The U.S. Department of Agriculture is requiring that all horses classified as reactors for equine infectious anemia be quarantined at least 200 yards from healthy horses in livestock facilities under state or federal supervision.

“This amendment is part of our continuing effort to prevent the interstate spread of this serious disease,” said Joan M. Arnoldi, deputy administrator for veterinary services with the Animal and Plant Health Inspection Service, a part of USDA’s marketing and regulatory programs mission area.

Current regulations require regulated livestock facilities to place any EIA-reactor horse in a quarantined pen at least 200 yards from healthy horses, unless the reactor horse will be leaving the facility within 24 hours of arrival. The new rule would prohibit the intermingling of EIA-reactor horses and healthy horses for any period of time at these facilities.

EIA is a contagious, potentially fatal viral disease affecting equines, including horses, asses, mules, ponies, and zebras. It is generally spread by horse flies. About 1,600 horses in the United States test positive for EIA each year