Postcoital uterine microbe colonization and endometritis in the mare

In the mare, natural breeding is associated with bacterial contamination of the reproductive tract. The purpose of this study was to examine postcoital bacterial contamination and the resulting inflammatory response of the uterus. Uterine swabs for bacteriological and cytological examination were obtained from 80 mares. Each mare was sampled once between 4 and 69 hours postbreeding. In mares which did not conceive, sampling was repeated at the following estrus. The findings were compared with those obtained prior to breeding and correlated with the breeding outcome. Bacteria were cultured from 72.5% of the postcoital swabs. There was a wide spectrum of organisms which included species known as potential causes of endometritis. Neutrophilic granulocytes were found in varying concentrations in 48.8% of cases. In 16.3% of mares both bacteriological and cytological examinations were negative. Mares with positive bacteriological and/or cytological results at the postcoital examination had better foaling rates compared to the remaining mares (p less than 0.05). The postcoital findings did not correlate with those of the prebreeding examination, or with the interval between breeding and sampling, or with the different stallions.