HELENA, Mont. (AP)--The number of Montana horses known to be infected with vesicular stomatitis rose to 16 on Aug. 19 with test results still pending for numerous other horses suspected of having the infectious disease, the state veterinarian said Aug. 19.

Dr. Tom Linfield said all the cases, so far, are in the Laurel-Billings areas, from 11 different premises.

The viral disease primarily affects horses, cattle and swine.

Wyoming, Colorado, Utah, New Mexico and Arizona also have current cases of VS in horses and cattle, the state Department of Livestock official said.

Because Montana now is considered a VS-affected state, there may be restrictions for seasonal grazing permits, annual equine permits and six-month horse passports, he said.

Montana will be considered a VS-affected state until 21 days after lesions in the last affected animal have healed. As new animals are diagnosed, Linfield said, that status will be extended.

He also reiterated that animal owners and veterinarians should be aware that interstate restrictions now apply for animals being imported from a VS-affected state.

Linfield said export of Montana horses and other susceptible livestock into Canada is prohibited, and some other states are requiring the same regulations as Montana regarding VS-susceptible animals.

It's believed the virus is spread to livestock by insects, such as the sand fly and the black fly. Once introduced, it's believed the disease moves from animal to animal by exposure to saliva or fluid from ruptured lesions, Linfield said.

Date: 8/24/05