Yesterday (Aug. 17), the Wyoming State Veterinary Laboratory posted a USDA release on its web site announcing the first confirmed U.S. case of vesicular stomatitis in 2006. The case, a 10-year-old horse, is located near Casper in Natrona County.

Donal O’Toole, MVB, MRCVS, PhD, Dipl. ECVP, FRCPath, director of the Wyoming State Veterinary Laboratory and head of the Department of Veterinary Sciences at the University of Wyoming in Laramie, reports federal authorities are examining additional suspect cases in the state.  Test results are pending. The last outbreak of vesicular stomatitis in the United States involved nine western states in 2005, and was formally declared over on April 11, 2006.

Vesicular stomatitis is a viral disease that primarily affects horses, cattle, and swine, but it can also affect sheep and goats. The disease causes blister-like lesions in the mouth and on the dental pad, tongue, lips, nostrils, hooves, prepuce and teats of livestock. When the blisters break, they can leave painful raw areas that can precipitate lameness and reluctance to eat.

The Wyoming laboratory doesn’t run samples on horses exhibiting clinical signs of vesicular stomatitis–that is under the purview of the USDA’s National Veterinary Services Laboratory, since VS is a foreign animal disease. Animals with VS can appear as if they’re suffering from a more serious problem–foot and mouth disease–so signs of vesicular disease in livestock are generally taken very seriously. Horses do not become infected with foot and mouth disease, so if there are horse and cattle affected with vesicular lesions on a premises, generally foot and mouth disease is not the cause