Clinical and endocrine studies during normal and induced parturition in mares.

This research paper studied normal and artificially induced labor in horses, specifically examining hormone delivery and the subsequent effects on foal conception and term. It revealed that different methods of induction showed variations in timing and pregnancy outcomes.

Methodology

• This study involved three groups of mares. Six mares between day 327 and 346 of pregnancy were induced with oxytocin (Group I), six mares between day 315 and 330 of pregnancy were induced with a combination of fluprostenol and oxytocin (Group II). The control group consisted of 4 mares allowed to reach full term (322-340 days) and deliver naturally.

Results

• In Group I, parturition took place within 24-102 minutes with a standard deviation of 31.6 while in Group II, it took place within 160-185 minutes with a standard deviation of 10.86.
• The expulsion of the afterbirth varied greatly in the two groups, taking between 7 and 206 minutes in Group I, and between 7 and 73 minutes in Group II.

Post-Parturition Effects

• Three mares in Group I demonstrated foal heat, with all three conceiving and two successfully reaching term. The remaining three mares experienced heat around a month after delivery, with two conceiving but one suffering an abortion and the other resorbing. The third mare remained in anoestrus for 3-4 months.
• In Group II, three mares showed foal heat with two being served. Both of these conceived, and one carried a foal to term. The remaining mares showed oestrus one to two months after parturition. They were served, resulting in one conception which subsequently resorbed.

Conclusion

• In conclusion, the paper provides evidence that inducing parturition in mares using hormones can vary effect on post-partum fertility in mares, with implications for the veterinary and horse-breeding fields.