RBC I Vesicular Stomatitis (VS) is a contagious disease that afflicts horses, livestock, wildlife and even humans has found its way into northwestern Colorado and Rio Blanco County. The disease is caused by a virus which although rarely life threatening, can have significant financial impact on the horse industry.
Clinical Signs & Diagnosis
When vesicular stomatitis occurs in horses, blister-like lesions develop on the tongue, mouth lining, nose and lips. In some cases, lesions also develop on the coronary bands, or on the udder or sheath. When VS is suspected, an exact diagnosis should be obtained by testing the blood for virus-specific antibodies. Testing is necessary to rule out the possibility that the lesions are caused by photosensitivity (sunburn), irritating feeds or weeds, or toxicity from non-steroidal anti-inflammatory medications like phenylbutazone.
If you horses have any of these symptoms it is suggested you contact your veterinarian for assistance, says Bill Ekstrom CSU Extension Agent.
The incubation period for vesicular stomatitis—meaning the time from exposure until the first signs appear—ranges from two to eight days. The disease generally runs its course within two weeks, although it may take as long as two months for the sores to entirely heal. Until the ulcers are completely healed, the horse remains infective and the potential remains for disease to spread.
While a horse is suffering from vesicular stomatitis, feeding soft feeds may reduce mouth discomfort. Anti-inflammatory medications as supportive care help to minimize swelling and pain so a horse will continue to eat and drink. Secondary bacterial infection of ulcerated areas is another concern. If fever, swelling, inflammation or pus develops around the sores, treatment with antibiotics may be required. However, there is little an owner or veterinarian can do but wait for healing to occur and take appropriate precautions to minimize the risk of spread of the disease to other horses and livestock.
There are still many questions regarding how vesicular stomatitis is transmitted. Due to the seasonal occurrence of VS during summer through early fall, it is believed that insects such as biting flies and gnats transmit the virus. Stable and houseflies are other possible but unlikely vectors. VS also seems to be passed from horse to horse by contact with saliva or fluid from ruptured blisters. Physical contact between animals, or contact with buckets, equipment, housing, trailers, feed, bedding or other items used by an infected horse can provide a ready means of spread.
By observing the following guidelines you can help prevent the occurrence of VS:
• Healthy horses are more disease resistant so provide good nutrition, regular exercise, deworming and routine vaccinations.
• Isolate new horses for at least 21 days before introducing them into the herd or stable.
• Observe your horse closely. Immediately isolate any horse that shows signs of infection.
• Implement an effective insect control program. Keep stabling areas clean and dry. Remove waste and eliminate potential breeding grounds (standing water, muddy areas) for insect vectors.
• Use individual rather than communal feeders and equipment.
• Clean and disinfect feed bunks, waterers, horse trailers and other equipment regularly.
• Be sure that your farrier and other equine professionals who come into direct contact with your animals exercise due care so as not to spread the disease from one horse or facility to the next.
• On farms where VS has been confirmed, handle healthy animals first, ill animals last. Handlers should then shower, change clothing and disinfect equipment to prevent exposing others.
• Anyone handling infected horses should implement proper biosafety methods, including wearing latex gloves.
For more information contact your local CSU Extension office or your veterinarian.