Uterine Cultures from Mares in Central Florida

This study included 8,296 uterine cultures from 7,665 mares of different breeds in central Florida.  The percent of positive uterine cultures varied by year and ranged from 27-43%. Overall, potentially pathogenic bacteria were isolated from 31% of cultures.

The three most frequently isolated bacteria were commonly expected uterine pathogens and included Escherichia coli, Streptococcus zooepidemicus, and Enterobacteriaceae species. These bacteria are often found on the horse’s skin or in its intestinal tract. Streptococcus zooepidemicus was most likely to produce uterine inflammation that could be observed with uterine cytology (looking for white blood cells using a microscope).

The study also investigated patterns of antibiotic susceptibility and resistance in uterine bacteria over time. Fortunately, most of the antibiotics commonly chosen to treat uterine infections were effective against the bacteria that were isolated. However, there was some antibiotic resistance to antibiotics routinely used in equine practice.

It is important to use antibiotics only when needed and infection is present to prevent antibiotic resistance. Treating uterine infections based upon culture and antibiotic sensitivity allows veterinarians to choose the antibiotic that is most likely to kill the pathogenic bacteria and resolve the infection.

Davis, H.A., M.B. Stanton, K. Thungrat, and D.M. Boothe. 2013. Uterine bacterial isolates from mares and their resistance to antimicrobials: 8,296 cases (2003-2008). Journal of the American Veterinary Medical Association242:977-983.