More time, more foals and still no explanation


LEXINGTON, Ky. – Researchers have yet to determine an exact cause or cure for mare reproductive loss syndrome that is plaguing horse breeders in Kentucky, Ohio and bordering states.

As of May 21, the number of aborted fetuses and dead foals submitted for testing to the Kentucky Livestock Disease Diagnostic Center since April 28 broke the 500 mark at 528.

Researchers at University of Kentucky’s Maxwell H. Gluck Equine Research Center and the UK Livestock Disease Diagnostic Center are running many different tests to determine the cause of the losses.

One of the leading theories about the cause of the foal deaths and lost pregnancies involves toxins produced by molds or fungi.

Researchers are requesting samples from first cuttings of hay made before May 5 to test for levels of mycotoxins in the pastures. It is not known if or how first cutting hay is involved, but the hay samples will give a picture of pasture makeup at this time.

70 foals lost.

Jim Archer, a Belgian and Percheron breeder from Caldwell, Ohio, said the mare reproductive loss syndrome is not anything new to him. The Noble County farmer has lost 70 foals in the last 10 years to fescue toxicity.

“I always said it wouldn’t be considered a problem until it affected some of the big money breeds,” said Archer. “It’s been a problem for a long time, it just hasn’t been reported.”

Archer says he believes the weather plays a large role in the level of mycotoxins in the fescue.

“I keep pretty good records and in my worst loss years, the weather conditions have been very similar,” Archer said.

Buying binders.

Horse breeders are encouraged to feed mycotoxin binders, which bind mycotoxins in the animal’s digestive tract, preventing those toxins from being absorbed.

The binder can usually be found at feed stores and can be added to your regular feed. The binders come in a variety of sizes of pails and bags, ranging in price from $8 to $32.

According to Doug Davis, sales manager for Gerber and Sons Inc. in Baltic, Ohio, there are several binding agents on the market that bind mycotoxins and render them somewhat inactive, but they are not 100 percent effective. Some of the brand names are Condition-ade, Sodium Bentonite, Diabond, MTB100 and Novasil.

“Cost per head per day varies, but it is usually in the 31/2 to 8 cents per head per day range depending on the amount fed,” Davis said. “You would typically feed 3 to 7 ounces a day, depending on the size of the animal.”

Gerber and Sons carries 50-pound bags of Condition-ade for about $9. The company also sells Sodium Bentonite and MTB100.

“Anytime you suspect you are feeding moldy feed, you should be on a binder,” said Davis.

Other problems.

Along with early fetal loss and late-term abortions, horse owners are also seeing an increase in pericarditis – or excess fluid in the sac around the heart – eye inflammation and hoof problems in just about every breed, sex and age of horse.

Preliminary findings indicate the presence of zearalenone, an estrogenic toxin that can be produced by a mold on grass. This compound has been shown to cause reproductive, cardiac and eye problems in horses and other species.

“We are not sure if the problems are related to the foal loss, but it is a good possibility,” said Rusty Ford, Kentucky Department of Agriculture’s equine program manager. “We’re still investigating and waiting on more toxicology reports.”

Kentucky scientists are testing blood and urine samples taken from the mares, tissue from the dead foals, pasture grasses and more, including tent caterpillars.

Caterpillars tested.

Tent caterpillars tested positive for zearalenone, but Gluck Center scientists are unsure of the significance and are awaiting more test results. The caterpillars tested negative for cyanide.

Researchers are also testing endophytes such as those in fescue, estrogen-like substances in plants, and other compounds.

Tom Tobin, a veterinary pharmacologist/toxicologist at the Gluck Center, is asking breeders to bring in frozen colostrum from mares with losses and normal mares collected after April 17. Tobin’s laboratory is also testing samples of first cutting Kentucky-raised hay made prior to May 5.

Ohio testing.

While testing in Kentucky is free, Ohio owners must pay $50 to have their fetuses or foals tested at the Ohio Department of Agriculture’s Animal Disease Diagnostic Laboratory. The $50 analysis includes necropsy, a bacterial culture, virologic testing, and serologic testing.

Usually the horse owners pay $100 for the test, but the fee was reduced May 18 for 30 days. The test usually costs the lab $300 to $400.

Ohio horse owners should submit aborted fetuses and deceased foals with the placenta for testing. Pasture samples should also be tested to identify any endophytes or mycotoxins.

To date, the laboratory has not received an unusally high number of foals or fetuses.

Owners and veterinarians can reach the Ohio Animal Disease Diagnostic Laboratory at 8995 E. Main Street, Reynoldsburg, OH 43068; or at 614-728-6220.

Losses have been reported in Highland, Vinton, Jackson, Gallia, Meigs, Athens, Washington, Morgan, Scioto and Geauga counties in Ohio. There have also been losses reported in Pennsylvania and West Virginia.

Horse farm owners and managers and others with comments, questions or ideas about mare reproductive loss syndrome can call the Gluck Center at UKY-257-MARE (859-257-6273) or visit its Web site at

Economic impact.

In Kentucky, the mysterious malady has killed an estimated 4.5 percent of this year’s foal crop and caused abortions in up to 20 percent of the mares carrying next year’s crop.

Many believe Kentucky’s breeders face a loss of over $250 million. However, those with a bred horse who survives the foal crisis could command a huge price to balance the loss.

(Reporter Annie Santoro can be reached at 1-800-837-3419, ext. 22, or

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