Bovine Tuberculosis Testing Requirements in Montana: What Ranchers Need to Know

If you own cattle, bison, or goats in Montana, bovine tuberculosis testing is not optional paperwork you can skip when it’s convenient. It’s a legal requirement tied directly to interstate movement, herd health certification, and disease traceback investigations that the Montana Department of Livestock (MDOL) takes seriously.

You’ll find that the rules shift depending on your animal’s age, species, sex, and where it’s headed next. This breakdown walks you through exactly what triggers a test, which methods regulators accept, and what happens if a result comes back positive.

What Is Bovine Tuberculosis and Why It Is Regulated in Montana

Bovine tuberculosis is caused by the bacterium Mycobacterium bovis, and it behaves differently than most livestock illnesses you’ve probably dealt with before. Bovine TB is caused by the bacteria Mycobacterium bovis, and the disease causes granulomatous lesions inside the lymph nodes, lungs, liver, spleen and skin of affected animals. The primary route of spread is aerosol transmission to other animals in close contact, and the bacteria is also capable of infecting wildlife, such as deer, and people.

What makes this disease especially tricky for you as a producer is that it hides well. Infected cattle often look completely healthy for months or years before showing any sign of illness, which is exactly why testing programs exist instead of relying on visual herd checks. You can read more about how this disease compares to other livestock illnesses on our bovine disease overview.

The human health angle matters too, though maybe less than you’d expect. Bovine TB accounts for less than 2% of tuberculosis cases in the United States. Although TB is a zoonotic disease capable of infecting people, it is not a food safety threat, thanks to a robust meat inspection program and the pasteurization of milk for retail sale, according to MDOL. If you’re curious how a related but distinct disease is handled in poultry, our avian tuberculosis guide covers that separately.

Pro Tip: Even though bovine TB rarely threatens the food supply, it can shut down interstate cattle movement fast. A single positive animal can trigger testing on every herd it’s been linked to through sale or movement records.

Montana’s TB Classification Status and Risk Zones

Every state operates under a federal classification system that determines how often and how broadly your herd needs testing. The USDA’s Uniform Methods and Rules sorts states and zones into four tiers, and the tier you fall under changes which animals must be tested during accreditation reviews.

Under this system, Accredited Free States or zones require testing of all cattle or bison 24 months of age and older, while Modified Accredited Advanced States or zones require testing of all cattle or bison 18 months of age and older. Lower-tier classifications require broader testing: Modified Accredited States or zones require testing of all cattle or bison 12 months of age and older, and Accreditation Preparatory States or zones require testing of all cattle and bison regardless of age.

Classification Tier	Minimum Age Tested	General Risk Level
Accredited Free	24 months and older	Lowest — no recent disease history
Modified Accredited Advanced	18 months and older	Low, with some monitoring needs
Modified Accredited	12 months and older	Moderate — active surveillance
Accreditation Preparatory	All ages	Elevated — building toward accreditation

Montana’s own record shows why this system exists. Montana has had a history of bovine tuberculosis dating back to the 1990s, and bovine TB was detected in at least six game farms in Montana in the early 1990s, with positive farmed fallow deer detected in Sheridan and Richland counties and positive farmed elk detected in Granite, Park, Bighorn, and Carter counties.

The state went decades without a confirmed livestock case until a Blaine County herd broke that streak. Bovine tuberculosis was confirmed in a Montana beef herd for the first time in decades when MDOL confirmed TB in a Blaine County herd following detection of the disease in a cow at slaughter. Wildlife surveillance has also picked up occasional cases outside cattle herds: sporadic cases of the disease have been reported in free-ranging wildlife in Montana, New York, Minnesota, Indiana, and Ontario.

Important Note: A state’s classification status can shift after a confirmed case triggers investigation. Because status affects testing frequency and interstate shipping requirements, confirm Montana’s current standing directly with MDOL’s Animal Health Bureau before planning a shipment or herd test.

