The nation’s first case of vesicular stomatitis (VS) for 2009 has been detected in a horse in Starr County, in far south Texas. VS is a sporadically occurring virus that is endemic to the U.S. Signs of the disease include blisters, lesions and sloughing of the skin on the muzzles, tongue, teats and above the hooves of susceptible livestock, which include horses, cattle, sheep, pigs, deer and some other species of animals.

“The most recent outbreak was in 2006 limited to Wyoming only, where 17 horses and a dozen cattle on 13 premises were confirmed to have the virus,” said Dr. Bob Hillman, Texas’ state veterinarian and head of the Texas Animal Health Commission (TAHC), the state’s livestock and poultry health regulatory agency. “To prevent the spread or introduction of infection, many states and countries will place additional entry requirements or restrictions on the movement of animals from affected states, or portions of the state. Call the state or country of destination before moving livestock, to ensure that all entry requirements can be met. Do not risk shipments being turned away, or worse, spreading disease and facing legal action by animal health authorities.”

“Often horses are the signal, or first, animals to be confirmed with vesicular stomatitis when the virus is active. If the blisters and lesions are seen in cattle, sheep, pigs or other cloven-hooved animals, our first concern is a possible introduction of foot-and-mouth disease, the most costly and destructive foreign animal disease. Horses are not susceptible to foot-and-mouth disease, but anytime blisters or unusual sores are seen, animals should be examined by a veterinarian as soon as possible.”

“Move sick animals away from the remainder of the herd to protect against disease spread,” urged Dr. Hillman. “Do not move sick animals from the premises, and call your veterinarian or the nearest Texas Animal Health Commission area office, or the Austin headquarters at 800-550-8242. Laboratory testing to confirm infection can be run at no charge to the livestock owner.

“Vesicular stomatitis is painful for affected animals, but usually, the lesions will heal within two weeks to a month. For some severe cases, owners may elect to have an infected animal euthanized, to put an
end to the suffering. In dairies, VS infection can lead to a substantial loss of production,” said Dr. Hillman. Treatment of VS-infected animals consists of supportive care, and antibiotics may be needed to prevent secondary infections in the open sores. Animal health officials in nearly all states, including Texas, require VS-infected animals and their herd mates to be quarantined until at least 21 days after all lesions have healed. A follow-up examination of the animals by the state veterinarian’s office is required prior to quarantine release.

VS outbreaks are extremely sporadic, and years may lapse between cases. Sand flies and black flies are thought to play a role in the virus transmission, so controlling insects is important. In 2005, the VS outbreak involved livestock on at least 445 premises in nine states, including Arizona, Colorado, Idaho, Montana, Nebraska, New Mexico, Texas, Utah and Wyoming. In 2004, affected animals were detected in eight counties each in Texas and New Mexico and in 22 Colorado counties. Before the 2004 outbreak, VS had been “silent” since 1998, when Arizona, Colorado, New Mexico and Texas had cases.

More information about VS and a map showing the location of Starr County in Texas are available on the TAHC web site at: http://www.tahc.state.tx.us.