Vesicular Stomatitis Cases Confirmed in 11 Colorado Counties

Broomfield, Colo. – The Colorado Department of Agriculture has confirmed cases of vesicular stomatitis (VSV) in Adams, Archuleta, Boulder, Broomfield, Delta, La Plata, Larimer, Mesa, Montezuma, Morgan and Weld counties in Colorado. All confirmed cases in Colorado have been in horses with the exception of one bovine case as indicated with asterisk on the table below.  

“We understand that the VSV outbreak and quarantines are impacting the ability for people to bring their horses and livestock to fairs and shows,” said Dr. Keith Roehr, Colorado State Veterinarian. “The quarantines and hold orders must be followed, however, for the health and protection of all equine and livestock in Colorado.” The total count of premises under quarantine for VSV by county is outlined in the table below.  CDA’s Animal Health division is updating this table regularly with the latest data on its CDA VSV website.

Please see the USDA APHIS Veterinary Services website to read the current situation report for all confirmed cases in the U.S. 

The first case of VSV in Colorado was reported on July 3rd in Weld County by a field veterinarian from the State Veterinarian’s Office at the Colorado Department of Agriculture.  An incursion of VSV-infected insect vectors is the likely source of infection. There are no USDA approved vaccines for VSV.

Vesicular Stomatitis Background

Vesicular stomatitis is a viral disease that primarily affects horses and cattle, and occasionally swine, sheep, goats, llamas, and alpacas. The transmission process of VSV is not completely understood, but includes insect vectors such as black flies, sand flies, and biting midges.

The incubation period ranges from 2-8 days. Clinical signs include vesicles, erosions, and sloughing of the skin on the muzzle, tongue, ears, teats, and coronary bands. Often excessive salivation is the first sign of disease, along with a reluctance to eat or drink. Lameness and weight loss may follow.

Humans may become infected when handling affected animals, but this is a rare event.  To avoid human exposure, individuals should use personal protective measures when handling affected animals.


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. 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 (CVIs or health certificates) 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 and Horse Owners

Any vesicular disease of livestock is reportable to the State Veterinarian’s Office in Colorado – to report call 303-869-9130. If after hours, the voice message will indicate which staff veterinarian on call.

Additional resources