What’s the most common cause of late-term abortion in horses and remains challenging for veterinarians to diagnose and treat, despite ongoing research? If you said placentitis, you’re right. To bring attendees of the 2013 Society for Theriogenology Conference, held Aug. 7-10 in Louisville, Ky., up to speed on the latest research on the complex topic, C. Scott Bailey, DVM, MS, Dipl. ACT, presented a review of placentitis diagnostics and treatments.

Placentitis—an inflammation of the placenta—is often caused by an ascending infection that enters the mare’s uterus through the cervix. Bailey, an assistant professor of theriogenology at the North Carolina State University (NCSU) College of Veterinary Medicine, explained that placentitis is responsible for 10-40% of late-term abortions in mares; of those cases 60% are of the bacterial variety.

Clinical signs of placentitis often develop late in the course of disease and are generally nonspecific. Bailey said the most common clinical sign he encounters is premature udder development, and less commonly vulvar discharge. However, he noted, many cases simply present with late-term abortion or the birth of a sick or weak foal.

"Despite intense research and clinical focus, diagnosis for most forms of placentitis remains difficult and clinical treatment success remains limited