Vesicular stomatitis virus can cause blisters and sores in the mouth and on the tongue, muzzle, teats, or hooves of horses, cattle, swine, sheep, goats, llamas, and a number of other animals. | Photo: Courtesy Dr. Ashley Salinas

To help you protect your horses, we at TheHorse.com are sharing measures recommended by experts in a recent Journal of Equine Veterinary Science review article.

Insect Control

Because biting insects are the most common source of vesicular stomatitis virus (VSV), the best way to prevent VS is to remove insects from the horse and his habitat. The researchers specify four spatial scales you can use to reduce risk:

1. Neighborhood:

• Rotate pastures to avoid grazing during periods of water’s base flow just following peak runoff, which a hydrology study found correlated with past outbreaks.
• Move horses to higher-elevation pastures (4,000 feet and above) during high-vector seasons.
• Pesticides might be prohibited near drinking water sources; try propane-fueled insect traps that emit insect-attracting carbon dioxide, placed between insects’ breeding habitat and horses’ premises.

2. Premises:

• Provide a run-in shed that horses can use to escape insects.
• Remove manure regularly to reduce insect habitat.
• Provide good drainage (slope, well-drained sand, and porous gravel) around water sources to minimize habitat for water- and mud-loving insects.
• Keep vegetation short to minimize insects’ favored breeding and living areas.
• Manage irrigation to minimize pooled water and mud in fields.

3. Shelter:

• Keep animals indoors during insects’ active feeding periods (do some research to determine which insects are your area’s most common vectors and plan accordingly).
• Install mesh nets (0.1825 mm² pore size) or repellent-treated fabric on doors and windows or around stalls, or use as an outdoor net-shed.
• Install downward-blowing fans to keep insects off horses.
• Minimize bright insect-attracting lights at night, including light traps and bug zappers.

4. Animal:

• Apply topical repellents and insecticides with the understanding that they aren’t equally effective on all insect species.
• Use protective horsewear such as fly sheets, leg wraps, fly masks, and ear nets, especially those treated with synthetic pyrethroids such as pyrethrin, permethrin, and deltamethrin. But note that these substances only protect the areas directly under the treated fabric.
• Reduce exposure to the parts of the horse’s body that biting insects favor most: belly, legs, flanks, hindquarters, ears, and abrasion sites.

Take-Home Message

The study authors concluded that owners must do their research to learn which insects in their area are threats and tailor prevention approaches accordingly. With due diligence and careful management, you can significantly reduce the risk of your horse contracting VS