Botulism suspected in 100-horse euthanization in Fla.

Marion County, Fla.

-- More than 100 horses were euthanized earlier this month at the largest equine reproductive facility in the Southeast and state officials believe hay contaminated with the botulinum toxin may be to blame.

Horses at EquiTransfer, made up of two farms in Marion County totaling more than 80 acres, were fed hay supplied exclusively to that farm Oct. 4, according to Dr. Michael Short, a veterinarian with the Florida Department of Agriculture and Consumer Services. Within 12 hours, many of the horses were suffering symptoms of a neurological illness, including lethargy, weakness and respiratory distress, he says. Initially, investigators were baffled about the cause of the illnesses.

"As we learn more about what has happened to these horses, we are quite puzzled and, frankly, shocked at this sad situation," EquiTransfer says on its Web site. "We are in the process of completing a thorough analysis of every single daily routine at our practice, as well as products coming to us from each of our vendors."

Other horses that were not euthanized were treated with antibiotics and antitoxins, and a spokesperson for the farm says the health of the remaining horses on the farm is now stable.

While test results on the hay aren't expected back from University of Pennsylvania School of Veterinary Medicine for three to four weeks, Short says suspects the hay was contaminated with Clostridium botulinum.

"We're confident it's the hay, and we're confident it's not contagious," Short says. "It certain looks like the clinical signs [of botulism]."

The investigation now is focusing on EquiTransfer's hay supplier, who supplies the farm exclusively and contracts with another company for its baling. The presence of botulinum in the hay could have come from carcass contamination in the hay or soil. Since the contamination wasn't limited to only a few bales, Short says he is leaning toward tainted soil or some other.

Prior to the euthanization of the affected horses, EquiTransfer had a herd of about 400 mares. The facility completed more than 1,000 successful embryo transfers over the last two years.