Michigan Brucellosis Rules for Cattle and Bison: Testing, Vaccination, and Interstate Movement

Brucellosis is one of the most economically damaging livestock diseases in the United States, and Michigan takes its prevention seriously. Whether you raise cattle, bison, or both, understanding the state’s brucellosis regulations is not optional — it is a legal requirement that directly affects how you buy, sell, move, and manage your animals.

This guide walks you through Michigan’s current brucellosis classification, vaccination and testing mandates, movement rules, reporting obligations, and the penalties you face if you fall out of compliance. Knowing these rules protects your herd, your neighbors’ herds, and your livelihood.

What Is Brucellosis and Why It Is Regulated in Michigan

Brucellosis is a highly contagious bacterial disease caused by Brucella abortus, which primarily infects cattle and bison but can also spread to other livestock and humans. In animals, the disease triggers late-term abortions, stillbirths, reduced milk production, and infertility — all of which translate directly into financial losses for producers. In people, infection causes a flu-like illness known as undulant fever that can become chronic and debilitating.

Because Brucella abortus spreads through contact with infected birth fluids, aborted fetuses, and unpasteurized milk, the disease moves quickly through a herd and across state lines if movement is not controlled. That public health dimension — the risk of human infection through raw dairy products or occupational exposure — is precisely why federal and state governments regulate brucellosis so aggressively.

Michigan’s authority to regulate brucellosis flows from the Michigan Animal Industry Act (Act 466 of 1988), which grants the Michigan Department of Agriculture and Rural Development (MDARD) broad powers to establish disease control programs, mandate testing and vaccination, impose quarantines, and enforce penalties. Federal oversight is provided by the USDA Animal and Plant Health Inspection Service (APHIS), which sets national standards that Michigan must meet to maintain its disease-free classification.

Key Insight: Brucellosis is classified as a zoonotic disease, meaning it can transfer from animals to humans. This dual threat to animal agriculture and public health is why regulatory requirements are stricter than for many other livestock diseases.

For a broader look at how animal disease regulations intersect with other Michigan animal laws, the overview of Michigan pet and animal laws provides useful context on how the state structures its regulatory framework.

Michigan’s Brucellosis Classification Status

Michigan currently holds a Class Free designation under the USDA APHIS National Brucellosis Eradication Program. This is the highest possible status, meaning the state has no known established brucellosis infection in its domestic cattle or bison herds. Maintaining this status is not passive — it requires continuous surveillance, mandatory testing of certain animal classes, and strict movement controls.

The Class Free designation matters enormously for producers. It determines which animals you can import into Michigan, which animals you can ship out of state without additional testing burdens, and whether your operation qualifies for certain federal indemnity programs if an outbreak ever occurs.

However, Michigan’s free status is complicated by a well-documented wildlife reservoir. The Greater Yellowstone Area is the most publicized example nationally, but Michigan has its own concern: white-tailed deer and elk in the northern Lower Peninsula and the Upper Peninsula have historically tested positive for Brucella abortus. The Michigan DNR and MDARD jointly monitor this wildlife interface, and cattle or bison operations in high-risk areas may face additional surveillance requirements as a result.

Important Note: Even though Michigan holds Class Free status, producers in counties with documented wildlife brucellosis exposure may be subject to enhanced monitoring requirements. Contact MDARD directly to determine whether your county falls within a designated surveillance zone.

You can review current national herd classification data through the USDA APHIS Brucellosis Program, which publishes state-by-state status updates and program requirements.

Vaccination Requirements for Cattle and Bison in Michigan

Michigan does not currently mandate universal brucellosis vaccination for all cattle and bison under standard conditions, given its Class Free status. However, vaccination remains a critical tool in the state’s disease prevention strategy, and specific rules govern who may vaccinate, which animals qualify, and which vaccines are approved.

The only federally approved brucellosis vaccine currently in use in the United States is Strain RB51, a live, attenuated strain of Brucella abortus. It replaced the older Strain 19 vaccine and is administered by or under the direct supervision of an accredited veterinarian. You cannot legally purchase or administer RB51 yourself — only licensed, USDA-accredited veterinarians are authorized to handle and apply this vaccine.

• Eligible animals: Female cattle and bison between 4 and 12 months of age (calfhood vaccination window)
• Official vaccination tattoo: Vaccinated animals receive an official tattoo in the right ear identifying the vaccination date and the veterinarian’s identification number
• Shield tag: A yellow USDA shield tag is placed in the right ear at the time of vaccination
• Adult vaccination: In certain outbreak or high-risk circumstances, adult vaccination may be authorized by state and federal officials, but this is not routine

Pro Tip: Keep all vaccination records, including the veterinarian’s certificate and the official tattoo documentation, with your herd health files. These records are required when you move animals across state lines and during any regulatory inspection.

