One Confirmed Case, Additional Suspect Cases of VS in Wyoming

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.

"Vesicular stomatitis is an incredibly enigmatic disease, how it crops up out of the blue" said O'Toole. "It typically comes up out of the Southwest and moves north along riparian areas, and it starts jumping up through the states, and it's around this time of year that we typically see it...but we normally hear it's coming." That wasn't this case this year.

The VS-affected horse is on a quarantined premises with an additional 29 clinically normal horses and 25 clinically normal cattle. The affected horse has been isolated from the rest of the animals to ensure that troughs and feed buckets are not shared, and insect control measures have been increased. The horse hasn't been moved from the premises recently, and the owners reported a large burden of Culicoides midges and large numbers of biting flies in the area. These are thought to be possible carriers of the disease.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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