Search Menu
Menu »
Home » Vesicular Stomatitis

Vesicular Stomatitis

Vesicular Stomatitis (VS) is a viral disease that usually affects equines and cattle, but can also affect sheep, goats, pigs, llamas, alpacas, and camels. This disease is common in South and Central America, but occasional outbreaks are seen in North America. In May 2023, an outbreak of the New Jersey strain of VS began in California.  Cases have also been diagnosed in Texas and Nevada.

Learn more here:

Signs of VS appear 2-8 days after infection and include:

  • Blisters, sores, or scabbing on hairless areas such as the mouth, nose, ears, hooves, sheath, and udder
  • Fever
  • Drooling/frothing at mouth
  • Reluctance to eat
  • Lameness if lesions develop around the hoof

VS does not usually cause animals to die. There is no specific treatment or cure for VS, but anti-inflammatory medications and fluids may help make infected animals more comfortable as they recover. 

Animals are tested for VS by drawing blood and swabbing the sores or scabs.  The blood samples test for antibodies to the disease, and the swabs are used to detect the virus.  In cattle, sheep, goats, and pigs, the disease can look just like Foot and Mouth Disease, so additional samples like oral fluid are taken to rule this out. Samples are sent to either the Utah Veterinary Diagnostic Laboratory or USDA’s National Veterinary Services Laboratory.  

Once a case of VS is diagnosed in a county, other affected horses do not have to be tested.  However, they do need to be reported and quarantined.  All cattle, sheep, goats, and pigs with signs of disease must be tested for VS regardless of whether the county is already affected.

VS is spread by biting flies and midges and by contact between infected animals. Infected animals shed the virus from their blisters, so contact with infected animals or shared water, feed, buckets, and other equipment, as well as shoes, clothing, and hands can spread VS. Sunlight, heat, and many common disinfectants will destroy the VS virus.

To reduce the risk of spread of VS to animals on your property:

  • Isolate new animals or animals that have been to a show or event for 14 days
  • Keep animals healthy with good nutrition, regular exercise, vaccinations, and deworming
  • Practice insect control (see below)
  • Avoid shared feeders, waterers, and other equipment at shows and events.

Once the disease is diagnosed on a property, spread between animals can be avoided by:

  • Separating sick animals from healthy animals
  • Handling healthy animals before sick animals
  • Washing hands and boots and changing clothes after handling sick animals
  • Not moving animals until the quarantine is complete
  • Insect control

The key to a successful fly control program is to eliminate breeding sites.  Clean barns and corrals once a week to break fly life cycles.  Check for wet areas around the barns where flies may lay eggs.  

Insecticides can temporarily reduce fly and midge populations by killing adult flies.  Residual sprays should be applied to walls, ceilings, and rafters. Foggers and sprays can provide a quick knock-down.  Fly baits work on house flies, but not stable flies, and should be kept out of reach of animals.

Other methods of insect control include:

  • Screening of feed and tack rooms and box stalls
  • Fans that blow downward and outward near doors
  • Fly traps and sticky paper to monitor fly numbers
  • Fly parasites

Human cases of VS are rare, but can happen. VS causes flu-like symptoms in people who come in contact with blisters or saliva, so wear gloves when handling infected horses and wash your hands thoroughly before eating or rubbing your eyes.  Signs of VS in people include fever, muscle aches, headaches, and tiredness.

Many states require that health certificates for susceptible animals in an affected state or county be issued within a specific number of days before movement.  More information on specific state requirements can be found at:

Horses from positive states cannot travel on an extended electronic certificate of veterinary inspection (EECVI), also known as an equine passport.  A health certificate is required for each movement.