HELENA — Montana livestock officials have expanded the area of the state where cattle are required to be vaccinated against the disease brucellosis, which is carried by elk and bison.
The Department of Livestock announced Thursday that ranchers in six more counties have to vaccinate all sexually intact cows and domestic bison 12 months of age. Those counties are Big Horn, Broadwater, Carbon, Jefferson, Stillwater and Sweet Grass. The vaccination program continues in Gallatin, Madison, Park and Beaverhead counties.
State brucellosis veterinarian Eric Liska says expanding the vaccination area provides protection against infected wildlife that might move into those areas.
Brucellosis causes animals to abort their young. It's been eradicated nationwide except in and around Yellowstone National Park.
In a smaller Designated Surveillance Area near the park, cattle also must be tested for brucellosis before being sold or moved.