Brucellosis Laws and Regulations in Montana: Classification, Testing, and Compliance Rules

Montana sits at the center of the United States brucellosis challenge. Brucellosis in the United States is primarily a geographic problem concentrated in the Greater Yellowstone Area of Idaho, Montana, and Wyoming, where B. abortus remains endemic in wild elk and bison populations, and occasional spillover into livestock herds still occurs. That reality shapes every layer of the state’s regulatory framework — from which counties require mandatory vaccination to how animals must be identified before leaving a high-risk zone.

If you raise cattle or domestic bison in Montana, import breeding stock, or move animals across county or state lines, you have specific legal obligations under both state and federal brucellosis law. This guide covers each major regulatory layer: what the disease is and why Montana regulates it so closely, how the state is classified, what vaccination and testing rules apply to your herd, how movement is controlled, what you must report, and what penalties follow a violation.

What Is Brucellosis and Why It Is Regulated in Montana

Brucellosis is the contagious, infectious, and communicable disease of animals and humans caused by bacteria of the genus Brucella — specifically Brucella abortus, Brucella suis, or Brucella melitensis, referred to collectively as brucella organisms. The disease does not discriminate narrowly by species. An “animal” subject to brucellosis regulation includes any quadruped capable of becoming infected, including members of the bovine, porcine, canine, ovine, bison (wild or domestic), caprine, or feline species, or the genus Cervidae.

For cattle and bison producers, the consequences are primarily reproductive. In its principal animal hosts, brucellosis causes loss of young through spontaneous abortion or birth of weak offspring, reduced milk production, and infertility. There is no economically feasible treatment for brucellosis in livestock. That fact alone explains why prevention and surveillance — not treatment — drive the entire regulatory structure.

The human health dimension makes brucellosis a dual-mandate concern for state regulators. In humans, brucellosis initially causes flu-like symptoms, but the disease may develop into a variety of chronic conditions, including arthritis. Humans can be treated for brucellosis with antibiotics. Because the bacteria can spread through contact with infected animals, their tissues, or unpasteurized milk, Montana’s regulatory program is designed to protect both livestock producers and the broader public.

Montana’s proximity to Yellowstone National Park intensifies the regulatory stakes. The Montana Department of Livestock mitigates the spread of this disease, and the state has worked hard to implement systems and practices to control and prevent its spread. The Department of Livestock has an established quarantine facility near Yellowstone National Park where Park bison are held and tested to ensure they are brucellosis-free before they can be transferred to new locations. This infrastructure reflects the ongoing spillover risk that wildlife reservoirs pose to domestic herds.

Montana’s Brucellosis Classification Status

Montana’s classification history is a cautionary tale that shapes current law. Prior to 2008, Montana was classified as a Class Free State. On May 18, 2007, a brucellosis-affected herd was confirmed in Montana. The state took immediate measures to maintain its Class Free status, but on June 9, 2008, another brucellosis-affected herd was confirmed.

USDA APHIS amended the brucellosis regulations concerning interstate movement of cattle by changing the classification of Montana from Class Free to Class A, determining that Montana no longer met the standards for Class Free status. This action was necessary to prevent the interstate spread of brucellosis. That reclassification had immediate and lasting economic consequences.

The undetected disease spread outside of Montana’s Designated Surveillance Area (DSA) could jeopardize Montana’s federal brucellosis Class Free status, and in 2008, a loss of brucellosis Class Free status was estimated to have cost Montana’s producers up to $11.5 million annually. That figure explains why the state has invested heavily in its DSA program and why compliance is treated as a shared economic interest, not just a legal formality.

The brucellosis regulations contained in 9 CFR Part 78 provide a system for classifying states or portions of states according to the rate of Brucella infection present and the general effectiveness of a brucellosis control and eradication program. Under that federal framework, Montana’s Class A designation means that movement restrictions apply to cattle and bison leaving the state — a direct consequence of the 2008 reclassification that remains in effect.

