On Dec. 24, 2025, the Montana Department of Livestock (MDOL) confirmed a positive brucellosis test in a Gallatin County cattle herd located within Montana’s Designated Surveillance Area (DSA), marking the state’s second livestock detection of 2025.
The affected herd was quarantined while an epidemiological investigation continues. The DSA was established to address disease risks posed by wildlife in the Greater Yellowstone Area. Brucellosis can cause abortions, stillbirths and neonatal losses in livestock.
Since 2010, 15 Montana herds have been affected, with prior cases traced to wild elk.
