Foal Deaths Alarm Bluegrass State

Scientists are trying to figure out why pregnant Kentucky mares are losing foals at a staggering rate this spring in a mystery that has sent fear through the state’s $1.2-billion thoroughbred horse industry.

“It’s got a lot of people spooked, no doubt about it,” said Steve Johnson, president of the Kentucky Thoroughbred Farm Managers Club. “I’ve talked to a lot of farm owners who aren’t going to sleep very much until they find out what is going on with their mares.”

So far, most tests for toxins or viruses have come back negative. Kentucky’s famous bluegrass may even be a factor, and some horse owners are sending their mares out of the state until the mystery is solved.

The number of unexplained stillborn foals and spontaneously aborted pregnancies is nearly seven times normal in central Kentucky this spring.

From April 28 through last Monday, the University of Kentucky Livestock Disease Diagnostic Center received 318 miscarried fetuses or stillborn foals for testing. It received just 46 during the same period last year.

Some farms have not reported any unusual stillbirths or miscarriages, while others have reported miscarriage rates of 10% to 75%.

“There’s a lot of rumors going around, and no one is really sure what to believe at this point,” said Three Chimneys Farm manager Dan Rosenberg. “I think the thing that frightens people the most is that we really don’t know why this is happening.”

Claiborne Farm manager Gus Koch said one of his mares had a stillborn foal last week. Over the weekend, he discovered that 10 more mares, which were early in their pregnancies, had aborted their fetuses.

“I’ve never seen anything like this. Statewide and industry-wide, it could be devastating,” he said.

Kentucky leads the world in thoroughbred breeding, with more than 20,000 mares bred last year alone. Breeding season normally fills horse owners with optimism, evoking images of foals frolicking over lush green pastures and colts thundering down the stretch in the Kentucky Derby.

A team of more than two dozen scientists, veterinarians and farm managers has concluded that the deaths are probably related.

“So many farms having problems over such a narrow period of time indicates that there is a common source,” said David Powell, a disease researcher with the University of Kentucky’s Gluck Equine Research Center.

But Powell said the problem is not believed to be spread from one horse to another, unlike the outbreak of foot-and-mouth disease in Europe.

One theory is that Kentucky’s warm, dry spring followed by several hard freezes allowed a fungus or toxin to develop in grasses eaten by horses. Powell and others are telling farms to mow frequently and limit horses’ time in pastures.

Other possible theories involve bacteria or chemicals.

The research team has sent out a detailed questionnaire to gauge the extent of the problem and determine common factors. Blood, tissue, grass and soil samples are being examined.

“You won’t find anywhere else in the world with as many equine experts equipped to study this sort of problem,” Rosenberg said.

“I’m confident that we’ll know fairly soon what’s causing this and what can be done to prevent it. Until then, all we can do is hold our breath and hope for the best.”