Vesicular Stomatitis: What You Need to Know

According to the U.S. Dept. of Agriculture (USDA), as of August 23, 2019, seven states have reported premises that are confirmed positive for vesicular stomatitis (VS). To be confirmed positive, a premises may have one or multiple horses with the disease. Affected states include Colorado, Nebraska, New Mexico, Oklahoma, Texas, Utah, and Wyoming.

So what is VS and should you, as a horse owner, be concerned?

While VS is highly contagious, it is not usually life-threatening. Excessive salivation is often the first clinical sign to be noticed. It can take anywhere from two to eight days for clinical signs to show up once a horse has been exposed to the virus.
Clinical signs of VS include:

• Drooling/frothing at mouth
• Fever
• Lesions that resemble blisters in/around the mouth, lips, tongue, nose, coronary band and/or sheath/udder
• Reluctance to eat
• Lameness (if lesions form around coronary band)
Contact your veterinarian right away if you notice any clinical signs of VS. To positively confirm presence of the virus, the veterinarian can draw blood for testing or take swabs from the lesions.

An infected horse may require anti-inflammatory medication to encourage eating and drinking. VS usually runs its course in about two weeks, but it can take longer for lesions to heal. Infected horses should be separated from other horses on the property to avoid spreading the disease.

Although VS also infects cattle, the majority of U.S. cases this summer have been found in horses.

Because VS is a "reportable" disease, the veterinarian treating a horse suspected of having VS must report it to state and federal animal health authorities. The premise will then be quarantined for at least 14 days from the onset of the last case on that property. This is done to reduce risk of the disease spreading.

Black flies, sand flies and midges are considered known vectors of VS, but other insects may also transmit it, so a diligent fly/insect control program is important to reduce the risk of transmission. Apply fly repellent as often as needed, including your horse's face and ears. Using a fly mask can also help protect horses.

Good horse-keeping practices (regular manure removal, no standing water, etc.) are important to eliminate insect breeding areas.

The virus can also be spread directly from horse to horse and by indirect contact when objects (feed and water buckets, grooming equipment, tack, horse trailers, bedding, hitching/tie posts, etc.) are contaminated by an infected animal. Don't share equipment at shows or at your boarding barn. You'll want to routinely disinfect trailers, waterers, feed bunks and equipment.

People can unintentionally spread the virus by their shoes, clothing and hands after touching an infected animal. This is a good reason to make "hands off" a habit at shows and other horse events. Don't pet other horses and limit handling of your horse by others. Don't let your horse use communal water sources or eat where other horses have been. Wash your hands frequently and keep hand sanitizer available.

Humans can contract the disease and although they don't tend to develop the mouth blisters, VS in humans can cause severe flu-like symptoms.

The good news is that healthy horses are more resistant to VS and other diseases, so do everything you can to keep your horse in optimal health. This includes balanced nutrition, a good exercise program, routine veterinary and dental exams, regular hoof care, deworming and staying current on vaccinations, based on your individual horse's needs.