[Spontaneous and manual embryo reduction in mares: a twin prevention programme].

The research article focuses on how to best manage twin pregnancies in mares, either through allowing natural reduction or manual embryo reduction based on factors like the time of diagnosis and type of embryo fixation.

About the Research

The study analyzed literature data as well as data from 67 twin pregnancies of mares to identify factors crucial to the decision of how to manage twin pregnancies at different stages of gestation. Two primary methods were discussed:

• Spontaneous reduction: This is the natural process through which the body reduces the number of viable fetuses in a pregnancy, most commonly in the early stages.
• Manual embryo reduction: This is an artificial procedure where one of the embryos is physically removed by a veterinarian.

Key Determinants

The researchers identified several determinants that guide the choice of managing twin pregnancies in mares:

• Timing: Manual embryo reduction is recommended when a twin is diagnosed before the 16th day post ovulation.
• Type of fixation: The way the embryos are positioned is a crucial determinant. Manual embryo reduction is preferred when the embryos are bilateral (situated in both uterine horns) or unilateral non-adjacent (situated separately in one uterine horn), and the procedure should be done as early as possible.

Comparison of Natural vs. Manual Reduction

According to the research, up till the 30th day of gestation, the chance of natural reduction for unilateral adjacent twins (twins situated close together in one uterine horn) is higher than the success rate of manual reduction. However, after day 30, manual embryo reduction is a better choice.

Summary of findings

The study presents a twin prevention program based on its findings, which outlines how to avoid twin pregnancies in mares after the development of endometrial cups. This is significant as twin pregnancies can often pose health risks to the mare and the foals.

By considering the timeframe of the pregnancy and the type of fixation of embryos, either spontaneous or manual reduction can be selected as a beneficial method to manage twin pregnancies in horses. It provides a guide for veterinary practitioners to increase the potential of successful pregnancies in mares carrying twins.