According to veterinarians, there are two possible reasons why there have been no reported cases of equine vesicular stomatitis (VS) this year. The first possible reason is that there is actually no disease occuring, the second, is that there might be cases of VS out there, but they remain unreported.

Factors inherent in the virus or in the host population in this year might have affected the absence of the disease in the Southwest this year. These factors range from environmental to ecological, possibly even meteorological. Variables within the virus itself, having to do with how, when, where, and why the infection is hosted, also could be the cause of the apparent absence of the disease.

A touchier subject is the possibility that there are cases of EVS progressing in horses around the country, but are unreported, for reasons ranging from the horse owner not recognizing the onset of the disease to farms fearing the economic repurcussions of a quarantine. “Legally, owners don’t have to report–the veterinarians do,” said Colorado State University Research Associate, Elizabeth Mumford, DVM, MS.

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