Treatment of anoestrous mares with a synthetic progestagen, allyloestrenol.

The research article investigates the use of a synthetic hormone, allyloestrenol, for treating horses that are not in the breeding cycle. It shows that this method can be effective in inducing the breeding cycle in mares that are not ovulating early in the breeding season.

Research Methodology

• The study was conducted on anoestrous mares, animals that are not in heat or a sexual cycle. Two groups were observed; one group that was initially treated with prostaglandins (43 mares), and a second group composed of mares that didn’t respond to the prostaglandin treatment (29 mares).
• The hormone allyloestrenol was administered for 12 days, at a dose of 0.05 mg/kg body weight. The treatment was given orally.
• After discontinuing the hormone therapy, completed by the gestagen blockade, the researchers monitored the animals for signs of heat. If it was found that a preovulatory follicle could be felt, an additional hormone (2000 IU hCG) was administered to encourage ovulation.
• In some mares, the hormone levels of 17 beta-estradiol (E2) and progesterone (P4) were monitored during the treatment duration and for 10-14 days afterwards.

Results

• A high percentage (86.2%) of the mares treated with allyloestrenol showed favorable signs of the breeding cycle (oestrus) and 65.5% became pregnant.
• The successful oestrus and pregnancy rates reveal that 12-day allyloestrenol treatment appears to be an effective method for inducing the breeding cycle in mares experiencing anoestrus during early periods of the season.
• The researchers suggested that one of the main reasons for mares being in anoestrus is the lack of a functional corpus luteum. This issue can be rectified by administering exogenous gestagen, suggesting a hormonal imbalance.
• Although the treatment method seems to be effective, there’s a need for improvement in timing ovulation, as precise timing is crucial when it comes to breeding management.

Conclusion

• These findings offer a promising solution to induce the sexual cycle in non-breeding horses. However, more research may be required to improve the timing of ovulation.