Who Must Test and Which Animals Are Covered in Montana

Testing obligations in Montana depend heavily on what your animal is doing and where it’s going, not just its species. A rodeo bull, a dairy heifer, and a boer goat destined for exhibition all fall under different rules.

• Rodeo and roping cattle: Animals for rodeo or roping require one negative TB test within 12 months prior to entry under ARM 32.3.212.
• Sexually intact dairy cattle: All sexually intact animals over 2 months of age require one negative TB test within 60 days prior to entry, or an alternative accepted status.
• Goats: Sexually intact goats over 2 months of age need one negative TB test within 60 days prior to importation under ARM 32.3.214, unless an exhibition-only statement applies.
• Herds linked to a positive animal: Bovine TB testing is required in a herd whenever a link has been established between that herd and a positive animal through movement or sale records.

That last bullet is the one most producers overlook. You don’t have to have a sick-looking animal to get a testing order — a paper trail connecting your herd to an infected animal elsewhere is enough to bring an inspector to your gate. This is one of several reasons why livestock biosecurity practices in Montana matter well beyond your own property line, and why keeping accurate movement and sale records lines up with Montana’s brand inspection requirements, which create much of that paper trail in the first place.

Approved TB Testing Methods in Montana

Not every test carries the same regulatory weight, and knowing which one your vet will use helps you plan for handling time. The standard method for tuberculosis detection in live animals is the caudal fold test, where a small amount of TB antigen is injected intradermally and re-assessed after 72 hours.

Timing matters here in ways that catch some producers off guard. A positive response usually begins within 8 to 12 hours and peaks about 72 hours after injection, which is why your animals go through the chute twice — once for injection, once for the read. Regulators also require a specific product for this test: only bovine purified protein derivative tuberculin, licensed by USDA, may be used for official testing.

A caudal fold reaction isn’t a final diagnosis by itself. The caudal-fold test is used as a presumptive diagnostic procedure, and animals classified as suspect must be evaluated further by the comparative cervical test, gamma interferon test, or sent directly to slaughter under permit. False positives do happen, though not often: these false-positive responses may occur in 1 to 5% of tested cattle.

Test Method	Purpose	Typical Timeframe
Caudal Fold Test (CFT)	Initial screening / presumptive result	72-hour read after injection
Comparative Cervical Test (CCT)	Follow-up on suspect CFT results	Several days
Gamma Interferon Assay	Confirmatory blood-based test	Same-day lab processing
PCR Confirmation	Rapid molecular confirmation	Roughly 3 hours, compared to up to six weeks for classical culture

If you’re comparing this process to other required tests you’ve handled before, it runs on a similar logic to the EIA Coggins test requirements in Montana for horses — a screening test first, followed by confirmatory testing only when something flags.

Interstate and Intrastate Movement Testing Requirements in Montana

Moving cattle across state lines into Montana brings its own paperwork stack, and TB testing is only one piece of it. According to Montana’s Department of Livestock import requirements, most classes of cattle and goats need proof of a recent negative test alongside a valid health certificate.

A health certificate must be issued within 30 days of entry under ARM 32.3.202 and ARM 32.3.206, and an import permit is only required for handwritten Certificates of Veterinary Inspection issued on paper, not for electronic ones. Dairy cattle face a stricter standard: an import permit is required for all dairy cattle CVIs entering the state, regardless of format.

Within Montana, movement across county lines doesn’t typically trigger a fresh TB test on its own, but it does trigger a separate compliance step you shouldn’t skip. Every animal crossing a county line or leaving Montana still needs a valid brand inspection alongside its health paperwork. If you’re also transporting animals that need rabies documentation for exhibition or sale, it’s worth reviewing Montana’s rabies vaccine requirements at the same time, since inspectors often check multiple health documents in a single stop.

Pro Tip: Keep your TB test results, health certificate, and brand inspection paperwork together in one folder before transport. Inspectors and law enforcement can request any of these documents on the spot, and missing paperwork is treated as a violation even if the underlying test was done correctly.

