Vesicular stomatitis

Veterinary advice should be sought before applying any treatment or vaccine.

Vesicular Stomatitis

Vesicular stomatitis (VS) is a zoonotic disease, caused by the vesicular stomatitis virus (VSV), a member of the Rhabdoviridae family and Vesiculovirus genus. There are two distinct types of VSV that are recognized: New Jersey (NJ) and Indiana (IND). Within the IND, there are three associated subtypes that are classified as IND-1 (classical form), IND-2 (cocal virus), and IND-3 (alagoas virus). VSV mainly affects horses, cattle and pigs, however the virus can also infect sheep, goats, and rarely humans.

VS mainly affects horses living in the Western hemisphere and occurs frequently throughout South America, Central America, Mexico, and the Southwestern United States. In the United States, VS was first reported in 1916. Since then, outbreaks have occurred in horses and cattle living in New Jersey, New Mexico, Colorado, Utah, Texas, Arizona, Wyoming, Idaho, Montana and Nebraska.

Usually the first clinical sign observed in horses with VS is excessive salivation. Distinctive clinical signs associated with VS include the development of lesions along the upper surface of the tongue surface of the lips, corners of the mouth, gums, around the muzzle and nostrils. On rare occasions, horses may develop coronitis in the coronary band area, along with swelling and inflammation. Lesions are usually raised, blanched and occasionally fluid-filled vesicles. If vesicles occur, they are not apparent for very long, and will quickly rupture, leaving ulcerations and erosions. VS was named after the development of the classic associated signs of 'vesicular' and ulcerative lesions. Affected horses usually fully recover after a few days up to 2 weeks.

VSV is considered to be an arbovirus, as insect vectors are the primary mode of transmission. It is transmitted by numerous different species of insects, including sandflies, mosquitoes, deerflies, horseflies, biting midges, houseflies, eye gnats, black flies, and stable flies. There is also speculation that the VS virus is a plant virus found in pasture grasses. Being an arbovirus, outbreaks of VS usually occur during peak insect growth seasons, which starts in late spring or early summer and continues through to late fall.

Incubation Period
The incubation period for VSV varies from 1-3 days.


Oral lesions
Excessive salivation
Loss of appetite
Difficulty swallowing
Mild depression


  • History
  • Clinical signs
  • Physical exam
  • Laboratory tests


Report diseaseVS is a reportable disease, meaning that if you suspect that your horse has this disease, by law you need to report it to your veterinarian, or a state or federal veterinarian.
Sometimes no specific treatment is needed
Feeding soft feeds to reduce mouth discomfort
Anti-inflammatory medicine
Antibiotics may avoid secondary infection of abraded tissues.


  • Maintain recommended biosecurity practices.
  • Inactivated and attenuated virus vaccines have been experimentally tested, but are not yet available commercially


Good, horses usually make a full recovery.

Scientific Research References

Good Overviews

  • mouth ulcers icon

Risk Factors

  • Direct contact with infected animals
  • Exposure to high populations of biting insects.