Vaccination Requirements for Cattle and Bison in Montana

Montana’s vaccination requirements are geographically targeted, applying most strictly to counties within or adjacent to the Designated Surveillance Area. All sexually intact female cattle or domestic bison 12 months of age or older in Beaverhead, Big Horn, Broadwater, Carbon, Gallatin, Jefferson, Madison, Park, Stillwater, and Sweet Grass counties must be official vaccinates.

Official vaccinates are calfhood or adult vaccinates (AV). Vaccination requirements apply to resident female cattle as well as cattle seasonally grazing in these counties. This means that even if your home operation is outside these counties, you become subject to the vaccination mandate the moment your animals graze within the listed areas during the risk season.

The current rule represents a significant expansion from prior requirements. Prior to this rulemaking, only cattle and domesticated bison in Gallatin, Madison, Park, and Beaverhead counties were required to be vaccinated. Beyond the addition of new counties, the rule also moves away from December 1 as the cutoff date for completion of vaccination and no longer specifies that animals be calfhood vaccinates, giving producers more options for the management of replacement heifers and allowing animals to be vaccinated as adults.

• Official Calfhood Vaccinate (OCV): An animal vaccinated at an official calfhood vaccination eligible age with an approved brucella vaccine using approved procedures.
• Official Adult Vaccinate (AV): A sexually intact animal of the genus Bos or domestic bison vaccinated with an approved brucella vaccine, using approved procedures, and of an age older than that permitted for official calfhood vaccination.
• Approved Vaccine: An approved brucella vaccine is a brucella product approved by and produced under license of the United States Department of Agriculture for injection into cattle or bison (wild or domestic) to enhance their immune response to brucella.

For adult vaccination of Montana animals, a negative brucellosis test within 30 days prior to adult vaccination is required. The animal must be vaccinated with a full dose (2cc) of regularly reconstituted RB51 vaccine.

Females managed at any time during the risk period in the DSA can be booster vaccinated for brucellosis if the risk warrants it. Producers who have not previously vaccinated their replacement females should consult with a licensed veterinarian to schedule vaccinations and discuss options for unvaccinated adult females already in the herd.

Testing Requirements for Cattle and Bison in Montana

Testing requirements in Montana are concentrated within the Designated Surveillance Area and apply at key trigger points — movement and change of ownership. All sexually intact cattle and domestic bison must be tested for brucellosis within 30 days prior to leaving the DSA or changing ownership. Tests run on blood drawn after August 15 are valid for movement or change of ownership until February 15 of the following year.

Test-eligible animals means sexually intact cattle or domestic bison twelve months of age or older. An “official brucellosis test” is a laboratory protocol for the brucellosis classification of animals as approved by the administrator. Only tests conducted through approved protocols and reported on official documentation satisfy the regulatory requirement.

Several exemptions from the pre-movement testing requirement exist within the DSA framework:

• Animals moving to an approved Montana livestock market that will be tested at the market prior to sale.
• Animals destined for exhibition or veterinary care within the DSA that will not be commingled with other livestock, will remain in confinement for the duration of the event or treatment, and will depart within 10 days of arrival.
• Animals utilizing the DSA during the low-risk period — entering the DSA after July 15 and leaving prior to January 15.
• Animals entering the DSA for summer grazing may be tested upon return to their origin location. Testing must be done within 10 days, and animals may not be commingled with other livestock until testing is complete.

Montana also provides financial relief to offset testing costs. Costs of DSA testing and adult vaccination are compensated for veterinarians and producers on a state fiscal year schedule (July 1 through June 30) and are dependent upon availability of funds. Rates are determined by MDOL and are subject to change. Producers may request reimbursement for DSA-related brucellosis testing at a rate of $2 per head.

For animals entering Montana from other states, the import requirements include documentation of herd history. Whole herd TB and/or brucellosis test charts for the previous five to six whole herd tests, or annual whole herd inventory verification for the previous five years, along with bills of sale for all animals sold during the 60 months prior to importation into Montana, are required.

Interstate and Intrastate Movement Rules in Montana

Montana’s movement rules operate on two tracks: federal requirements that govern movement out of the state, and state-level DSA rules that govern movement within Montana’s high-risk counties.

