The first case of what state officials suspect to be botulism was seen in the latter part of November, 1998. To date, 13 horses in the Ash Fork, Ariz., area, a rural town west of Flagstaff, have exhibited the same neurologic symptoms and have been euthanized. According to Robert Glock, DVM, PhD, Dipl. ACVP, Director of the Diagnostic Laboratory at the University of Arizona, some of the affected horses have been necropsied at the University of Arizona and tissue samples from additional affected horses have been tested there. All tests were negative for botulism. Glock added that mice have been injected with serum from these horses and the results continue to be negative for botulism. Tissue samples from the affected horses also have been sent to the University of Pennsylvania’s New Bolton Center for further testing. At press time, the test results from the New Bolton Center were not available.

Tim Cordes, DVM, of USDA, APHIS, said there have been “lots of activity that suggest botulism.” To address the situation, the USDA has created an emergency response team that will include two pathologists, two epidemiologists, and a support person. The emergency response team will hold daily teleconferences with USDA officials in Washington, D.C., to report on progress being made in this situation.

While the botulism hasn’t been confirmed, Glock stressed that botulism is hard to detect in dead animals. Glock cautioned the source of botulism can be difficult to determine. At this point, there is no definitive diagnosis for the condition that exists in Arizona.

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