Positive diagnosis of Vesicular Stomatitis in horses in Weld County

Colorado has become the second state in the country to have a confirmed case of vesicular stomatitis (VS). Four horses on two Weld County premises tested positive for the disease and have been placed under quarantine. The horses involved in these index cases have no history of travel.

On July 17, the National Veterinary Services Laboratory reported a positive test on samples submitted from four horses in Weld County. The initial Colorado disease investigation was performed by one of the field veterinarians from the State Veterinarian’s Office at the Colorado Department of Agriculture. Previous positive cases of vesicular stomatitis in 2014 have been diagnosed in the southern area of Texas near the Mexico border and more recently in Bastrop and Travis Counties just south of Austin, Texas.

“Vesicular stomatitis can be painful for animals and costly to their owners,” said State Veterinarian, Dr. Keith Roehr. “The virus typically causes oral blisters and sores that can be painful causing difficulty in eating and drinking.”

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 clinical signs of VS are isolated until they are healed and determined to be of no further threat for disease spread. 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 susceptible species include horses, mules, cattle, bison, sheep, goats, pigs and camelids. The clinical signs of the disease include vesicles, 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. The transmission of vesicular stomatitis is not completely understood but components include insect vectors, mechanical transmission, and livestock movement.

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.
Colorado veterinarians and livestock owners should contact the state of destination when moving livestock interstate to ensure that all import requirements are met. A list of contact information for all state veterinarians’ offices is available at www.colorado.gov/ag/animals and click on “Import Requirements.”

Colorado fairs, livestock exhibitions, and rodeos may institute new entry requirements based on the extent and severity of the current VS outbreak. Certificates of Veterinary Inspection issued within 2-5 days prior to an event can beneficial to reduce risks. Be sure to stay informed of any new livestock event requirements.

During an event, important VS disease prevention procedures include minimizing the sharing of water and feed/equipment, applying insect repellent daily (especially to the animals ears), and closely observing animals for signs of VS.

If moving livestock internationally please contact the USDA APHIS VS Colorado office at 303-231-5385 to determine if there are any movement restrictions or testing requirements for VSV.

Important points for veterinarians:

Any vesicular disease of livestock is reportable to the State Veterinarian’s Office in Colorado – to report call 303-869-9130. If after-hours, call the same number to obtain the phone number of the staff veterinarian on call.

Since VS is considered a foreign animal disease, any case with clinical signs consistent with VS will warrant an investigation by a state or federal foreign animal disease diagnostician (FADD).

When VS is suspected, the FADD will gather the epidemiological information, take the necessary blood samples, collect the necessary fluid or tissue from the lesions, and inform the owners and the referring veterinarian as to necessary bio-security and movement restrictions.