Article Text

Equine Practice
Diagnosis and management of twinning in mares
  1. Anne Schramme-Josson

    Anne Schramme-Josson graduated from the State University of Ghent, Belgium. She worked in equine practice in the UK for 15 years before moving to Cornell University in the USA, where she was a clinical instructor in equine theriogenology. She subsequently completed a residency in theriogenology at North Carolina State University, where she is now a clinical assistant professor in theriogenology.


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.

Statistics from

Request permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.