At the writing of this article, one case of Vesicular Stomatitis Virus (VSV) has been diagnosed in Oklahoma. Oklahoma has not seen a case of VSV since the 1990s. Oklahoma joins Texas, New Mexico, Colorado and Wyoming with premises quarantined due to the virus. The current United States Department of Agriculture VSV situation report (July 29, 2019) states that 366 premises (174 confirmed and 192 suspected) are affected. Three hundred sixty-five of the premises have equine species affected and Colorado has one premise with affected cattle. The chances are more affected animals will be diagnosed in the future. The reason for this article is to alert the public about the disease and the restrictions placed on livestock from infected counties.
Vesicular stomatitis Virus is a viral disease that affects primarily horses and cattle. Pigs, sheep, goats, llamas, alpacas, and deer can also be infected, and on rare occasions humans can be infected. The disease normally occurs in the western and southwestern United States during the warmer months of the year and tends to be seen along waterways. Transmission occurs by direct contact with infected animals or by blood feeding insects.
Most animals do not die from this disease, but the economic losses can be significant in the lack of milk production and weight loss. The biggest concern with VSV is distinguishing it from foot and mouth disease and swine vesicular disease, both foreign animal disease with similar clinical signs. The only way to distinguish these diseases is through laboratory tests. Because of this concern, VSV is a reportable disease.
Production losses are not the only economic consequence of VSV. There are also economic losses due to restrictions since VSV is an internationally reportable disease in cattle, swine, sheep, goats, and deer. During an outbreak some countries may elect to restrict imports of animals or products from the United States. Also, states may impose regulations on interstate travel of livestock from infected states or counties where VSV has been diagnosed. Farms or ranches that are infected with VSV are quarantined for several days until after the last infected animal has healed. It may take several weeks for all the animals to recover from the disease. This sometimes results in lengthy quarantines.
The disease characteristics include fever at the onset. The most commonly recognized sign is excessive salivation or drooling. If the mouth is examined in early stages of the disease, it will reveal blister like lesions known as vesicles. Normally the vesicles are not seen because they have ruptured before the animal is checked. It is more likely to find ulcers or erosions of the inner surfaces of the lips, tongue, dental pad, and gums. Sometimes crusty lesions can also be seen on lips, nostrils, teats, prepuce, vulva, and coronary bands. Due to pain and discomfort, animals are reluctant to eat and drink. Animals may be lame due to the feet lesions. The disease normally resolves in 10 to 14 days.
An official diagnosis of the disease is based on laboratory testing. The disease cannot be determined on clinical signs alone.
The reason the disease sporadically occurs in some years and how it is transmitted is not known. Insects, animal movement, and mechanical transmission probably play a part in the spread of the disease. Once in the herd, the disease moves from animal to animal through contact with the saliva or ruptured vesicles of an infected animal.
There is no specific treatment for the disease. Infected animals are given supportive care such as soft food, rest, and water. Veterinarians will attempt to control pain and treat any secondary bacterial infections.
Since no vaccine is available, prevention begins with a good biosecurity plan. Producers should isolate any newly purchased animals for at least 30 days before introducing them to the herd. Any animals that appear ill should be separated from the herd and placed in quarantine. Also, producers should control insects.
Any producer that suspects his/her animals have VSV should have their animals examined by a veterinarian. If the veterinarian is suspicious, they will contact the state or federal animal health authorities.
Any livestock entering Oklahoma from a county infected with VS should go to http://www.oda.state.ok.us/ais/VesicularStomatitis.htm for the latest interstate requirements.
Producers who would like more information about VSV should contact their local veterinarian or local Oklahoma State University Extension Educator.
Additional information about VSV is available at https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/animal-disease-information/horse-disease-information/vs/vesicular-stomatitis.