The endocrinology of parturition in the mare.

This research article explores the endocrinology or hormonal changes related to late pregnancy and childbirth (parturition) in mares, and how these factors differ from other domestic animals. Notably, it highlights that the hormones that kickstart childbirth in mares are yet unknown, that estrogen and progesterone levels don’t fluctuate significantly during this time, and that there isn’t a clear surge of cortisol (stress hormone) before childbirth. Also, it emphasizes that childbirth in mares is accompanied by a significant increase in prostaglandins and oxytocin which result in uterine contractions and the birth of the foal. It also points out that the safest method to induce childbirth in mares at full term is through administering low-dose oxytocin.

Understanding the Endocrinology of Parturition in Mares

• The article discusses the hormonal changes that occur during late pregnancy and parturition in mares. These changes have been described in detail, but in contrast to other domestic animals, the specific hormones that initiate the process of parturition in mares are still unknown.
• The hormonal factors under discussion primarily include estrogen and progesterone, which normally fluctuate significantly in domestic animals during late pregnancy and parturition. However, in mares, these hormones do not exhibit marked changes, which is a clear distinction from other species.
• Another point of difference is the absence of a clear surge of the stress hormone cortisol just before the mare gives birth. In many other species, a surge in cortisol is often observed as a precursor to labour, but this is not the case with mares.

The Role of Prostaglandin and Oxytocin

• The onset of parturition in mares is associated with a significant increase in the hormones prostaglandin and oxytocin. Elevated levels of these hormones stimulate the contractions of the uterus, leading to the delivery of the foal.
• It is evident from this research that these two hormones play a crucial role in parturition in mares, even though the initiating factors remain unknown.

Inducing Parturition in Mares

• The article concludes by examining different ways to induce parturition in mares that have reached full term. Of all the methods studied, the safest and most popular is the administration of a low dose of oxytocin.
• Oxytocin, apart from its natural role in stimulating uterine contractions, acts as a reliable agent to induce labour in mares, ensuring a controlled and safe birth process.