Natural Cyanide May Be Killing Foals

ByABC News
May 25, 2001, 10:03 AM

L E X I N G T O N, Ky., May 25 -- A naturally occurring cyanide produced from the leaves of black cherry trees may be responsible for the deaths of hundreds of central Kentucky foals this spring, researchers say.

The theory hasnt been confirmed, and it isnt clear how thepoison got into the pregnant mares, but observations implicatecyanide as the cause of more than 500 foal deaths and abortedfetuses, University of Kentucky College of Agriculture Dean ScottSmith told breeders and farmers Thursday night.

This springs large infestation of Eastern tent caterpillars,which feed on cheery tree leaves, may have played a role intransferring the poison, scientists said.

We have to conclude the wild cherry-caterpillar complex is thelead suspect in the deaths, said Dr. Jimmy Henning, a Universityof Kentucky agronomy professor.

One theory is that the mares ingested the caterpillars fecalmatter, which contained the cyanide, said Thomas Tobin, a professorat the University of Kentucky Gluck Equine Research.

Scientists have been scrambling to find answers to explain whyfoals have been dying and mares have been losing fetuses at astaggering rate this spring. The mystery has sent fear through thestates $1.2 billion thoroughbred industry, which produces about athird of the nations foals each year.

Clues Hard to Come By

Tests have failed to support other hypotheses about theoutbreak, Henning said. Blood samples showed no evidence ofinfectious or contagious diseases, and early samples from pasturegrasses provided no clues.

The deaths havent been uniform across the region either. Somefarms havent reported any unusual stillbirths or miscarriages,while others have reported miscarriage rates of 10 percent to 75percent.

A similar unsolved outbreak occurred in 1981, a year withweather similar to this years, with a warm, dry spring followed byseveral hard freezes and subsequent dry weather.

It replicates in mirror image the month of April back in 1981,when history relates a very similar syndrome, said David Powell,equine epidemiologist for the Gluck research center.