Gauging MRLS Impact a Tough Task

It appears the number of incidents and symptoms of mare reproductive loss syndrome in Central Kentucky are slowing, but there is still no definitive way to arrive at that conclusion. The number of fetuses taken to the University of Kentucky's diagnostic lab so far this year do not approach the number identified with MRLS-related symptoms in 2001, and area veterinary clinics are reporting less MRLS traffic.

A recent unofficial survey by Dr. Stuart Brown of the reproductive veterinarians at Hagyard-Davidson-McGee veterinary clinic near Lexington shows a preliminary 12% early fetal loss rate among 2,103 mares in that practice.

Brown asked his peers to look at the mares they checked between May 6-17 that were 45 or more days into their pregnancies. Of the 2,103 mares, 255 exhibited early loss or early-term abortions. Though the numbers are not definitive, they are one of the first clear indications of the number of losses in 2002.

As for a total statistical study, the suggestion met with a positive response at the May 7 meeting of the Kentucky Thoroughbred Farm Managers' Club. However, club president Eric Hamelback said putting that into practice has been a challenge.

Ideally, his group would already have completed surveys in hand, so farm managers and owners could get a standard by which to compare their rate loss. Officials at the University of Kentucky, however, want to wait until June 1 in hopes of ending up with a more definitive tally of MRLS effects in 2002.

"Our time frame is different than their time frame," said Hamelback, one of the managers of Frank Stronach's Adena Springs Farm. "It's very frustrating. We feel like in some aspects our hands are tied."

The KTFMC could disseminate the survey, but the organization doesn't have the manpower or capability to tally the statistics as effectively as researchers.

Through May 11, 112 MRLS-related fetuses were tested at the diagnostic center. About 529 fetuses, both late- and early-term abortions, were recorded in 2001. On May 16, the Kentucky Department of Agriculture issued a statement that said no new cases of horses displaying symptoms of MRLS had been admitted to veterinary clinics in the area for at least 72 hours. However, most of the losses due to MRLS this year seem to be in the form of early fetal loss, which does not require hospitalization.

Veterinarians are still finding mares that were pregnant after 30 days but have lost their foals somewhere between 45 and 70 days. Sometimes the fetuses are recovered, sometimes they are not, but the mares themselves do not show signs of poor health. However, because of the late date at which fetal death occurs, the mares' bodies react as though they are still pregnant, and therefore are unlikely to come back into heat before the end of the 2002 breeding season.