Diagnosis and management off twinning in mares

Abstract

TWIN and triplet births are common in sheep and goats, but multiple births occur less frequently in uniparous species such as cattle and horses. Twinning is an important non-infectious cause of pregnancy loss in mares and should not occur on well-managed breeding farms. The equine uterus is not well designed to carry twins, as the entire endometrial surface is required for the placental development of a single fetus. The membrane shared between two vesicles does not function as a nutrient supply and therefore cannot fulfill the nutritional requirements of both fetuses, which eventually causes abortion of one or both of them during mid- to late gestation. This can result in considerable economic loss to the equine breeding industry. Recently, the use of transrectal ultrasonography has significantly improved the ability of veterinarians to diagnose and manage twin pregnancies more accurately compared with digital examination of the uterus per rectum. This article describes how to diagnose twinning at an early stage and how it can be managed appropriately to ensure the birth of a single viable foal.