Nine months of investigation has produced information negating the earlier conclusion that cyanide poisoning caused the epidemic of mare reproductive loss syndrome in Kentucky and surrounding states in the spring of 2001. A Clemson University research team headed by Dee Cross, Ph. D. and Sam Gray, graduate student, has identified poison hemlock as the probable cause, stating a "less than a one in 10,000 chance that poison hemlock was not related to that problem."
They found the correlation to cherry trees only moderate and began to investigate everything growing along the fence rows. They then went back and checked the farms and pastures involved and found a very high correlation.
They found that almost every problem pasture did indeed have poison hemlock in fence rows or tree enclosures. They documented evidence that the mares had actually eaten the plant through finding bite marks on the stems. They discovered that the hemlock was only available to mares in "back pastures" that were less well groomed or had wire fences that weedeaters could not get under.
Then they consulted with USDA researcher Kip Panter, Ph. D., the nation's leading authority on poison hemlock. Dr. Panter confirmed that the plant causes abortions and birth defects in livestock, though no specific research had been done concerning its effect on pregnant mares.
The weather is still considered a co-conspirator in MRLS because of the compounding effects of an early spring with lush and tender greenery hanging over or through the fences followed by a freeze and then snow covering the available grass. The freeze caused the abortion-causing chemical in the hemlock to spike and the snow cover made the mares more likely to try the usually unpalatable hemlock. Another side effect is that alkoloids in poison hemlock cause addictive reactions in animals similar to nicotine's effect on humans. Once they start eating it, they are likely to continue.
Other researchers have been consulted, including David Powell, B. V. Sc., who worked on this same phenomenon for the University of Kentucky's Gluck Equine Research Center. He says the data is inconclusive.
Research continues; however, reproducing the disease is difficult. Cross has applied for a $70,000 grant to continue the research.
More information will be added as it becomes available.
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