Brucellosis Found in MT Domestic Bison Herd


Brucellosis has been found in a domestic bison on the Flying D Ranch near Bozeman, the Montana Department of Livestock reported today.

Two other bison at the ranch, which is currently quarantined, remain suspects. The Flying D bison herd is geographically separate from the Green Ranch, which received bison from the cooperative USDA-Montana Fish, Wildlife & Parks quarantine facility last year. Those 86 Yellowstone Park bison remain disease-free. 

State Veterinarian Dr. Marty Zaluski explained to us that management practices further ensure that separation.

The brucellosis-infected bison, a 7-year-old cow, was identified as a suspect during routine disease testing. Cultures performed at the National Veterinary Services Laboratories (NVSL) in Ames, Iowa, confirmed the presence of Brucella abortus, the causative agent of brucellosis, in the suspect bison.

Dr. Zaluski said the discovery of the infected bison is not likely to impact the state’s brucellosis status.

“USDA is currently reviewing its approach to brucellosis management nationwide,” Zaluski said. “The proposed concept would de-emphasize state status and allow brucellosis to be managed on a case-by-case basis.”        

Zaluski said that the Flying D’s 4,600-head bison herd is “intensively managed,” with practices that include Official Calfhood Vaccination and annual brucellosis testing. 

An epidemiological investigation, which is already underway, should shed more light on exactly where the infection came from.

“In previous cases, extensive testing indicated that elk, not cattle or bison, were the likely source of the infections,” he said.

Brucellosis-infected elk have been found on the Flying D in previous years.

After going more than 30 years without a case of brucellosis, the state lost its brucellosis-free status when the disease was found twice within a 12-month period in 2007 and 2008. The department responded with the Brucellosis Action Plan and later, the Designated Surveillance Area, resulting in the fastest ever reinstatement of a state’s brucellosis class-free status. 

In a Northern Ag Network interview, Dr. Zaluski told us that depopulation was not a discussion at this point.  That, he told us, is the case because it would neither be economical or sensible.  If depopulated and replaced with a clean herd, the risk would still remain.  This, he says, would also likely be true for an infected cattle herd as changes are now being made on the federal level.  This was showcased in the most recent brucellosis positive case in Idaho.

Montana Brucellosis Timeline

  • 1934 – The U.S. Department of Agriculture initiates a national brucellosis eradication program.
  • 1952 – Montana begins an aggressive program to eliminate brucellosis from its livestock.
  • 1985 – After more than three decades of effort and an expenditure of more than $30 million by the state’s livestock producers, the state obtains brucellosis-free status.
  • 2000 – The Interagency Bison Management Plan (IBMP) is implemented.
  • 2007 (May) – Brucellosis is found in a Carbon County cattle herd.
  • 2008 (May) – Brucellosis is found in a Park County cattle herd.
  • 2008 (September) – The state loses its brucellosis-free status.
  • 2008 (November) – The Brucellosis Action Plan is approved.
  • 2009 (July) – The USDA reinstates Montana’s brucellosis class-free status.
  • 2010 (January) – The Brucellosis Action Plan sunsets; the Designated Surveillance Area is implemented.
  • 2010 (November) – A brucellosis-infected bison is found on the Flying D Ranch in Gallatin County.

Source:  Montana Department of Livestock

Posted by Haylie Shipp


Notify of
Inline Feedbacks
View all comments
Would love your thoughts, please comment.x