Vesicular stomatitis outbreak heats up in three Southwest states

AUSTIN, TEX.— The caseload of vesicular stomatitis (VS) continues to climb as horses and cattle have now tested positive in Texas, New Mexico and Colorado.

Horses at 10 separate sites in Texas were recently confirmed to have VS, the first cases since 1998. Cattle at two ranches in Texas have also tested positive for VS.

Dr. John Romero, assistant state veterinarian for New Mexico, reported that 12 premises are under quarantine in the state, primarily focused in the Southeast region.

"One case in New Mexico is near Las Vegas and all cases are in horses," Romero says.

Romero predicts the disease will continue to appear throughout the summer months possibly in more northern areas. "There have been bigger outbreaks in the past and by no means is it a grave situation at this point," Romero says. "Feeding animals in separate containers and cooperating by reporting suspicious lesions will help matters," Romero says.

There have been no reports of the disease in wildlife or in animals other than horses and cows thus far.

"This is typically the time of year the disease spreads," says Dr. Keith Roehr, assistant Colorado state veterinarian. "Outbreaks tend to go in cycles, keeping quiet for three to five years," he says.

Signs of VS which include blisters or open sores in an animal's mouth, muzzle, tongue, nostrils, teats or hooves are similar to those that appear with foot and mouth disease (FMD), although horses are not effected by FMD.

"In past years, animals have died, but there haven't been any deaths yet this year," Roehr explains.

The primary concern with VS is the loss of milk production in dairy cattle.

"Vesicular stomatitis can be devastating to dairy farmers, cows can develop mastitis and production levels drop significantly," Roehr says.

Veterinary bills in correlation with loss of use of horses tend to be the largest concern of farmers and ranchers, Roehr says.

The viral disease is transmitted through phlebotomine sand flies and black flies. Once VS is introduced to a herd, the disease spreads from animal to animal through contact or exposure to saliva and ruptured lesions.

Animals showing signs of VS and those that may have been exposed to the disease are quarantined for 30 days after all blisters on effected animals have healed. A state veterinarian then examines the animal(s) to give them a clean bill of health.

Treatment for VS is limited to quarantine, supportive care and in some instances antibiotics, Roehr says, but loss of use can really hit owners' pockets.

Animals living in river valleys where fly populations are high tend to contract the disease more readily than in other areas.

Humans can contract VS when handling infected animals if proper safety methods are not exercised. People that contract VS exhibit influenza-like illness with symptoms such as fever, muscle aches, headaches and malaise.

Incubation of VS ranges from two to eight days. Excessive salvation is often the first sign of the problem, followed by increased body temperature, followed by the appearance of lesions or blisters.

Suspected cases should contact a USDA Veterinary Service's office.