Reducing Breeding-Induced Endometritis by Simplifying Management?

Modern breeding management and assisted reproduction might actually exacerbate the issue of mating-induced endometritis, according to Mats Troedsson, DVM, PhD, Dipl. ACT, a professor of equine theriogenology in the Department of Large Animal Clinical Sciences, at the University of Florida's College of Veterinary Medicine.

"We used to think that bacteria were the only cause of endometritis in the horse," Troedsson said. "We now know that semen can also be a cause." While spermatozoa induce inflammation in the uterus, seminal plasma modulates the inflammation. Troedsson said that semen that has been stripped of most of its natural plasma (as it is when frozen) is more likely to cause persistent inflammation in the uterus than fresh semen. While some inflammation is natural and necessary to clear the uterus of excess semen and bacteria, seminal plasma limits the duration of the inflammatory response. In addition, specific seminal plasma proteins appear to help live spermatozoa safely reach the oviduct even when an inflammation is present in the uterus.

Without plasma, spermatozoa can clump together with inflammatory cells, making it difficult for the sperm to reach the egg in the oviduct. Troedsson suggests that a minimum of 5-10% of plasma be retained to prevent clumping.

Additionally, the method used to administer oxytocin (which causes the uterus to contract and expel fluid) might play a large part in the mare's ability to respond to the therapy.

"The best way to use oxytocin is in small doses, repeated through the day," Troedsson said. The idea comes from the observation of reproduction in a natural setting. Given total freedom, a stallion will tease and breed a mare several times during estrus, triggering a release of the hormone each time.

Troedsson also mentioned that certain alternative treatments, including acupuncture, are gaining popularity in the fight against persistent endometritis. Immunostimulants and corticosteroids are also under investigation, although Troedsson said that both of these options require more research before they will be considered a trusted solution for the condition.

Troedsson and other researchers are continuing to study breeding-induced endometritis, which Troedsson estimates to affect up to 10% of normal broodmares.

About the Author

Erin Ryder

Erin Ryder is a former news editor of The Horse: Your Guide To Equine Health Care.

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