Arizona Department of Agriculture officials today announced that experts from the U.S. Department of Agriculture, Animal Plant Health Inspection Service, Veterinary Services, have joined the investigation into a series of horse deaths near Ash Fork, located west of Flagstaff on Interstate 40. The USDA team arrived in Phoenix after an invitation from the Arizona Department of Agriculture Office of the State Veterinarian.

Since August 1998, approximately 13 horses and a mule have died after displaying similar symptoms. The cause of the illness has not been determined, although animal health experts working on the cases have mostly ruled out infectious agents. Arizona Department of Agriculture investigators still believe the case is probably isolated to the Ash Fork geographic area and horse owners do not have reason to fear a horse-to-horse transmittal of whatever is causing the animal deaths there. Due to the clinical signs and the apparent absence of an infectious agent, the investigation has primarily focused on botulism or other toxic agents as the possible cause of the horse deaths.

The joint diagnostic team includes an Arizona Department of Agriculture state veterinarian, two diagnosticians, two pathologists and an epidemiologist, as well as a scientist from the Arizona Veterinary Diagnostic Laboratory at the University of Arizona in Tucson.

“We are pleased the U.S. Department of Agriculture was willing to help in this investigation,” said Sheldon R. Jones, Arizona Department of Agriculture director. “Their expertise in similar cases throughout the United States has proven very helpful in identifying the cause of animal health problems