Surgical removal of one conceptus from fifteen mares with twin concepti.

The research article discusses a surgical technique to remove one embryo from mares with twin embryos. Trials indicated a higher survival rate for one twin than for both in bicornuate mares, but survival rates in unicornuate mares remained low; the mares, however, could be rebred successfully.

Understanding the Method and Purpose of the Research

• The researchers aimed to test and analyse a surgical technique that’s used to remove one embryo from pregnant mares carrying twin embryos. This usually happens beyond 35 days of gestation.
• The intention behind this is to increase the survival chances of the remaining embryo. Twin pregnancies in horses often lead to complications, and the mortality rate is higher. Removing one embryo can potentially mitigate this issue.

Research Findings and Observations

• A total of 15 mares with twin embryos, between 41 to 65 days of gestation, underwent the surgical procedure.
• Eight of these mares had bicornuate (two uterine horns) twin embryos, and seven had unicornuate (single uterine horn) twin embryos.
• The procedure also involved administering of progesterone to maintain the pregnancy if surgical trauma causes prostaglandin release and indeed luteolysis (the regression of the corpus luteum, which produces progesterone necessary for maintaining pregnancy).
• Flunixin meglumine, a non-steroidal anti-inflammatory drug, was also given around the time of operation to minimize the release of prostaglandins (lipid compounds with diverse hormone-like effects). Both these steps were taken as precautionary measures to ensure that the remaining fetus could develop normally.

Results and Impacts of the Surgical Procedure

• Out of the eight mares with bicornuate twin embryos, five delivered a single viable foal. In one mare, the remaining fetus was alive 4 days after the surgery, but the mare had to be euthanized due to a fractured femur.
• All the fetuses in the seven mares with unicornuate twin embryos did not survive. This lower survival rate was mainly attributed to disruptions of the remaining chorioallantois (part of the placenta in mammals) during the surgical process.
• Despite this, a positive outcome was that thirteen of the mares were successfully rebred. This suggests that while the procedure may have limited success in terms of survival rates, it doesn’t necessarily affect a mare’s ability to conceive again.