State veterinary officials say a mystery illness has killed nearly 100 horses at one farm in central Florida.

As many as 100 horses have died in just over a week in Marion County, an area known for its hundreds of horse farms. The cause of the illness is unknown.

The owners of the farm think contaminated hay wreaked havoc on the animals' nervous systems.

Samples have been sent to toxicology labs to determine what caused the illness on this one farm.

Necropsies were performed on two horses at the University of Florida Veterinary Medical Center. But those reports failed to find an apparent cause of what sickened the horses.

There are at least 400 horses on the EquiTransfer farm.

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