Vesicular stomatitis (VS) has been detected in a horse on a premises in Maricopa County, Ariz. (Maricopa County is located in the south-central portion of the state and is home to Phoenix.) The owner of the 5-year-old gelding reported that the animal was purchased about three weeks ago. Sores appeared in the horse’s mouth in mid-April, and tests run at the USDA’s National Veterinary Services Laboratory in Ames, Iowa, confirmed the infection. Arizona was spared in the 2004 VS outbreak, when Texas had 15 cases, New Mexico had 80, and Colorado 199.

One premises in Grant County, N.M., remains quarantined where two horses are recovering from the viral blistering disease. Infected and susceptible animals remain under movement prohibition until at least 30 days after all lesions heal, and a state or federal regulatory veterinarian examines the livestock.

Vesicular stomatitis 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. Lesions usually will heal in two or three weeks. Because the signs of VS mimic those of foot-and-mouth disease (FMD), animal health officials strongly urge livestock owners and caretakers to report potential cases of VS to their private veterinary practitioner or state livestock health officials. Laboratory tests run at no charge to the producer will differentiate whether infection is caused by VS or FMD–the latter is a dreaded foreign animal disease