Oregon State University researchers have reported a link between vesiviruses, which can affect a wide variety of mammals, and mare reproductive loss syndrome (MRLS). University of Kentucky researchers studying MRLS are concerned the results of the study could be misconstrued and say the link of vesiviruses to MRLS is premature.

The Oregon researchers reported a “significant association” between finding antibodies in blood samples for vesivirus and abortion in mares. (Read Oregon’s summary of the experiments here: www.TheHorse.com/ViewArticle.aspx?ID=7141.)

Bruce Webb, PhD, a University of Kentucky entomologist and MRLS researcher, provided many of the samples used in the Oregon study. According to Webb, the OSU report describes a correlation, not a cause.

University of Kentucky MRLS studies have shown little evidence of a virus being the cause of MRLS, such as a fever in affected mares or evidence of direct transmission of the disease between mares. “There is no direct evidence that vesiviruses have caused a single case of MRLS,” Webb said