Florida Farm & Feed

Foal Deaths May Remain Mystery

From the Associated Press

(May 25, 2001)

LEXINGTON, Ky. (AP)

- Twenty years ago, pregnant mares on central Kentucky horse farms began spontaneously aborting their fetuses in unsettling numbers.

Weeks of research and detailed testing never provided a conclusive cause behind the problem or how to prevent it.

Now, with the state's billion-dollar thoroughbred industry facing a similar but even more devastating crisis, some experts concede they again could be left with more questions than answers.

"The bottom line is that we still don't know what is behind this, and we may never know," said Dr. Doug Byars, internal medicine specialist at the Haygard-Davidson-McGee clinic in Lexington. "We have lots of pieces of the puzzle. They just don't want to fit together to give us a clear picture of what we're dealing with."

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

They've come up with several theories, including environmentally spawned grass toxins, cherry trees and Eastern tent caterpillars. They have settled on very few concrete answers.

They are convinced only that the mysterious illness, termed Mare Reproductive Loss Syndrome, is not viral or contagious in nature.

"When this type of syndrome has occurred in the past, it has been virtually impossible to come up with a diagnosis," Dr. David Powell, an equine epidemiologist for the University of Kentucky's Gluck Equine Research Center, said Wednesday. "The reason for that is that we haven't become aware of the problem until the event has passed.

"When you're forced to look at something in retrospect, much of the evidence that would be helpful in determining the cause of that problem is no longer available. That makes it extremely difficult to come up with definitive answers."

That was the case two decades ago, when farm owners and managers noticed an increased number of mares were losing their early-term pregnancies.

"We did have similar incidents in 1980 and 1981, but it was nothing of this magnitude," said Dr. Bill Bernard, internal medicine specialist at Rood and Riddle Equine Hospital in Lexington. "In those cases, it was only a limited number of farms and a much smaller number of horses that were affected."

According to Powell, the 1980 and 1981 outbreaks involved only mares in the early stages of pregnancy and did not include an increase in sick or dying full-term foals. Mares that had been checked at around 35 days later were found to be inexplicably empty at between 45 and 60 days, he said.

In comparing the two outbreaks, Powell noted several similarities.

"The same extreme weather conditions prevailed in 1980 and 1981 as they did in 2001: unusually warm temperatures followed by frost and then drought and more warm temperatures," he said. "We also noted heavy infestations of tent caterpillars in both of those previous years, just as we've seen this year.

"The fact that both of those unusual circumstances were present in years when there has been this type of incidents leads us to believe that one or both might somehow be related. How or why they are related and to what degree, that's what we're trying to determine."

David Switzer, executive director of the Kentucky Thoroughbred Association, said it is critical that a concrete cause be found, no matter how much time or research is needed.

"It's important not only for preventative purposes, but to allay the fears of those who do industry business in the state of Kentucky," said Switzer, who conservatively estimates the syndrome will cost those directly involved in the industry - owners, breeders and boarders - as much as $200 million.

Powell is hopeful the intense effort poured into finding a cause will help prevent such a catastrophic event in the future.

"We've put tremendous resources, including personnel and expertise, into investigating this outbreak, and I do feel that over a period of time we will come up with some answers," Powell said. "What I'm not willing to speculate at this stage is when we will have those answers."

Byars, however, isn't so sure they'll ever settle on a definitive cause. "Obviously, everybody is hopeful we'll nail this thing down, but it wouldn't shock me if we didn't," he said. "We may end up narrowing down the conditions that were responsible and documenting its effects, but never find a cause.

"Maybe it's just Mother Nature making sure we don't get too comfortable. Unfortunately, we just may never be sure."             ¶