During the reproductive career of the mare, the uterus is repeatedly challenged by microorganisms, particularly in relation to breeding and foaling. In situations with suboptimal closure of the vulvar, vestibular, and/or cervical seal, the microbial exposure is intensified. The presence of dormant Streptococcus species in the uterine lining indicates that such mares are latently infected. Induction of the bacterial metabolism and growth allows detection of the bacteria at the uterine luminal surface using regular diagnostic techniques in mares that previously have been found to be culture negative. The metabolically active bacteria also regain susceptibility to regular antibiotic treatment, thus allowing for the efficient clearance of the infection. Systemic antibiotics are recommended in latent infected mares following activation and diagnosis. Systemic antibiotics allow clearance of active bacteria located deep within the endometrium.