Mare reproductive loss syndrome (MRLS) has been a primary research project for many veterinarians and scientists since it began causing early and late term abortions, sickness in foals, pericarditis (heart problems), and uveitis (eye problems) in horses in the spring of 2001. Manu Sebastian, DVM, MS, a resident in Veterinary Pathology, and a PhD student at the University of Kentucky’s Gluck Equine Research Center, recently presented a history of MRLS and resulting research, and he also described two studies that had not yet been presented to the veterinary community.

After reviewing clinical signs of MRLS, Sebastian listed the many different hypotheses that have been suggested as the cause of MRLS, including mycotoxins, calici virus (a virus causing lesions in sea lions and pigs), cyanide, poison hemlock, tall fescue, ammonia, and Eastern tent caterpillar (ETC) setae (hairs) and toxic molecules. The ETC have been implicated as the probable cause for the syndromes