MDOL reminds producers of new brucellosis vaccination rules

Helena, Mont. – The Montana Department of Livestock (MDOL) is reminding producers that all sexually intact female cattle and domestic bison 12 months of age and older in Beaverhead, Big Horn, Broadwater, Carbon, Gallatin, Jefferson, Madison, Park, Stillwater, and Sweet Grass Counties must be vaccinated against brucellosis. This includes cattle that enter these counties seasonally.

In October of 2018, MDOL adopted changes to Administrative Rules of Montana (ARM) 32.3.436 pertaining to brucellosis vaccination. The change increased the number of counties in Montana in which brucellosis vaccination is required from four to ten. The original rule was adopted in 2010.

This rule includes cattle and domestic bison born in 2018. If you reside or run cattle in any of the 10 counties and have not historically vaccinated females, you should contact your veterinarian to have females vaccinated and to discuss options for unvaccinated adult cows in your herd.

“Unvaccinated cows born prior to 2018 must receive the vaccine by January of 2021. This grace period allows producers to schedule vaccination when cows are not pregnant.” said Eric Liska, Brucellosis Program Veterinarian with MDOL. Vaccination of pregnant animals is not recommended due to the risk of abortion.

In addition to the new counties, the rule no longer requires vaccination to be completed by the end of December and no longer specifies calfhood vaccination. This gives producers more options for the management of replacement heifers and allows animals to be vaccinated as adults.

The mission of the Montana Department of Livestock is to control and eradicate animal diseases, prevent the transmission of animal diseases to humans, and to protect the livestock industry from theft and predatory animals. For more information on the Montana Department of Livestock, visit

–Montana Department of Livestock