resulted in the mares developing an LUF, a statistically significant outcome (P<0.05).
• All of the three mares inseminated in the treatment cycles became pregnant. In contrast, none did in the control cycles.

Conclusion

• The paper concludes that treatment with PGE2 and PGF2α successfully overcomes the anovulatory effect of flunixin-meglumine, highlighting its potential as a therapeutic option in cases of ovulatory failure in mares.