Caution for livestock owners

May 11, 2012
by WLJ
—Vesicular stomatitis confirmed in New Mexico

The nation’s first 2012 confirmed cases of vesicular stomatitis (VS) was announced on May 1 in New Mexico; two horses outside of the town of Tularosa, NM, have been found to have lesions caused by VS. Western livestock owners are warned to take added precautions due to the proximity of the virus.

“Vesicular stomatitis can be painful for the animals and costly to their owners,” said State Veterinarian Dr. Keith Roehr. “While this virus does not typically cause death, the animal can suffer from painful sores so it is important to monitor herds for symptoms.”

VS is a foreign animal disease that occurs sporadically in certain areas of the western U.S. Index cases are typically seen in Texas, New Mexico or Arizona. The last confirmed case of VS in Colorado was in 2006. Veterinarians and livestock owners who suspect an animal may have VS or any other vesicular disease should immediately contact state or federal animal health authorities. Livestock with symptoms of VS are isolated until they are cleared through the USDA’s diagnostic laboratory testing. There are no USDA approved vaccines for VS.

While rare, human cases of VS can occur, usually among those who handle infected animals. VS in humans can cause flu-like symptoms and only rarely includes lesions or blisters.

VS signs and transmission

VS-susceptible species include horses, cattle, sheep, pigs and deer, among others. The clinical signs of the disease include vesicles (liquid-filled blisters), erosions and sloughing of the skin on the muzzle, tongue, teats and above the hooves of susceptible livestock. Vesicles are usually only seen early in the course of the disease.

As the disease progresses, the ruptured vesicles erode to produce lesions where the top tissue layers sloughs off. Animals with oral lesions may refuse to eat and/or drink due to discomfort, which results in weight loss. Coronary band lesions can result in lameness in one or more feet. In severe situations, the hoof may slough or hoof growth may be permanently impacted.

The transmission of VS virus is not fully understood. Most cases are likely spread by insect vectors, particularly along river valleys. Biting flies have been shown, both in natural and experimental infections, to be capable of transmitting VS. Sand flies and black flies have been identified as important species in the transmission of VS.

Tips for livestock owners

Strict fly control is an important factor to inhibit the transmission of the disease.

Avoid transferring feeding equipment, cleaning tools or health care equipment from other herds.

Livestock owners should contact the state of destination when moving livestock interstate to ensure that all entry requirements are met.

Fairs, livestock exhibitions and rodeos may institute new entry requirements based on the extent and severity of the current VS outbreak. Be sure to stay informed of any new changes to event requirements.

For additional information, contact your state veterinarian or your local Extension office. — WLJ