ESPN.com - Horse Racing - Researchers focus on proving theory in foal deaths

Horse Racing
NTRA Polls
Race Results
Results Ticker™
Live Racing
Money Leaders
Schedule
Breeders' Cup
Daily Racing Form
AQHA Racing
Virtual Racing
Message Board
SPORT SECTIONS
 
Wednesday, May 30
Researchers focus on proving theory in foal deaths




LEXINGTON, Ky. - After pinpointing a naturally occurring cyanide in the deaths of more than 500 foals in Kentucky's horse country, scientists are now focused on proving their theory and preventing a future outbreak.

"We've come a long way in a fairly short period of time, but there's still a lot of things we don't understand," said Dr. Thomas Tobin, a toxicology and pharmacology researcher at the University of Kentucky's Gluck Equine Research Center.

The prevailing theory in the deaths of the foals and thousands of aborted fetuses suggests that mares somehow ingested cyanide produced from the leaves of cherry trees, which are common on many horse farms.

But how the mares ingested the poison remains unclear, as well as how the chemical was produced in such deadly quantities.

Scientists have speculated that several days of hard frost may have damaged the leaves and made them even more toxic.

Researchers and veterinarians began surveying more than 150 farms on Wednesday to determine the exact conditions present on the farms during the last few weeks of April. The statistical data collected then will be analyzed by local scientists as well as those at the United States Department of Agriculture.

The on-site visits also will focus on the proximity of cherry trees to pastures in which pregnant mares may have grazed.

"It wouldn't take a large amount of poison to affect an early-term embryo or a near-term foal," Tobin said. "We know that wilted leaves or broken branches from a black cherry tree are lethal to cattle and sheep."

Low levels of cyanide, which inhibits the body's ability to receive and use oxygen, were found in the tissue of several fetuses. The poison may have caused foals to struggle for oxygen inside the womb.

Scientists also believe that Eastern tent caterpillars, which nest in the cherry trees and are immune to the poisonous chemicals in the leaves, may have played a role.

Tent caterpillars, which in Kentucky have now cocooned and are growing into moths, will be shipped from New York for study. Researchers will feed cherry tree leaves to caterpillars and monitor how the insects digest the toxins and how the toxins might be secreted and ingested by horses, Tobin said.

"We expect to have significant data from those tests back in about six to eight weeks," he said. "We hope they will be able to tell us exactly what, if any, part the caterpillars played in this scenario."

Scientists originally thought toxins generated by fungal- or mold-based agents in pasture grasses might have been behind the outbreak. But tests on hundreds of grass samples have been mostly negative.

Up to 5 percent of this year's foal crop and as much as 29 percent of the 2002 crop may have been lost to what has become known as Mare Reproductive Loss Syndrome.

The numbers are based on estimates of approximately 500 dead foals this year and 2,000 spontaneous abortions of horses that would have been born next spring.

Kentucky produces about 10,000 thoroughbred foals each year. David Switzer, executive director of the Kentucky Thoroughbred Association, estimated the economic impact on the state's billion-dollar thoroughbred industry at between $200 and $225 million.

The foals lost this year would have generated about $37 million in stud fees and sales revenue, and those lost that would have been born next year about $150 million, Switzer said.

"It's going to trickle down and hit everyone connected with the horse industry," he said. "Nobody is going to be untouched."

Send this story to a friend | Most sent stories