An equine abortigenic disease known as Mare Reproductive Loss Syndrome (MRLS) significantly impacted the Ohio Valley in the springs of 2001 and 2002 but was not associated with a large number of losses in 2003. MRLS was not associated with other agents known to cause equine abortions. It is a new or emerging disease that caused over $300 million in economic losses in the year 2001 alone. Epidemiological evidence associated incidence of the disease with exposure to eastern tent caterpillars (ETC) and their preferred host, black cherry trees. To determine if exposure to ETC caused MRLS, experiments were conducted in 2002 that manipulated exposure of pregnant mares to ETC and their excrement. The initial studies were performed in the field under experimental conditions designed to simulate environmental exposure. In the first experiment, equine abortions were induced by exposure to ETC with symptoms that were consistent with MRLS in 14 of 19 mares receiving ETC treatments. A subsequent study established that abortions were induced by feeding ETC larvae (50g/mare/day), that autoclaving inactivated the abortigenic agent, and that frozen control larvae (gypsy moth) did not induce MRLS-type abortions. We are currently fractionating the insect to characterize and identify the abortigenic agent. Taken togethor our studies support the hypothesis that ingestion of ETC larvae induced the MRLS equine abortions.
Species 1: Lepidoptera Lasiocampidae Malacosoma americanum (Eastern Tent Caterpillar)
Keywords: Equine abortion
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