Diagnosis

Serologic tests are available for detection of serum antibodies against VSV. A competitive enzyme-linked immunosorbent assay (cELISA) is used as a screening test. This test is rapid and detects both immunoglobulin M (IgM) and IgG. Serum neutralization (SN) and complement fixation (CF) tests are also used. Antibody can be detected within 5 to 8 days after infection. Both the cELISA and SN tests detect serum IgG, so antibody may be detectable in the serum for 1 to 3 years, making the interpretation of titers in a single serum sample difficult. A high CF titer in a single serum sample is more diagnostic of recent infection. A rising SN or CF titer is therefore required to definitively diagnose recent VSV infections. Virus isolation may be used to detect live virus in epithelial tags, swabs, or biopsy specimens from active lesions. Virus isolation is unrewarding after lesions have begun to resolve.

Treatment and Prevention

Clinical vesicular stomatitis is typically short lived and self-limited. In most cases, no specific treatment is indicated, and horses recover uneventfully in 1 to 2 weeks. Even in severe cases, only supportive care and prevention of secondary complications are required until lesions resolve. Secondary bacterial infections can be minimized by frequent cleansing of lesions with common mild antiseptics or application of topical antimicrobials. Cachexia can be avoided or remedied by providing palatable feeds, such as grain or complete feed pellets softened with water. Providing fluids or feed through a stomach tube would be necessary only in horses that are severely anorexic. Rarely, dehydration becomes severe enough to necessitate intravenous fluid support. Corrective shoeing might be required if hoof wall deformities developing secondary to coronary band lesions become sufficiently severe to interfere with normal function. Vesicular stomatitis is a zoonotic disease, and good biosecurity practices, such as wearing disposable protective gloves and frequent handwashing, are recommended.

Implementation of common management practices can reduce the risk for spread of this disease among and within premises. During regional outbreaks, all new arrivals to a facility or property should be considered suspect and should be quarantined for 3 to 5 days. No equipment, including feeders, waterers, salt blocks, brushes, and tack, should be shared among affected (or suspect) and nonaffected animals, and equipment and areas should be disinfected before noninfected animals are introduced. The viruses are easily inactivated with 1% formalin, 10% sodium hypochlorite, and other commonly used disinfectants. Vesicular stomatitis viruses are arthropod borne, so minimizing insect contact with livestock by stabling horses during periods of increased insect activity, using insect repellants on horses, controlling insects in areas where horses are housed, and moving animals away from pastures containing waterways during the summer months may help control disease spread. No vaccines are commercially available to prevent VSV infections in the United States.