Vesicular stomatitis, or VSV, is a virus endemic to the warmer regions of North, Central, and South America. Texans with livestock and horses are likely familiar with the disease, as outbreaks of VSV typically occur in the state every few years.
The current national outbreak of VSV began on April 13, when the National Veterinary Services Laboratory reported VSV-positive premises in New Mexico. On April 23, the first in-state VSV finding of this outbreak was reported at an equine facility in Starr County, Texas.
Dr. Leslie Easterwood, a clinical assistant professor at the Texas A&M College of Veterinary Medicine & Biomedical Sciences, informs horse and livestock owners on what they should know about this virus and how they can keep their animals safe and healthy.
“Vesicular stomatitis is a viral disease that affects horses, donkeys, mules, cattle, and swine,” Easterwood said. “This virus is spread by insect vectors, including blackflies, sand flies, and members of the Culicoides species (usually ‘no-see-um gnats’).”
The current serotype, or “version” of VSV, causing this outbreak is known as the New Jersey serotype, which Easterwood characterizes as being very virulent and contagious.
The virus causes crusting, ulcerative, and vesicular (fluid-filled) lesions of the lips, tongue, coronary bands (where the hairline meets hoof), mammary glands, muzzle, and nostrils.
“These lesions are very inflamed, causing swelling, pain, and excess salivation,” she said. “Many affected animals are lame due to the inflammation of the coronary bands, and have a hard time chewing and swallowing their feed due to the lesions on their lips and tongue.”
Easterwood says that VSV is self-limiting, meaning the disease tends to go away on its own, but that anti-inflammatory medications may help to decrease pain and swelling caused by the lesions.
To protect animals from contracting VSV, Easterwood recommends practicing good fly control and limiting exposure to infected animals, as the virus can be spread directly from animal to animal or between shared spaces and equipment, such as water buckets.
In addition to causing harm to individual animals, VSV can also be more broadly dangerous to agricultural industries.
“This virus can be especially detrimental to our milk producing cows,” Easterwood said. “They can become lame and the lesions decrease their milk production.
“With horses, infected individuals are not allowed to travel to events where they could be comingled and transmit the virus. VSV could have economic impacts on our show horses, racehorses, commercial dairy cattle, and commercial swine operations.”
If an owner suspects that one of their animals is suffering from VSV or has been exposed to an infected animal, they should consult their veterinarian promptly due to the highly contagious nature of the condition.
“This viral disease is a reportable disease, which means that the Texas Animal Health Commission (TAHC) will be informed when an animal tests positive,” Easterwood said. “TAHC will then control how the animal’s movements are restricted until the symptoms resolve and the outbreak is over.”