Vaccine suggested for horses to protect against West Nile

Montana’s animal health officials are encouraging equine owners to consult with their veterinarians about vaccination for West Nile virus after a spike in the number of cases last year.

“We had 32 cases last year, the most since 2007, and the third highest total in the nation,” said assistant state veterinarian Dr. Tahnee Szymanski. “That’s concerning because the disease is highly preventable.”

No cases were reported last year in either Lincoln or Flathead counties.

Based on state Department of Livestock data, no equines that were current on vaccinations have ever contracted the disease in Montana. In contrast, one-third of the non-vaccinated equines that contracted the disease either died or had to be euthanized.

Dr. Greg Johnson, professor of veterinary entomology at Montana State University’s Department of Animal & Range Sciences, says vaccination — which is recommended as a core vaccine by the American Association of Equine Practitioners — is prudent given the virus’ unpredictably.

“It’s kind of like the flu season,” Johnson said. “We can look at the existing data and forecasts and make some guesses, but we can’t really predict what West Nile is going to do or how bad it’s going to be.”

However, with snowpack running above normal throughout much of the state, environmental conditions could be right for West Nile activity later this year.

“With all of that snowpack, it looks like we’ll have lots of water, and that can mean more mosquitoes,” he said.

A mosquito-borne disease, West Nile was first found on the east coast of the U.S. in 1999. Since then, the disease has spread westward, arriving in Montana in 2002. The disease knows no climactic or geographic boundaries in Montana, and has been found statewide.

There is no treatment for horses that contract the disease.

Any confirmed or suspected case should be immediately reported to the Montana state veterinarian’s office at (406) 444-2043.