Interstate Movement

Because Montana holds Class A status under 9 CFR Part 78, interstate movement of cattle and bison is subject to federal testing requirements. A reclassification from Class Free to Class A status with respect to brucellosis results in movement restrictions. Specifically, all bovine animals moved interstate, except those moving directly to slaughter or to quarantined feedlots, must test negative to a brucellosis test 30 days prior to interstate movement.

Neighboring states may impose additional conditions on animals originating from Montana’s DSA counties. North Dakota’s State Board of Animal Health recognizes Montana’s brucellosis-free status with the exception of cattle and bison from seven southwestern Montana counties. The board issued an order limiting testing requirements to cattle and bison from Beaverhead, Carbon, Gallatin, Madison, Park, Sweet Grass, and Stillwater counties. Animals from those counties that must be tested include females 18 months of age or older, or that have calved or are near calving, as well as bulls 12 months and older. The order requires that any cattle and bison entering North Dakota be negative to an official test for brucellosis 30 days prior to entry.

Before moving animals to any other state, you should verify the destination state’s specific import requirements, as they may be more restrictive than the baseline federal standard. For a comparison of how other states structure their brucellosis movement rules, see the brucellosis laws in Michigan and brucellosis laws in Missouri.

Intrastate Movement Within the DSA

Cattle and domestic bison that utilize the DSA are subject to all brucellosis DSA regulations. DSA regulations include brucellosis testing prior to a change of ownership and movement, as well as vaccination and identification requirements.

Identification is a non-negotiable component of DSA movement compliance. All sexually intact cattle and domestic bison, regardless of age, leaving the DSA must be officially identified. Official Individual Identification is the unique individual identification of cattle or domestic bison as approved by the administrator.

For feeder heifers specifically, a limited exception applies. DSA-born heifers under 12 months of age moving for feeding-only purposes may be identified with a NUES (metal) tag.

Montana also allows producers to establish management agreements that can create tailored variances to standard DSA requirements. A brucellosis prevention and surveillance herd management agreement is a document outlining brucellosis mitigation and surveillance practices that will be or have been instituted by an individual DSA producer or DSA production unit. These management agreements may outline variances to Montana brucellosis requirements. A management agreement is mutually agreed upon by the producer and the Department of Livestock and should be reviewed every five years or earlier if requested by the herd owner or DOL.

Reporting and Quarantine Requirements in Montana

Montana’s brucellosis program relies on prompt reporting to detect transmission events before they spread. Brucellosis is a reportable disease under Montana law, meaning that veterinarians, laboratories, and producers who identify or suspect a case have an affirmative obligation to notify the appropriate authorities.

The Montana legislature specifies the roles and responsibilities of the Montana Department of Public Health and Human Services through the Montana Code Annotated. In relation to the reporting and control of communicable disease, MCA 50-1-202(p) grants MT-DPHHS the authority to adopt and enforce rules regarding the reporting and control of communicable diseases. On the livestock side, the Montana Department of Livestock (MDOL) administers the parallel animal-health reporting structure under MCA Title 81.

When a suspected or confirmed brucellosis case is identified in a livestock herd, the MDOL has authority to place the affected animals under quarantine. Upon request of the owner of an infected herd, disease control activities may be conducted with the assistance and participation of a deputy state veterinarian selected and paid for by the owner. An official epidemiological report must be prepared that specifies the methods necessary to eradicate the disease and includes a timetable for the process.

Quarantine authority extends to animals that enter Montana in violation of entry rules. Animals that enter the state of Montana without a valid health certificate or permit, or in violation of any rules of the Department of Livestock, shall be held in quarantine at the risk and expense of the owner until released by an authorized representative of the Department of Livestock, Animal Health Division. The quarantine may be released only after the department has been satisfied, by appropriate means, that the animals are not infected with disease.

The DSA program itself functions as a continuous surveillance system. DSA regulations and producer compliance have allowed for early disease detection when a periodic transmission from wildlife to livestock does occur. This success promotes trading partner confidence in the disease-free status of Montana’s livestock.

