Isolation of subspecies from an abdominal abscess in an adult mare.

A 12-year-old Warmblood mare was referred for evaluation of behavioral changes not explained by general physical examination or lameness evaluation. Transrectal ultrasound examination was performed to determine if the behavioral changes were related to ovarian abnormalities, and a large abscess was found near the base of the cecum. Laparoscopic-guided aspiration and lavage of the abscess cavity followed by injection of benzyl penicillin G was carried out. Culture of the lavage sample yielded subspecies , an organism not previously reported as an etiological agent in abdominal abscesses in horses. The mare was treated after surgery with an extended course of antibiotics (minocycline q12h for 10 days followed by enrofloxacin q24h for 42 days). The mare resumed work in competitive eventing 10 months after surgery, and the behavioral complaints had resolved according to the owner. Key clinical message: We describe the diagnosis and treatment of a mare with an abdominal abscess from which subspecies was cultured. This organism has not previously been reported as an etiological agent in abdominal abscesses in horses.