Factors affecting the uterine inflammatory response to semen

Abstract

At the time of breeding or insemination the uterus is exposed to seminal components, bacteria and debris. This results in an inflammatory response characterized by the influx of polymorphonuclear neutrophils (PMN) into the uterine lumen. (1) The purpose of the inflammation is to clear from the uterus defective and excess sperm, and other contaminating agents. The influx of PMNs into the uterine lumen results in phagocytosis of sperm, bacteria and release of prostaglandin, which causes uterine contractions. (2) This inflammation is quickly cleared from the uterus within 36 hours. In fact, in most mares that are resistant to delayed post breeding endometritis, the uterus is clear of fluid by 24 hours with the peak of PMNs and uterine fluid occurring at 12 hours after insemination. It has often been stated that insemination of mares with frozen semen results in a greater inflammatory response However there are limited data on the response of the mare`s uterus to various types of semen. This manuscript addresses some of the factors that affect the severity of the inflammatory response after breeding.