Streptococcus ovis associated abortion in an Icelandic mare

Streptococci are well-known opportunistic bacterial abortifacients in mares. Colonization of the pregnant uterus is considered to happen after transcervical migration of bacteria from the lower genital tract mucosa. Streptococcus ovis is a pathogen mainly associated with inflammatory lesions in sheep. This species has not been reported in association with disease in horses. In the present case, S. ovis was isolated in monoculture from the lung of an 8-months-old equine fetus and was associated with development of acute suppurative bronchopneumonia, umbilical cord cellulitis and placentitis in the cervical star region of the allantochorion. The mare had been in a pasture together with sheep. One week prior to abortion, a double-guarded uterine swab had been inserted into the cervical canal by a veterinarian, who was unaware of the mare being pregnant. This probably damaged the cervical mucus plug thus allowing S. ovis bacteria to pass the cervical canal and colonize the placenta.