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BROOMFIELD, Colo. — Two horses in Weld County tested positive July 3 for vesicular stomatitis.

Two other states, New Mexico and Texas, reported confirmed cases this year, according to a news release from the Colorado Department of Agriculture.

The horses, which live in two different parts of Weld County, have been placed under quarantine.

Vesicular stomatitis primarily affects horses and cattle, and occasionally swine, sheep, goats, llamas, and alpacas, according to the release. The transmission process is not completely understood, but black flies, sand flies, and biting midges could be carriers.

Signs include  vesicles, erosions, and sloughing of the skin on the muzzle, tongue, teats, and coronary bands. According to the release, excessive salivation is often the first sign of disease, along with a reluctance to eat or drink. Lameness and weight loss may follow.

Although humans can become infected when handling the affected animals, it rarely occurs.  To avoid human exposure, people should use personal protective measures when handling affected animals.

Colorado State Veterinarian Keith Roehr completed the initial investigation into the cases.

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

Insects were likely carrying the disease, and mitigation efforts are underway to reduce the chance the virus will spread, according to the release. The horses will be under quarantine until at least 14 days after the onset of lesions.

No United States Department of Agriculture-approved vaccines exist for vesicular stomatitis.

The Weld County epidemiological investigation indicates an incursion of VSV-infected insect vectors is the likely source of infection. Biosecurity measures and vector mitigation have been instituted on both locations to reduce the potential spread of the virus. The animals are being monitored daily and the index premises will remain under state quarantine until at least 14 days from the onset of lesions in the last affected animal on the premises. There are no USDA approved vaccines for VSV.

The following are tips for livestock owners from the Colorado Department of Agriculture:

  • 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. Contact information for all state veterinarian offices is listed here.
  • 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 be beneficial in reducing risks. Be sure to stay informed of any new livestock event requirements. See the Vesicular Stomatitis Guidelines for Shows and Fairs.
    Important Points for Veterinarians

Report any vesicular disease to the State Veterinarian’s Office in Colorado at 303-869-9130. If after hours, the voice message will indicate which staff veterinarian on call.