Vesicular Stomatitis in Ruminants
Vesicular stomatitis is caused by Vesiculoviruses in the family Rhabdoviridae. Seen sporadically in North America during late summer and early fall. Vesicles occasionally form on the teats and in the interdigital space of cloven-footed animals; differentiation from Foot and Mouth Disease in must be made by regulatory veterinarians. Usually a mild disease but financial losses can be substantial especially in cows with teat lesions.
Vesicular stomatitis is a viral disease caused by 2 distinct serotypes of vesicular stomatitis virus—New Jersey and Indiana. Vesiculation, ulceration, and erosion of the oral and nasal mucosa and epithelial surface of the tongue, coronary bands, and teats are typically observed in clinical cases, along with crusting lesions of the muzzle, ventral abdomen, and sheath. Clinical disease has been observed in cattle, horses, and pigs and very rarely in sheep, goats, and llamas. Serologic evidence of exposure has been found in many species including cervids, nonhuman primates, rodents, birds, dogs, antelope, and bats. The viruses are zoonotic and may cause influenza-like disease in people working in close contact with the virus (eg, laboratory exposure, direct contact with lesions in infected animals).
The incubation period is 2-8 days and is typically followed by a fever. Ptyalism is often the first sign of disease. Vesicles in the oral cavity are rarely observed in naturally occurring cases due to rupture soon after formation; therefore, ulcers are the most common lesion observed during primary examination. Ulcers and erosions of the oral mucosa, sloughing of the epithelium of the tongue, and lesions at the mucocutaneous junctions of the lips are commonly seen in both cattle and horses. Ulcers and erosions on the teats are not uncommon in cattle and may result in secondary cases of mastitis in dairy cows. Coronitis with erosions at the coronary band are observed in cattle, horses, and pigs with subsequent development of lameness. Crusting lesions of the muzzle, ventral abdomen, sheath, and udder of horses are typical during outbreaks in the southwestern USA. Loss of appetite due to oral lesions and lameness due to foot lesions are normally of short duration, as the disease is generally self-limiting with complete resolution within 10-14 days. Virus neutralizing antibodies to either serotype persist, potentially for =5 yr, but reinfection can occur following a second exposure.
In most areas vesicular stomatitis is a reportable disease. Samples for diagnostic purposes are generally taken by regulatory veterinarians and are tested by government laboratories. Diagnosis is based on the presence of typical clinical signs and either antibody detection through serologic tests, viral detection through isolation, and/or detection of viral genetic material by molecular techniques. Samples for viral isolation may include vesicular fluid, epithelial tags from lesions, or swabs of lesions. Vesicular stomatitis viruses are easily propagated in cell culture. Three commonly used serologic tests are competitive ELISA, virus neutralization, and complement fixation. PCR may also be used to identify the virus. Of primary concern in diagnosis is differentiation of vesicular stomatitis from clinically indistinguishable but much more devastating viral diseases including foot-and-mouth disease, swine vesicular disease, and vesicular exanthema of swine. Horses are not susceptible to foot-and-mouth disease.