Florida Farm & Feed

Cyanide Cited in Ky. Foal Deaths

From the Associated Press

(May 24, 2001)

LEXINGTON, Ky. (AP) - Cyanide occurring naturally in black cherry trees is the apparent cause of more than 500 foal and fetus deaths on central Kentucky farms this spring, scientists said Thursday.

But while scientists believe they have identified cyanide as the toxin affecting horses and cherry trees as the source, part of the mystery remains.

"Precisely how delivery to the mare occurs is unclear," Thomas Tobin, a professor at the University of Kentucky Gluck Equine Research Center told several hundred horse breeders, farmers and owners at a meeting at the Keeneland sales pavilion.

The leading theory implicates the Eastern tent caterpillar, however.

"There is an extremely close association between the presence of the cherry trees, the presence of the Eastern tent caterpillars and both early fetal losses and late-term abortions," said Dr. Jimmy Henning, a University of Kentucky agronomy professor. "We have to conclude the wild cherry-caterpillar complex is the lead suspect in the Mare Reproductive Loss Syndrome."

Henning said tests have failed to support other hypotheses as to the cause of the outbreak, which began in late April.

Tobin said the caterpillars are immune to cyanide from the black cherry tree, and one theory is that the mares could have ingested fecal matter from the caterpillars.

"Observations to date implicate cyanide as the causal agent," University of Kentucky College of Agriculture Dean Scott Smith said. "We want to emphasize that the current observations are preliminary, must be confirmed, and that further validation is absolutely essential. We have not yet met reasonable standards of scientific proof. A great deal of work needs to be done."

For the past three weeks, scientists been trying to determine why foals are being born sick or dying and why mares are aborting early term pregnancies on farms throughout central Kentucky.

Only 24 deaths have been reported since Sunday and only four in the past two days. More than 500 deaths were reported between April 28 and May 19.

"It's slowed down tremendously," said Dr. Bill Bernard, internal medicine specialist at Rood and Riddle Equine Hospital. "It's near the end of the breeding season, so there's fewer mares left to foal, but it's still encouraging."

David Powell, equine epidemiologist for the University of Kentucky's Gluck Equine Research Center, said he feels safe advising owners and farmers to put their horses back out to pasture with no fear of the illness reappearing.

"I think that whatever it is we're looking for has already left town," said Gus Koch, manager of Claiborne Farm.

Powell said even if the cause is never pinned down, the crisis has had some positive effects.

"Right now, there's just very little data about horses and the risk of exposure to these various toxins," he said. "What we're into at the present time is very pioneering. We're generating much of this information for the first time as we go along.

"We're going to continue studying this problem until we find an answer and beyond. No matter what happens from here on out, I don't think anyone will be caught off guard by something like this ever again."

Farmers don't expect another outbreak any time soon.

"This was a very rare happening. If our climate or our grasses or our methods were so fickle that we were going to have problems like this, we would've been out of business a long time ago," Koch said. "I'm not at all worried about this happening all over again."

David Switzer, executive director of the Kentucky Thoroughbred Association, said Wednesday farmers still have hopes of salvaging this foaling season, which runs through June.

"We're not even thinking about next breeding season. We're still focusing right now on getting mares in foal for the 2002 crop," Switzer said. "We'll keep proceeding forward and look for whatever the cause of this is. Once we do that, we'll all march right into 2002 with all the confidence in the world that this is not going to return."