Serological and Uterine Biomarkers for Detecting Endometritis in Mares

SIMPLE SUMMARY: In the mare, infectious/inflammatory pre-breeding endometritis may be exacerbated by post-breeding endometritis (PBE), which occurs due to the reactivity of the uterus to insemination. PBE can be treated post-insemination; however, it is difficult to monitor the outcome of the treatment due to negative interference in embryonic development following the collection of uterine samplings. Indirect findings capable of providing information on the evolution of this pathology and verifying the response to treatments, therefore, would be highly recommended. This study examined ten parameters in blood and uterine fluid associated with the (anti)oxidant status, inflammation, and protease regulator potential and possible markers of endometritis in the mare. Endometritis has been evaluated with both culture and cytological techniques; the latter has been carried out by both classical and fluorescence techniques. Among the parameters examined in the blood serum, only one of them, the ferric reducing ability of plasma (FRAP) assay, a marker of the antioxidant power, allowed significant discrimination between the mares diagnosed as cytologically positive and negative for endometritis. This result provides an important piece of information in the development of indirect methodologies for the diagnosis of endometritis in the mare. ABSTRACT: Serological analysis may provide relevant information on endometritis diagnostics. Therefore, mares scheduled for AI with refrigerated semen, at the time of heat signs, underwent blood and uterine fluid samplings using a swab, uterine lavage for culture analysis, and treatment with human chorionic gonadotropin to induce ovulation. After 24–28 h, the mares were inseminated and, if positive at the culture test, treated with antibiotics chosen based on the susceptibility test. Uterine cells obtained by swabs were used for cytological examination with both classical and fluorescence techniques. Blood serum and uterine fluid samples were analyzed for assessing parameters related to redox balance, inflammation, and protease regulator potential. In blood serum, total antioxidant capacity, measured as the ferric reducing ability of plasma (FRAP), was significantly lower in cytologically endometritis-positive than -negative mares. In the uterine fluid, total thiol levels (TTL), nitric oxide metabolites (NO(x)), protease activity and total protein content varied significantly between groups. Although the cytological examination was more capable of discriminating between endometritis-positive and -negative mares in relation to the parameters examined, no statistically significant differences emerged in terms of pregnancy rate in relation to cytological and culture diagnosis as well as in mares diagnosed as positive and negative for endometritis.