Vesicular stomatitis

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

Vesicular Stomatitis

Vesicular Stomatitis (VS) is a viral disease of horses, cattle, and other livestock living in the Western hemisphere--with outbreaks reported in South America, Central America, Mexico, and the Southwestern United States. The disease is characterized by the appearance of short-lived vesicles which turn into ulcers and erosions inside and outside the horse's mouth, tongue, nasal mucosae, and occasionally the coronary bands. It is caused by infection with either of two serotypes of the vesicular stomatitis virus (VSV)---the VSV New Jersey (VS-NJ) or VSV Indiana (VSV-IND). Approximately 30% of infected animals on a property with an outbreak develop clinical signs of disease.

Clinical Signs of Vesicular Stomatitis

Approximately 70% of affected animals will show no overt signs of disease. Those who do develop signs, usually will develop blanched areas after 1-3 days of exposure, which turn into vesicles--which appear as lesions on the tongue, lips, corners of the mouth, gums, and around the muzzle and nostrils. On rare occasions, horses may develop coronitis in the coronary band area, along with swelling and inflammation. Others may develop lesions on mammary glands and external genitalia. Lesions are usually raised, blanched and occasionally fluid-filled vesicles. Vesicles will quickly rupture, leaving ulcerations and erosions which usually heal within 7 to 14 days.

How Vesicular Stomatitis is Transmitted

VSV is primarily spread by insects---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.


Vesicular lesions inside mouth, tongue, lips, and nasal mucosa
Lesions on mammary glands, external genitalia and coronary bands
Excessive salivation
Loss of appetite
Difficulty swallowing
Mild depression


  • History
  • Clinical signs
  • Physical exam
  • Serologic tests: A variety are available for antibody detection.
  • Molecular techniques: For detection of viral genetic material.
  • Virus isolation: Used to detect live virus in epithelial tags, swabs, or biopsy specimens from active lesions.



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, and horses unevenfully recover in 1 to 2 weeks.
Feeding soft feeds to reduce mouth discomfort
Supportive care
Anti-inflammatory medicine
Prevent secondary infectionsFrequently cleanse lesions with common mild antiseptics or topical antimicrobials.


  • 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

General Overviews

Risk Factors

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