Vesicular stomatitis diagnosed in Colorado; travel requirements remain in effect

Source: Colorado Department of Agriculture

A Las Animas County, Colo., premises is under quarantine after a horse tested positive for vesicular stomatitis (VS). The horse had not recently traveled and is believed to have been infected by insects.

“While this is the first case diagnosed in Colorado in 2012, there have been several cases identified in the Rio Grande River valley of New Mexico,” said State Veterinarian, Dr. Keith Roehr. “This Colorado case represents a northern movement of the virus that has been typical in past years.”

VS is a foreign animal disease that occurs sporadically in certain areas of the western U.S. The last confirmed case of VS in Colorado was diagnosed in 2006.

Travel Requirement

The Colorado Department of Agriculture’s State Veterinarian’s Office has issued a travel requirement for horses, mules, cattle, bison, sheep, goats, swin, and camelids entering the state from states with confirmed cases of VS.

This requirement states that health certificates should include the following statement from the issuing veterinarian, “I have examined the animal(s) represented on this Certificate of Veterinary Inspection (CVI) and have found no signs of vesicular stomatitis and they have not originated from a premises under quarantine for vesicular stomatitis.”

“The purpose of this requirement is to ensure that veterinarians issuing health certificates are aware of the spread of Vesicular Stomatitis and are vigilant in looking for signs of the virus.  VS can be painful for the animals and costly to their owners,” said Roehr. “While this virus does not typically cause death, the animal can suffer from painful sores so it is important to monitor herds for symptoms.”

Important Points for Veterinarians

  • Any vesicular disease of livestock is reportable to the State Veterinarian’s Office in Colorado – to report call 303-239-4161. 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.

The Colorado Department of Agriculture recommends the following tips and guidelines for the horse and livestock owners:

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 livestock owners should contact the state of destination when moving livestock interstate to ensure that all entry requirements are met. A list of contact information for all state veterinarians’ offices is available at:
  • Colorado fairs, livestock exhibitions, and rodeos may institute new entry requirements based on the extent and severity of the current VS outbreak. Be sure to stay informed of any new changes concerning event requirements.

Vesicular Stomatitis Guidelines for Shows and Fairs

The Colorado state veterinarian’s office is recommending that livestock events exercise extra precaution measures to minimize the transmission of Vesicular Stomatitis. The following strategies should be implemented:

  1. Participants, regardless of origin should, when possible, arrive at the event with a Certificate of Veterinary Inspection that was issued within 48 hours of departure for the event.
  2. The Certificate of Veterinary Inspection should contain a statement from the issuing veterinarian that states: “I have examined the animal(s) represented on this Certificate of Veterinary Inspection (CVI) and have found no signs of vesicular stomatitis and they have not originated from a premises under quarantine for vesicular stomatitis.”
  3. Out-of-state participants should check with their state’s animal health officials to determine the requirements for their livestock’s return to that state.
  4. All livestock that arrive at an event without a Certificate of Veterinary Inspection issued within 48 hours of arrival should receive an oral examination for VS lesions upon arrival at the event.
    1. A qualified, licensed and accredited veterinarian should be available to oversee the inspection process.
    2. Any livestock that exhibit clinical signs of VS shall be immediately removed from the event and reported to a Colorado animal health official 303-239-4161.
    3. Colorado livestock will be returned to their premises and quarantined.
    4. Out-of-state livestock should be taken to a predetermined isolation facility where they would be held until an appropriate quarantine site can be identified.
    5. During the event common water and feed sources should be minimized and insect repellent applied daily, with particular attention to the animals ears.

Vesicular Stomatitis Transmission

Most cases are spread by insect vectors, particularly along river valleys. Biting flies are known to be capable of transmitting VS. Sand flies (Lutzomyia spp.) and black flies (Simulium spp.) have been identified as important insects in the transmission of VS.

Vesicular Stomatitis Signs

VS susceptible species include horses, cattle, sheep, pigs, deer and other species of animals. 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. Click here to see pictures of animals infected with VS.

As the disease progresses, the ruptured vesicles erode to produce areas where dead tissue becomes separated from the surrounding wound near the mouth or hoof. Animals with oral lesions may refuse to eat or drink due to discomfort which results in weight loss. Coronary band lesions can result in lameness in one or more feet. In severe situations, the hoof may slough or hoof growth may be permanently impacted.

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.

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 diagnosed with VS are isolated until they are free from clinical signs of disease and no longer present a risk to other livestock. There are no US Department of Agriculture approved-vaccines for VS.

For additional information, contact the Colorado State Veterinarian’s office at 303-239-4161 or visit

To view the current location of cases and other important updates and information, Click here to download a fact sheet about VS from the USDA.