Brucellosis Discovered On Southwest Montana Ranch

Aug 24, 2017

A heifer has tested positive for the disease brucellosis on a cattle ranch near Yellowstone National Park. 

A Madison County ranch was placed under quarantine by the Montana Department of Livestock earlier this month after the infected cow was discovered during a voluntary blood test.

“She was taken to slaughter and tissues were collected," says state veterinarian Marty Zaluski. "And then those tissues were cultured positive for brucella abortus, which is the strain of brucellosis that’s found in Greater Yellowstone area elk and bison.”

The disease’s presence was confirmed on Wednesday.

Brucellosis can cause cows to abort their young, and the infected animal was discovered within Montana’s Designated Surveillance Area, a four-county zone in southwest Montana where the risk of brucellosis transmission from elk runs high.

Cattle living within the DSA are subject to mandatory vaccinations and testing prior to sale. Zaluski says this is the ninth brucellosis infection there since 2010.

“When you look at the thousands of cattle that are in that area, numerous operations, the fact that we’ve found nine cases since 2010 indicates that it’s pretty rare,” he says.

Officials are now testing the rest of the Madison County ranch’s herd for the disease, and expect to be done by the beginning of next week. The name of the ranch is not public due to confidentiality.

Montana Fish, Wildlife and Parks is proposing several amendments to existing rules addressing risk management of brucellosis transmission between elk and cattle.

These changes include the use of hunting to control the disease. A public hearing on the proposed rule amendments will be held on September 12th at 6 p.m. at the FWP regional office in Bozeman.