Persistent bacterial communities covering a mare’s uterine surface—called biofilms (seen here in a test tube)—cause inflammation, make it difficult for mares to get pregnant, and are costly and time-consuming to treat. | Photo: Courtesy Dr. Ryan Ferris

Persistent bacterial communities covering a mare’s uterine surface spell trouble. These so-called “biofilms” cause inflammation, make it difficult for mares to get pregnant, and are highly tolerant of antimicrobial treatment, making them costly and time-consuming to treat. But one veterinarian has confirmed that a combination of drugs can disrupt these films in mares, potentially making the uterus a happier place for embryo attachment and pregnancy.

Ryan Ferris, DVM, Dipl. ACT, of Summit Equine, in Newberg, Oregon, has studied biofilms extensively, particularly in mares with endometritis (inflammation of the endometrium, or uterine lining). He presented his most recent findings at the 2018 American Association of Equine Practitioners Convention, held Dec. 1-5 in San Francisco, California.

In previous in vitro (in the lab) studies, he’d found that a combination of the antibiotic ceftiofur and the buffering chelating agent tris-EDTA effectively killed bacteria living a biofilm lifestyle. Based on scanning electron microscopy the tris-EDTA broke up the biofilm material protecting the bacteria, allowing the antibiotic to better penetrate the plaques and kill them. So, he sought to confirm this finding in mares