Three concerned equine practitioners visited the Gluck Equine Research Center the first part of May 2001 to discuss what they had discerned as unusual activity in their broodmare practices. The rest of May and early June encompassed our initial exhausting experiences with mare reproductive loss syndrome (MRLS). Through it all, we learned a great deal not only about the horses we care for, but also about ourselves. Mostly, we learned that we need one another–owners, managers, practitioners, researchers, and consultants–because only a strong cooperative effort would allow us to meet the challenge of MRLS.

May and June could be characterized as surveillance and damage control on a 24-hour basis. Following the initial release of MRLS descriptions, we spent long hours examining and rechecking early-bred mares for signs of change on ultrasound examination as managers worked tirelessly. This was all too often an exercise in frustration; we watched helplessly as mares aborted in clear sight on an ultrasound screen. This frustration was only multiplied by long nights of complicated foalings. As practitioners, we stood alongside managers and dedicated foaling staffs disgusted that all too often our best efforts only produced a compromised neonate and a distressed mare.

There were two other clinical entities associated with MRLS. Some young horses and adults showed signs of lethargy and depression that resulted from copious amounts of fibrinous fluid around their hearts (pericarditis). Simultaneously, veterinarians saw young horses with an unusual eye condition occurring in only one eye, with diffuse yellow discoloration consistent with a profound and non-responsive uveitis.

As we dealt with MRLS, countless people who support our industry toiled at the Livestock Disease Diagnostic Center and the Gluck Center. Dedicated pathologists and their assistants processed unimaginable numbers of specimens to rule out known causes for these events and to help shed light on the pathologic findings. Specialists from the Gluck Center processed farm surveys to gain epidemiological information. UK’s Agronomy Department looked at pastures, forage samples, and soil analyses to characterize the environmental settings of these unusual events