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Livestock Health Warning Has Been Issued

Posted 8/6/2009

The nation’s first case of vesicular stomatitis (VS) for 2009 has been detected in a horse in Starr County, in far south Texas. “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.”

What is Vesicular Stomatitis (VS)? Vesicular stomatitis is a viral disease that primarily affects horses, donkeys, mules, cattle, and swine. This disease also occasionally affects sheep and goats. Many species of wild animals, including deer, bobcats, goats, raccoons, and monkeys, have been found to be susceptible hosts.

Symptoms are usually evident in 2 to 8 days after infection. Symptoms will include; excessive salivation as the first sign. Body temperature may rise immediately before or at the same time that blister-like lesions first appear in the mouth and 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 and show signs of lameness.

The virus can spread rapidly in the herd, and up to 90% of the animals may show clinical signs and nearly all develop antibodies. However, the morbidity rate for VS varies considerably within species. 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.

The virus is transmitted by direct contact. Infected feed and water are primary means of disease spread. Small black gnats of Culicoides sp. can transmit this disease by feeding on an infected animal and subsequently feeding on a susceptible animal. Other biting flies like sand flies, black flies, and mosquitoes also transmit the disease when they bite susceptible animals. Movement of infected animals in commerce or pleasure can also spread the disease.

Humans can become infected with VS when handling affected animals if proper bio-safety methods are not followed. Prevalence of this disease in humans may be under reported because it may often go undetected or may be misdiagnosed. In humans, VS causes an acute influenza-like illness with symptoms such as fever, muscle aches, headache, malaise, and blisters in the mouth. The disease course is four to seven days.

There is no specific treatment or cure for VS. Mild antiseptic mouthwashes may bring comfort and more rapid recovery to an affected animal.

No vaccines are available in the United States. Owners can protect their animals from disease by avoiding congregation of animals in the vicinity where VS has occurred. Movement of animals, trucks, trailers, and other forms of contact should be restricted. Good sanitation and quarantine practices on affected farms usually contain the infection until it dies out. There is no approved vaccine for VS in the United States.

VS is very similar in its clinical appearance to Foot-and-Mouth Disease (FMD), so it is important to determine if, in fact, it is VS and not the more serious foreign animal disease, FMD. 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.

When a definite diagnosis is made on a farm, the following procedures are recommended:

Separate animals with lesions from healthy animals, preferably by stabling. Animals on pastures apparently are affected more frequently with this disease. As a precautionary measure, do not move animals from premises affected by vesicular stomatitis, unless they are going directly to slaughter -- for at least 30 days after the last lesion found has healed. Implement on-farm insect control programs that include the elimination or reduction of insect breeding areas and the use of insecticide sprays or insecticide-treated eartags on animals. Remember to use protective measures when handling affected animals to avoid human exposure to this disease.

For more information on vesicular stomatitis you may go to the USDA Animal Plant Health Inspection Service website: http://www.aphis.usda.gov/vs/nahss/equine/vsv/ or contact David S. Thain, DVM, State Extension Veterinarian at 775-784-1377 or Email dthain@cabnr.unr.edu

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