Volume 5, Number 21 - August 18, 2005
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Two cases of VS confirmed
Two Sublette County cattle herds have been found to containanimals infected with vesicular stomatitis and are currently under quarantine, according to Wyoming State Veterinarian Dr. Dwayne Oldham.
Oldham said that a Boulder-area producer noticed one of hiscows slobbering and going off her feed. A local veterinarian was called in and the diagnosis confirmed on Aug. 10 by the Foreign Animal Disease Diagnostic Laboratory on Plum Island, NY. The herd of 250 head of cattle, all on privat eland, was placed under quarantine, as were 27 horses on the premises.
A second case was confirmed on Monday, Aug. 15. This was on a neighboring ranch; separation of the two herds is a ccomplished via a fenceline.
Wyoming now has three VS cases, with two in this county and a third involving a horse at the Goshen County Fairgrounds that also tested positive for the virus.
Six new equine vesicular stomatitis positive premises and four new bovine vesicular stomatitis premises were also identified in Colorado. Three of the new equine positive premises were located in new Colorado counties, Archuleta, Larimer and Moffat.
Other states with recent VS cases include New Mexico and Utah.
VS is a viral disease that primarily affects horses, cattleand swine and occasionally sheep, goats, llamas and alpacas, according to the USDA Animal and Plant Health Inspection Service, veterinary services division. Humans can also become infected with VS when handling affected animals, but this is rare. VS has been confirmed only in the western hemisphere.
Outbreaks in the Southwestern United States usually occur during warm months, often along waterways and in valleys. The Southwest experienced a VS outbreak from May 2004 through January 2005. Animals inTexas, New Mexico and Colorado were involved. A total of 294 premises in 43 counties were affected in these three states.
In affected livestock, VS causes blister-like lesions to form in the mouth and on the dental pad, tongue, lips, nostrils, hooves and teats. These blisters swell and break, leaving raw tissue that is so painful that infected animals generally refuse to eat or drink. If the hooves are affected, the animal may show signs of lameness. Severe weight loss usually follows and in dairy cows a severe drop in milk production commonly occurs. Some affected dairy cattle can appear to be clinically normal and will continue to eat about half of their normal feed intake. Lesions in horses may also be expressed as crusting scabs on the muzzle, lips or ventral abdomen.
How VS spreads is not fully known; insect vectors, mechanical transmission and movement of animals are all factors. Once VS is introduced into a herd, the disease may move from animal to animal by contact or exposure to saliva or fluid from ruptured lesions.
VS is recognized internationally as a reportable disease.What this means is that there are serious economic and regulatory repercussion sassociated with the diagnosis, and once the disease is detected in the United States, many countries take action to block international trade of U.S. animals. Interstate movement of animals is also impacted. Premises containing affected animals are quarantined until 21 days after the lesions in the last affected animal have healed. Quarantine periods may be quite long.
While VS can cause economic losses to livestock producers, it is a particularly significant disease because its outward signs are similar to (although generally less severe than) those of foot-and-mouth disease, a foreign animal disease of cloven- hoofed animals that was eradicated from the United States in 1929.
In affected livestock, the incubation period for VS ranges from two to eight days. Often, excessive salivation is the first sign that ananimal is affected. Body temperature may rise immediately before or at the sametime lesions first appear. Initially, close examination of the mouth reveals blanched and raised vesicles.
There is no specific treatment or cure for VS. Good sanitation and quarantine practices on affected farms usually contain the infection until it dies out of its own accord.
The morbidity rate for vesicular stomatitis varies considerably within species. For example, about 5 to 10 percent of affected herds generally show clinical signs of the disease. If there are no complications such as secondary infections, then affected animals recover in about two weeks. VS does not generally cause animals to die.
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