If Michigan’s disease status were to change — for example, if a confirmed herd infection were detected — MDARD has the authority under the Animal Industry Act to implement mandatory vaccination programs in affected areas or statewide. Understanding how the biology of brucellosis drives these policy decisions helps you appreciate why the vaccination protocols are structured the way they are.

Testing Requirements for Cattle and Bison in Michigan

Testing is the backbone of Michigan’s brucellosis surveillance system. Even with Class Free status, the state is required by federal program standards to conduct ongoing testing to verify that the herd population remains free of infection. The specific testing requirements that apply to your operation depend on the type of animals you own, what you plan to do with them, and where they are located.

The primary diagnostic test used in Michigan is the brucellosis card test, often paired with the Standard Plate Test (SPT) or Competitive ELISA for confirmatory purposes. All official testing must be performed by USDA-accredited veterinarians or state-approved laboratories. You cannot submit samples to an unapproved laboratory and expect the results to satisfy regulatory requirements.

The following categories of cattle and bison are subject to mandatory testing requirements:

1. Slaughter surveillance: A statistically determined percentage of adult female cattle and bison presented at federally inspected slaughter plants must be tested as part of the national surveillance program
2. Change of ownership: Sexually intact cattle and bison over 6 months of age may require a negative brucellosis test before sale depending on the destination state’s requirements and the class of animal
3. Interstate movement: Animals moving out of Michigan to certain states may require a negative test within a specified timeframe prior to shipment (see the movement section below)
4. Quarantined herds: All animals in a quarantined herd must be tested as directed by MDARD, with retesting at intervals determined by the investigation
5. Exposed animals: Any animal known or suspected to have been exposed to a brucellosis-positive animal must be tested immediately upon notification

Common Mistake: Producers sometimes assume that because Michigan is a Class Free state, no testing is required at all. This is incorrect. Slaughter surveillance, movement testing, and exposure testing requirements remain active regardless of the state’s overall classification status.

For the most current testing protocols and approved laboratory information, consult the USDA APHIS Brucellosis Uniform Methods and Rules, which establishes the federal standards that Michigan’s program must follow.

Interstate and Intrastate Movement Rules in Michigan

Moving cattle and bison — whether within Michigan or across state lines — triggers a specific set of brucellosis-related requirements. Getting these rules wrong can result in shipment rejection, quarantine of your animals at the destination, and significant financial penalties. Understanding the distinction between interstate and intrastate movement is your starting point.

Interstate movement refers to any shipment of cattle or bison from Michigan to another state. The requirements you must meet depend on both Michigan’s rules and the destination state’s import requirements. As a general rule, the stricter of the two sets of requirements governs the shipment.

Key interstate movement requirements include:

• A Certificate of Veterinary Inspection (CVI), commonly called a health certificate, issued by a USDA-accredited veterinarian within a specified number of days before movement (typically 30 days)
• Official identification on all animals (USDA-approved ear tags or other approved ID)
• Negative brucellosis test results for sexually intact females over 6 months of age moving to certain states or under certain conditions
• Proof of official calfhood vaccination status for heifers, where applicable

Intrastate movement — moving animals within Michigan — is governed by MDARD rules under the Animal Industry Act. While intrastate movement generally carries fewer requirements than interstate shipment for Class Free states, Michigan still requires official identification on all cattle and bison, and any animal under quarantine may not be moved without explicit MDARD authorization.

Pro Tip: Always contact the destination state’s department of agriculture before shipping animals interstate. Requirements change, and the destination state’s rules may be more stringent than what Michigan requires at the point of origin.

Bison operations face an additional layer of complexity. Because bison are susceptible to brucellosis from wildlife contact — particularly in areas with known elk or deer reservoirs — some destination states impose stricter testing requirements on bison than on cattle, regardless of origin state status. Verify destination requirements specifically for bison before any interstate shipment.

The USDA APHIS cattle and bison health program page provides interstate movement requirement summaries and links to individual state import requirements, which is a practical starting point for planning any interstate shipment.

Michigan’s broader animal movement regulatory environment is also worth understanding in context. Just as dog leash laws vary significantly by jurisdiction — as illustrated in comparisons of Michigan dog leash laws and Ohio dog leash laws — livestock movement regulations differ meaningfully from state to state, making destination-specific verification essential.

Reporting and Quarantine Requirements in Michigan

Michigan law imposes mandatory reporting obligations on anyone who suspects or confirms a brucellosis infection in their herd. This is not a voluntary best practice — it is a legal requirement, and failure to report is itself a punishable offense under the Animal Industry Act.