Variances and exceptions to standard DSA requirements are available on an individual basis. Other variances or exceptions to requirements will be considered on an individual basis by the brucellosis program coordinator. If you would like to set up a management agreement to establish a variance, contact the MDOL at 406-444-2976.

Penalties for Brucellosis Violations in Montana

Violations of Montana’s brucellosis laws carry consequences that span financial penalties, criminal liability, forced quarantine, and potential loss of indemnity eligibility. The penalty structure is designed to deter the specific behaviors — unreported reactors, movement of untested animals, falsified records — that pose the greatest risk to the state’s disease control program.

Financial Penalties

Violations of Montana’s livestock laws can result in significant penalties, deterring non-compliance and ensuring adherence to the legal framework. Penalties range from financial to criminal charges, depending on the infraction’s severity. Financial penalties are common for non-compliance. Transporting livestock without a permit can result in fines up to $500 per violation. Non-compliance with health and safety regulations can incur fines from $100 to $1,000. Repeat offenders may face increased fines.

Criminal Liability

In severe cases, violations can lead to criminal charges. Under MCA Title 81, Chapter 8, criminal penalties may be pursued for actions threatening public health or involving misconduct, such as livestock theft or falsifying records. Falsifying vaccination or testing records is among the most serious categories of violation because it directly undermines the integrity of the state’s surveillance system.

Quarantine and Condemnation

Beyond fines and criminal exposure, a brucellosis violation can trigger mandatory quarantine of your entire herd at your own expense. As noted above, animals that enter Montana without a valid health certificate or permit, or in violation of any rules of the Department of Livestock, shall be held in quarantine at the risk and expense of the owner. Quarantine costs accumulate quickly and can far exceed the underlying fine for the original violation.

If brucellosis is confirmed in a herd, depopulation may be required as part of the eradication plan. While federal and state indemnity programs exist to compensate producers for condemned animals, noncompliant producers may forfeit eligibility for those payments — compounding the financial impact of a violation.

Statewide Consequences of Individual Noncompliance

The stakes of individual violations extend beyond the producer directly involved. Undetected disease spread outside of Montana’s DSA could jeopardize Montana’s federal brucellosis Class Free status. In 2008, a loss of brucellosis Class Free status was estimated to have cost Montana’s producers up to $11.5 million annually. A single compliance failure that allows undetected spread can trigger regulatory consequences that affect every cattle and bison producer in the state.

If you operate livestock in Montana, staying current with MDOL guidance is essential, as DSA boundaries and vaccination county lists have expanded multiple times since 2009 and may continue to evolve. You can also explore Montana’s broader animal law landscape through related guides, including hunting laws in Montana, goat ownership laws in Montana, and backyard chicken laws in Montana. For brucellosis compliance in other states, see the guides on brucellosis laws in Nevada and brucellosis laws in Michigan.

Conclusion

Montana’s brucellosis regulatory framework is one of the most detailed in the country — a direct reflection of the state’s ongoing exposure to wildlife reservoirs in and around Yellowstone. If you raise cattle or domestic bison in Montana, your compliance obligations depend heavily on where your animals are located and how they move.

The key points to keep in mind are these: Montana holds Class A status at the federal level, which triggers interstate testing requirements. Within the state, the DSA covers ten counties where mandatory vaccination and pre-movement testing apply to all sexually intact female cattle and bison 12 months of age or older. Identification is required for all sexually intact animals leaving the DSA. Quarantine is immediate and at the owner’s expense for animals that enter the state in violation of import rules. And penalties — financial, criminal, and administrative — apply to a wide range of violations, with the most serious consequences reserved for falsified records and unauthorized movement of quarantined animals.

For the most current DSA boundary maps, reimbursement rates, and management agreement procedures, contact the Montana Department of Livestock Animal Health Bureau directly at 406-444-2976 or by email at livpermits@mt.gov. Regulations in this area have changed multiple times and may continue to evolve as wildlife brucellosis distribution shifts. Verify current requirements with MDOL before each movement season. You may also find it useful to review related Montana animal law topics such as kennel zoning laws in Montana, beekeeping laws in Montana, and roadkill laws in Montana.