Vesicular Stomatitis (VS) is a viral disease named for vesicular lesions that appear on the face, lips, tongue, ears, and coronary band. Vesicular stomatitis is a reportable disease in the United States, meaning any suspected cases must be reported to state/federal animal health officials.

Incubation: The incubation period is the time from exposure to the virus to when a horse shows clinical signs of infection. The incubation period for VS is two to eight days.

Transmission: Transmission occurs through black flies, sand flies, and biting midges. VS can also be spread by direct contact between horses and through indirect contact with infected surfaces.

Clinical Signs: Signs include blisters and scabs on the lips, muzzle, nose, tongue, and coronary band as well as crusting, excessive salivation, lameness, and difficulty chewing.

Diagnostic Testing: Diagnosis is determined by the presence of vesicular lesions and detection of virus. Samples from lesions are tested to confirm infection. Once confirmed, animal health officials may require quarantine and restrict movement to prevent the further spread of the virus.

Treatment: There is no specific treatment, however pain relievers and anti-inflammatories can be used to help alleviate pain.

Prognosis: VS is rarely fatal. Most lesions will resolve within 14 days. Horses with lesions in their mouth may be reluctant to eat and drink which can lead to complications.

Prevention: Practicing good biosecurity can be used to prevent VS. To help reduce further spread once VS has been confirmed on a premises, isolation of all sick horses is required until all horses have recovered and there are no additional active lesions present. Fly control is essential to preventing spread of the virus.