If you observe clinical signs consistent with brucellosis — late-term abortions, retained placentas, weak calves, or sudden drops in milk production across multiple animals — you are required to notify MDARD or your USDA-accredited veterinarian immediately. Your veterinarian is also independently required to report any suspected brucellosis cases to MDARD and to the USDA APHIS Veterinary Services office.

Once a suspected case is reported, the following sequence of regulatory actions typically occurs:

1. Preliminary quarantine: MDARD places the affected premises under immediate quarantine, restricting all movement of cattle and bison onto or off the property pending investigation
2. Official investigation: State and federal veterinarians collect samples from all at-risk animals for official laboratory testing
3. Herd testing: If initial results are positive or inconclusive, the entire herd undergoes whole-herd testing
4. Quarantine maintenance: The quarantine remains in place until all animals test negative on two consecutive whole-herd tests conducted at the intervals specified by MDARD
5. Depopulation (if confirmed): In a confirmed positive herd, infected animals are subject to depopulation under state and federal authority, with indemnity payments available through the USDA APHIS program for qualifying animals

Important Note: A quarantine is not a punishment — it is a disease control measure. Cooperating fully and promptly with MDARD investigators is both legally required and in your best financial interest, as cooperation affects your eligibility for federal indemnity payments.

Michigan’s quarantine authority is broad. MDARD can quarantine individual animals, entire premises, or geographic zones if the epidemiological situation warrants it. During a quarantine, you may not sell, move, slaughter, or otherwise dispose of any quarantined animal without written MDARD authorization, even if the animal is not itself infected.

The reporting framework for brucellosis parallels the reporting structures used for other regulated animal conditions in Michigan. If you are also subject to Michigan beekeeping regulations or other agricultural compliance requirements, you will recognize the same pattern of mandatory reporting, official investigation, and movement restriction that characterizes the state’s approach to disease management across species.

Penalties for Brucellosis Violations in Michigan

Michigan’s Animal Industry Act provides MDARD with significant enforcement authority, and the penalties for brucellosis violations are substantial. Violations can result in civil fines, criminal charges, loss of operating privileges, and permanent damage to your herd’s marketability. Understanding the penalty structure is not about fear — it is about recognizing the seriousness with which Michigan treats disease control.

Under Act 466 of 1988, violations of brucellosis regulations can result in the following consequences:

• Civil penalties: MDARD may assess civil fines for violations including failure to test, failure to vaccinate when required, moving quarantined animals, and failure to report suspected cases. Fines can reach up to $5,000 per violation per day for continuing violations
• Criminal misdemeanor charges: Knowingly violating quarantine orders or falsifying health certificates or test records can result in misdemeanor criminal charges, with potential fines and imprisonment
• Criminal felony charges: In cases involving intentional fraud — such as falsifying official brucellosis test results or vaccination records to facilitate the illegal movement of animals — felony charges are possible under Michigan law
• Loss of indemnity eligibility: Producers who violate reporting requirements or quarantine orders may be disqualified from receiving federal indemnity payments for depopulated animals, compounding the financial impact significantly
• Market access restrictions: Animals from non-compliant operations may be refused at sale barns, slaughter facilities, and by receiving producers in other states, effectively cutting off your ability to market your herd

Common Mistake: Some producers attempt to move animals off a quarantined premises before official testing is complete, believing the animals are healthy. This is a serious violation regardless of the animal’s actual health status. The quarantine applies to the premises and all animals on it, not just to animals that have tested positive.

Federal penalties layer on top of state penalties in cases involving interstate movement violations. The USDA APHIS can pursue separate federal enforcement actions for violations of federal brucellosis regulations, particularly those involving falsified interstate health certificates or the illegal movement of animals known to be exposed to brucellosis.

If you are facing a potential compliance issue or have received a notice from MDARD, contacting a livestock attorney with experience in Michigan agricultural law is strongly advisable before responding. The intersection of state and federal authority in brucellosis enforcement creates a complex legal landscape where early professional guidance can significantly affect the outcome.

Staying informed about the full range of animal-related regulations in Michigan — from livestock disease laws to roadkill regulations and exotic animal ownership rules — helps you build the kind of comprehensive compliance awareness that protects your operation from unexpected liability.

Michigan’s brucellosis regulatory framework is thorough by design. The combination of classification monitoring, vaccination protocols, mandatory testing, strict movement controls, reporting obligations, and meaningful penalties reflects decades of hard-won progress in disease eradication. As a cattle or bison producer in Michigan, your compliance with these rules is not just a legal obligation — it is your contribution to keeping the state’s herds healthy and its Class Free status intact.