Uterine inflammatory conditions in cows: Types and etiopathogenesis

Abstract

Uterine inflammatory conditions with associated fertility disorders are still a serious problem in dairy cow breeding, causing significant economic losses for breeders. Losses result from the costs of uterine infection treatment, fertility disorders, low pregnancy rates, reduced production of milk and the culling of the best cows in the herd due to infertility. According to literature data, uterine inflammatory conditions in cows are closely connected with the postpartum period, and reproductive system infections that occur at this time may persist beyond the postpartum period and cause reduced fertility in cows. Pathogenic microbiota are an underlying cause of the development and persistence of uterine inflammatory conditions. The microorganisms with an affinity for the endometrium that are most frequently isolated from the uterus of cows with metritis and endometritis are Trueperella pyogenes, Escherichia coli, Fusobacterium necrophorum and Prevotella melaninogenicus. No infectious agents may be detected in some inflammatory conditions that are related to the disregulation of intracellular prostaglandin synthesis in uterine endometrial cells. This condition, which is due to infection, may persist for differing periods of time after the elimination of pathogens and may impair the fertility of cows. It is currently believed that the persistence of inflammatory conditions of the uterus depends on the level of anti-infective immunological mechanisms, which not only eliminate pathogens and damaged tissue, but also protect the endometrium thanks to their regulatory properties. Not all defence mechanisms in the uterus have been discovered. Phagocytosis is the first and most important mechanism of defence against pathogens in the uterus of cows, involving specialized phagocytic cells, mainly neutrophils, monocytes and macrophages, which belong to the innate immune mechanisms, as well as migrate from blood at the inflammation site as a specific response. Immune system cells and endometrial epithelial cells, which until recently have been believed to be only a passive barrier to microorganisms, are actively involved in the recognition and initiation of the antiinfective immune response. According to many authors, disorders of the local mechanisms of uterine immunity are a basic cause of metritis and endometritis in dairy cows.