Equine endometritis: a review of challenges and new approaches

Abstract

Endometritis in the mare begins as a normal physiological inflammatory response to breeding that involves both a mechanical and immunological response pathway activated to rid the uterus of semen and bacteria. With successful resolution of this inflammation, the mare’s uterus will provide a hospitable environment for the development of the semi-allogenic conceptus. If the mare fails to resolve this inflammatory response within 48 hours of breeding, she will become susceptible to persistent breeding induced endometritis (PBIE) which will have detrimental effects on her fertility. This condition can then predispose the mare to bacterial or fungal endometritis leading to further degeneration of the endometrium. Optimisation of the mare’s fertility requires a fine balance between allowing the natural immune response of the endometrium to its exposure to allogenic semen to run its course, and yet preventing its progression to PBIE or the involvement of infectious agents. This review discusses the challenges presented by PBIE, latent infections, biofilms, fungal infections and the need to utilise diagnostic methods available and implement targeted treatments to optimise fertility in the mare.

Alterations in the Expression Profile of Serum miR-155, miR-223, miR-17, miR-200a, miR-205, as well as Levels of Interleukin 6, and Prostaglandins during Endometritis in Arabian Mares

“…No doubt that proper uterine function is regulated by different mediators such as miRNA [45], which is responsible for activation or inhibition certain target genes, depending on cell signaling. Uterine infection does not only affect female fertility by perturbing uterine function, but also could prolong ovarian cycle [46]. Therefore, to tackle the continuing fertility problems associated with uterine inflammation, understanding the molecular regulatory mechanisms associated with the inflammatory immune response is crucial to design appropriate therapeutic drugs [47].…”

Antimicrobial Resistance in Equine Reproduction

“…The presence of lymphocytes and plasma cells for prolonged periods leads to chronic degeneration in the endometrium. It is not known whether bacteria are the primary initiators of these events or are secondary invaders of the affected tissue [ 35 ].…”

“…In contrast, neomycin administered by the intrauterine route was transferred to the blood stream, although the uptake depended on the stage of the oestrous cycle and whether or not infection was present [ 41 ]. It should be noted that most of the studies that have been performed on transfer of antibiotics to the uterus after systemic administration or between the uterus and the rest of the body after intrauterine administration have been carried out in healthy animals [ 35 ]; the pharmacodynamics may be different in the presence of pathology. Studies in cattle report contradictory findings regarding penetration of antibiotics into the uterus following systemic administration.…”

A Novel Approach to Minimising Acute Equine Endometritis That May Help to Prevent the Development of the Chronic State

“…The cause of persistent endometritis is multifactorial, ranging from physical factors, such as age and conformation of the perineal area, to an exaggerated post-breeding response of the uterine epithelium ( 2 ). Chronic endometritis may arise from repeated episodes of acute endometritis ( 3 ). Alternatively, it may be bacterial in origin ( Figure 1 ), together with underlying physical problems relating to the effectiveness of the cervix as a barrier to the entry of microorganisms ( 4 ).…”