Colorado has added seven new equine vesicular stomatitis (VS) premises to its current count and two new bovine VS premises since the beginning of August, according to the USDA’s latest VS Situation Report. The disease was reported on 22 new equine premises and five new bovine premises in Utah in that seven-day period. Arizona, New Mexico, and Texas have not reported any new VS-positive premises.

Vesicular stomatitis is a sporadic infectious viral disease characterized by blister-like lesions in the mouth and on the lips, nostrils, teats, and coronary bands. How the disease spreads is not fully known; insect vectors and movement of animals could be responsible. Signs of the disease can last from seven to 10 days. The horse might lose weight drastically, but usually will gain it back after oral lesions heal. Clinical signs of the disease have been reported to appear three to 14 days after exposure to an affected animal.

According to the Aug. 8 report, Hinsdale and Montezuma Counties in southwest Colorado are affected for the first time in 2005, bringing the total number of infected counties to seven (other counties include Delta, La Plata, Mesa, Montrose, and Rio Blanco). There are 15 positive equine species and 11 positive bovine species. Seven of these premises are on their 21-day quarantine-removal countdown, which begins after the final lesion on the last affected animal heals.

The Horse cited a newspaper on July 18 that reported VS in Montezuma. Richanne Lomkin, DVM, a field veterinary medical officer for the USDA , explained why news reports might say that a county is affected when the county isn’t on the USDA list of affected counties until much later: “We have to make absolutely sure by a blood sample that we truly do have a positive case (before making it an official affected premise),” she says. “However, if clinical signs make veterinarians suspicious of VS, the premises will be quarantined whether or not the positive blood samples have been returned yet