On June 4, 2004, the National Veterinary Services Laboratories (NVSL) in Ames, IA, confirmed the finding of vesicular stomatitis (VS) in horses at one premises in New Mexico.

VS is a viral disease that primarily affects horses, cattle, and swine. The virus that causes VS has a wide host range. VS also occasionally affects sheep and goats. In affected livestock, VS virus causes blisterlike lesions to form in the mouth and on the dental pad, tongue, lips, nostrils, hooves, and teats. These blisters swell and break, leaving raw tissue that is so painful that infected animals generally refuse to eat and drink and show signs of lameness. Severe weight loss usually follows, and in dairy cows, a severe drop in milk production commonly occurs. Affected dairy cattle can appear to be normal and will continue to eat about half of their feed intake.

On May 26, 2004, a foreign animal disease investigation was initiated at a farm in Carlsbad, NM due to a report of tongue lesions in two horses on the premises. There are two additional horses, two steers, and some sheep and goats on the infected premises that show no signs of lesions. Serum was taken from all horses on the premises and submitted to NVSL for testing. After the first round of testing, one horse was complement fixation (CF) positive and three horses were cELISA positive for antibodies to the New Jersey strain of VS virus.

The second set of serum samples from the horses was received by NVSL on June 3, 2004. Results from the second set of serum samples were consistent with the case definition for VS that is based on compatible clinical signs and appropriate laboratory confirmation, which may include virus isolation or a four-fold increase in complement fixation (CF) or serum neutralization titer in paired sera collected at least seven days apart. The infected premises has been placed under quarantine. There is no history of exposure and no recent herd additions. Veterinary Services and New Mexico Department of Agriculture will continue to monitor the situation and conduct response activities in an effort to minimize trade restrictions