Vesicular Stomatitis

By Sandy Gagnon, MSU Extension Equine Specialist. Excerpts taken from Montana Department of Livestock Web site and USDA APHIS web site.


"Because vesicular stomatitis (VS) is often clinically indistinguishable from FMD, confirming a diagnosis with laboratory tests is critical."


Vesicular stomatitis (VS) is a viral disease characterized by fever, vesicles, and subsequent blisters. The vesicles form on the mouth, tongue, lips, feet, teats, and mammary glands of affective animals. These vesicles or blisters tend to be large and very painful.

VS affects a wide range of hosts. It primarily affects cattle, horses, and swine. This disease occasionally affects sheep and goats. Many species of wild animals, including deer, bobcats, goats, raccoons, and monkeys, have been affected. Humans can also become infected with vesicular stomatitis when handling affected animals.

Prevalence in Montana

Vesicular stomatitis has been identified in Montana. As of September 11, 2005 - Montana has 35 positive premises under quarantine. The following APHIS web sites provide, up-to-date information concerning the prevalence rates in Montana and other states:

Pathology and Symptoms

The symptoms are similar to foot and mouth disease; therefore, it is extremely important to seek proper vet diagnosis. Vesicular stomatitis is a reportable disease (see Montana Department of Livestock for further requirements).

Vesicular Stomatitis (VS) has an incubation period from 2 to 8 days. The incubation period in humans is 24 to 48 hours.

The vesicles that occur in the mouth and around the lips are very painful. They cause excess salivation or slobbering and the animals do not want to eat or drink and therefore, lose weight. Walking is also difficult, as lesions form around the coronary bands of the feet and cause lameness and/or a reluctance to walking. Lesions on mammary glands can cause severe mastitis and reluctance to allow nursing. Dairy cows have a severe drop in milk production. Infected humans experience flu-like symptoms (fever, headache, muscle aches) with an occasional blister around the nose or mouth. The disease course in humans is usually 4 to 7 days.


Because vesicular stomatitis (VS) is often clinically indistinguishable from FMD, confirming a diagnosis with laboratory tests is critical. An animal has VS if it demonstrates clinical signs that are consistent with the disease and has a positive viral isolation and/or has one or more positive serologic tests.


Most animals affected with VS recover in 2-3 weeks; however if the vesicles become infected by bacteria or fungi, recovery can take longer. Debilitated animals may be aided by broad spectrum antibiotic therapy to control secondary bacterial invaders. Most animals recover from the disease.

There is no specific treatment or cure for vesicular stomatitis. Treatment of affected animals may involve treating the symptoms. :

  • Mild antiseptic mouthwashes may bring comfort and more rapid recovery to an affected animal.
  • High-energy liquid gruel feed or electrolytes added to the water supply can be helpful for animals having difficulty eating or drinking.
  • Oral ulcers can be swabbed with a 1% to 2% solution of Lugol's iodine.
  • Foot ulcers can be sprayed twice daily with a saturated solution of copper sulfate.
  • Teat ulcers can be treated with spray solutions of antibiotics and anti-inflammatory drugs.
  • Death loss can be avoided if ill cattle or horses are offered shade, fresh water, and soft feed (although keep infected animals separate from non-infected animals).

Vaccines for the prevention of VS are not currently licensed for use in the United States due to sporadic nature of the disease and the fact that most all affected animals recover.

Transmission and Prevention

The method of transmission is not fully understood. It is believed that the virus is spread through insect vectors (sand fly - Lutzomyia shannoni, and the black fly- Simuliidae), movement of infected animals, and contaminated objects. Once introduced into a herd, the disease apparently moves from animal to animal by contact or exposure to saliva or fluid from ruptured lesions.

Owners can protect their animals from this disease by avoiding congregation of animals in the vicinity where vesicular stomatitis has occurred. Good sanitation and quarantine practices on affected farms usually contain the infection until it dies out.

When a definite diagnosis is made on a farm, the following procedures are recommended:

  • Separate infected and healthy animals: Separate animals with lesions from healthy animals, preferably by stabling. Animals on pastures apparently are affected more frequently with this disease.
  • Control movement of animals: As a precautionary measure, do not move animals from premises affected by vesicular stomatitis - unless they are going directly to slaughter - for at least 30 days after the last lesion found has healed.
  • Insect control: Implement on-farm insect control programs that include the elimination or reduction of insect breeding areas and the use of insecticide sprays or insecticide-treated ear tags on animals.
  • Use protective measures when handling affected animals to avoid human exposure to this disease.
  • Disinfect milking machines between cows.
  • Milk infected cows last.
  • Commercial vaccines are available, but efficacy has not been field tested.

Effective disinfectants are:

  • 2% sodium carbonate
  • 4% sodium hydroxide
  • 2% iodophore disinfectants
  • Chlorine dioxide disinfectants
  • Ether and other organic solvents
  • 1% formalin

For more information, contact your veterinarian or the Montana Department of Livestock.

Frequently Asked Questions

Horse Shows

  • If a horse at a show, sale or rodeo exhibits signs suggestive of VS, it should be immediately isolated and examined by a vet, state vet, USDA-APHIS.
  • After inspection, if it appears to have VS, that animal as well as all others on premise will be quarantined
  • Samples will be collected
  • Length of quarantine, animals and premise to be quarantined will be determined case by case

Common Quarantine Lengths

  • 42-45 days if animal/premise is VS positive
  • 7-10 days if all test results are negative for all animals tested
  • Federal or State vet concurs that, based on lesions, it was most likely not VS

Are horses contagious during incubation period?

  • When virus enters animal, multiplies within skin cells.
  • VSV not detected in blood of naturally infected animals.
  • Lesions appear in 1-3 days and one region of the body.
  • New lesions do not appear more than 3-4 days after the first ones are formed.
  • Resolution of lesions most commonly occurs within 10-14 days
    VSV is found in high concentrations within lesions, and is shed from these active lesions, but does not appear to be shed in urine, feces or milk.
  • Animals are HIGHLY CONTAGIOUS for the first 48-72 hours when clinical lesions are seen, however, shedding may continue as lesions begin to heal.
  • Early indicators of VS include lethargy, swollen lips/muzzle, drooling, fever, lameness.

If horses do not share feed/water buckets, kept from physical contact, and good fly spray used, what is likelihood they can still contract the disease?

  • Much less likely to contract if you adhere to above biosecurity principles
  • Also, ask people who are in physical contact with multiple animals to wash hands with antiseptic soap between contact with different animals
  • Any shared equipment should be cleaned/disinfected between animals (Nolvasan or Clorox diluted in water

What recommendations do you have for horse shows?

  • All horses need a Certificate of Veterinary Inspection issued within 24 hours prior to arrival at show
  • Local vet must re-check horses at arrival as well as during show