New factors suspects in MRLS

LEXINGTON, Ky. - A new study of last spring's abortion wave known as mare reproductive loss syndrome suggests some new factors that might have predisposed mares to the syndrome.

Researchers funded by the state of Kentucky and the Grayson-Jockey Club Research Foundation announced Wednesday that new factors included the presence of elk or deer at affected farms during the year preceding the outbreak, and an increased amount of white clover in pastures in the four weeks before abortion.

The study also indicated that heavy caterpillar infestation, feeding hay in pastures in a four-week period before the abortions, and a history of abortion in the previous five years also increased mares' risk for MRLS last year, when an estimated 2,500 mares were stricken.

Dr. Noah Cohen of Texas A&M University, one of the researchers who led the study, which compared more than 100 characteristics of mares who experienced MRLS in 2001 with those who bred successfully the previous year, said that "there were unusual conditions influencing the pastures during 2001," including the rise in white clover and caterpillars.

Cohen recommended limiting mares access to the pasture under "similar extraordinary conditions."

The study found that cherry trees and hemlock "were not important risk factors for MRLS-associated early-term abortions and stillbirths."

Although the study did find that white clover and caterpillars were risk factors associated with MRLS, it did not determine whether they were direct causes of the syndrome.