HELENA — The Montana Department of Livestock (MDOL) said that a bull from a Beaverhead County herd inside the state’s Designated Surveillance Area tested positive (Tuesday Aug. 19) for brucellosis and the herd is under quarantine while officials investigate .
The bull was flagged as a brucellosis suspect during required testing at a livestock market in late July, euthanized and taken to the Montana Veterinary Diagnostic Laboratory for necropsy. Tissues were sent to the U.S. Department of Agriculture’s National Veterinary Services Laboratory in Ames, Iowa, where officials grew Brucella abortus from a lymph node, the department said.
The investigation will trace animal movements and test contacts to determine whether the disease has spread to other herds. MDOL said it will work with the affected operation to minimize impacts and conduct a focused inquiry.
Montana’s DSA was established because of the risk of disease spillover from infected wildlife in the Greater Yellowstone Area. Brucellosis can cause abortions, stillbirths and newborn deaths in livestock; testing requirements aim to detect cases before animals leave the DSA and to reassure trading partners.
“While detections of brucellosis are a hardship on operations, this detection is still a reflection of the success of our state brucellosis program,” said Dr. Brenee Peterson, MDOL veterinarian. “Through the work of DSA producers and local veterinarians, we continue to detect the disease early and prevent the export of a brucellosis infected animal to one of our trading partners.”
This is the 14th brucellosis-affected herd confirmed in Montana since the DSA was established in 2010. The most recent prior detection inside the DSA was in Madison County in April 2023; previous investigations and DNA genotyping have linked past infections to wild elk and found no evidence of fence-line spread to neighboring herds.
More information from the Montana Department of Livestock is available at liv.mt.gov.