What Happens When a Suspect or Positive Result Occurs in Montana

A “suspect” result isn’t a diagnosis — it’s a trigger for more testing, and the clock starts immediately. Accredited veterinarians must immediately report every suspected or diagnosed bovine TB case promptly to both the Assistant District Director and the State Animal Health Official.

From there, the animal moves into a defined evaluation path. As noted earlier, a suspect caudal fold reaction gets escalated to a comparative cervical test, gamma interferon assay, or direct slaughter under permit before anyone calls it confirmed. Montana’s 2021 Blaine County case shows how far the response can extend once a case is confirmed rather than merely suspected: finding bovine TB in the herd triggered a full epidemiological investigation to evaluate the extent of disease, including the testing of adjacent herds and herds that had shipped animals into or received animals from the source herd.

That’s the part many producers underestimate — a positive result rarely stays contained to one property. Anyone who bought, sold, or grazed alongside the affected herd within the relevant window can expect a call from MDOL asking to test their own animals too.

Quarantine and Herd Depopulation Rules in Montana

Once TB is confirmed rather than suspected, your options narrow considerably. Options for TB-affected herds are limited and include whole herd depopulation, or extended quarantine while the herd is tested repeatedly through a test-and-removal approach.

Neither option is painless, but depopulation comes with a financial backstop you should know about. Herds subject to whole herd depopulation are reimbursed, or indemnified, by the federal government based upon an assessment of the animals’ value. Test-negative animals from depopulated herds can still go through slaughter channels to salvage the meat of the animal, so a negative result doesn’t automatically mean a total loss.

The geographic reach of a quarantine order can surprise neighboring producers. All livestock herds within a 10-mile radius will be tested within 6 months of any diagnosis of bovine tuberculosis. Getting back to a clean bill of health takes more than one clean test, too: to qualify for Accredited herd status, a herd must pass at least two consecutive official tuberculosis tests conducted within an interval of 9 to 15 months with no evidence of bovine tuberculosis.

This kind of sustained testing burden is exactly why proactive biosecurity planning pays off before you’re ever in a quarantine radius. Limiting nose-to-nose contact at shared water sources and tracking every animal that comes onto your property reduces your odds of ending up on someone else’s traceback list.

Penalties for Non-Compliance in Montana

Skipping a required test or moving cattle without proper documentation carries real financial and legal consequences in Montana, not just a warning letter. Violations of Montana’s livestock laws can result in significant penalties, deterring non-compliance, with penalties ranging from financial to criminal charges depending on the infraction’s severity.

Because TB testing compliance is checked alongside brand inspection and movement documentation, the penalty structure often overlaps with Montana’s broader livestock transport rules. Transporting livestock without a permit can result in fines up to $500 per violation, and non-compliance with health and safety regulations tied to livestock movement can incur fines ranging from $100 to $1,000.

Border compliance gets checked immediately, too. If animals are not in compliance when they arrive in Montana, the Montana Department of Livestock can refuse to let them unload, and failure to have the proper documents is itself a violation of Montana law that can result in a citation and fine. For a closer look at how these enforcement mechanics work in practice, our brand inspection requirements guide breaks down the misdemeanor classifications and repeat-offense consequences in more detail.

Important Note: This article summarizes state and federal animal health regulations for general informational purposes. Testing requirements, classification statuses, and fee schedules can change; confirm current rules with the Montana Department of Livestock or a licensed accredited veterinarian before moving or testing animals.

Staying ahead of Montana’s bovine tuberculosis testing requirements comes down to a few habits: know your animal’s classification tier, keep test results current before any move, and never separate your health paperwork from your brand inspection documents during transport. Given how quickly a single traceback investigation can expand to neighboring herds, treating TB testing as routine maintenance rather than an occasional hurdle is the difference between a quick chute session and a multi-month quarantine.