The Vesicular Stomatitis (VS) outbreak continues to expand in Wyoming. Cases have been reported in horses on 6 different premises in Goshen County to date. Eight premises in Platte County have recently been quarantined. Cases in Platte County involve both horses and cattle.

Beautiful horses
Public domain image/Dusan Bicanski

The main symptoms of VSV are slobbering, blisters, sores and sloughing of skin in the mouth, on the tongue, on the muzzle, inside the ears and on the coronary band above the hooves. Lameness and weight loss may also occur. VSV-infected horses and/or cattle have been found already in 2015 in Colorado, New Mexico, South Dakota, Texas, Utah, and Arizona. VSV can threaten other livestock species, including sheep, goats and pigs.

Flies and midges are the main vectors for VSV. The virus is also spread through direct contact with infected livestock and indirectly through contact with contaminated equipment and tack. Fly control is the most important step in preventing the disease. Good sanitation and bio-security measures can help avoid exposure.

Wyoming’s most recent previous outbreaks of VSV were in 2005 and 2006. Nearly all of the affected equine during those years were pastured along drainages or had very recent history of exposure to low-lying, riparian areas. We advise livestock owners, if possible, to move their healthy animals to higher, dryer ground until the VSV insect vector season subsides. That is generally after two hard frosts.

VSV is particularly significant because it is clinically indistinguishable from foot-and-mouth disease (FMD), swine vesicular disease, and vesicular exanthema of swine, all serious foreign animal diseases (FAD). Because of similarities to these FADs, it is essential to quickly confirm a diagnosis with laboratory testing. Of the vesicular diseases, VSV is the only one that affects horses, and the presence of lesions is suggestive of VS.