Aerobic and anaerobic bacterial flora in the postpartum mare

Abstract

Equine postpartum uterine bacterial contamination was studied. Thirteen mares were examined at foaling, at foal heat and again at the second estrus if not bred at foal heat (n=7). Twenty-three percent (3/13) of the mares showed no uterine bacterial contamination immediately post partum. This was increased to 77% (10/13) by foal heat and 100% (7/7) by the second post-partum estrus. Few anaerobic bacteria were isolated and were quickly eliminated. Anerobic bacteria do not appear to be a problem in the postpartum mare. The mare is capable of quickly eliminating postpartum uterine bacterial contamination. Endometrial etiology was shown to be a good screening test for uterine bacterial contamination in the postpartum mare. Bacterial endometritis has long been recognized as a major cause of infertility in the mare.5,8,12 Bacterial culture techniques over the years have been improved as have the interpretation of such results. It is generally agreed upon that the isolation of bacteria by itself is insufficient evidence of disease.3,16,17,19,25 Certain bacteria, Streptococcus zooepidemicus, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumonia, are known to be the major bacterial pathogens responsible for most of the cases of endometritis.7,18,26 Isolation of bacteria in pure culture also is considered to be clinically significant; mixed cultures probably indicate insignificant contamination.2,21 The clinician also must consider the quantity of organisms isolated.1,3,7,19,26 Most pathogens occur in large numbers with heavy growth noted when cultured. In addition to kinds and quantity of bacteria isolated from the uterus, there also must be evidence of inflammation detected by physical examination of the genitalia, endometrial cytology and/or endometrial biopsy.4,9,14,15,25,27,28 The presence and significance of anaerobic bacteria in the mare's uterus has not been throughly addressed. It has been documented that aerobic and anaerobic bacteria play a significant role in postpartum uterine infections in the cow.20Fusobacterium necrophorum and Corynebacterium pyogenes apparently have a synergistic effect to increase the severity of postpartum uterine infections in the cow.20,23 Anerobic bacteria, as well as mycoplasmas and viruses, have been suggested as possible causes of endometritis in the mare when evidence of inflammation is present but no aerobic bacteria are isolated.7,14,21,27 The purpose of this study was to document aerobic and anaerobic bacterial contamination of the uterus in the postpartum mare. Endometrial cytology was investigated to determine if there was a relationship between the presence of bacteria in the postpartum uterus and an inflammatory response.