Endometritis in old mares

A transient uterine inflammation is considered physiological after breeding, and normally subsides within 48 hours in reproductively healthy mares. However, a subset of mares fails to clear the inflammation in a timely fashion and subsequently develop persistent endometritis. The causes and mechanisms of persistent endometritis are multifactorial. In addition to compromised myometrial activity, a defective uterine innate immune response has been attributed to the disease. While persistent endometritis can affect all mares, older mares are particularly at risk, as advanced age has been associated with susceptibility to persistent endometritis. Horses of advanced age undergo an alteration of the immune system including a low-grade, systemic pro-inflammatory response, however a direct correlation with this systemic alteration and susceptibility to persistent endometritis has not yet been investigated. There are multiple treatment strategies available for resolving persistent endometritis, including ecbolics, lavage, antibiotics, immunomodulators, acupuncture, and corrective surgery. While it will never be possible to prevent a mare from ageing, treatments adapted towards the unique needs of the aged mare can improve fertility. Future directions of research into persistent endometritis in the old mare should continue to focus on how ageing affects the reproductive and immune systems.