Brucellosis Laws in California: What Livestock Owners Need to Know

Brucellosis is one of the most closely monitored livestock diseases in the United States, and California has built a detailed regulatory framework to keep it that way. Whether you raise dairy cattle, beef cattle, bison, or other susceptible species, understanding California’s brucellosis rules is not optional — it is a legal obligation that carries real consequences if ignored.

California has maintained a brucellosis-free classification since 1997, a status the state actively works to protect through vaccination mandates, surveillance testing, strict movement controls, and mandatory reporting. This guide walks you through every layer of those requirements so you know exactly what the law demands of you as a livestock owner or handler in the state.

What Is Brucellosis and Why It Is Regulated in California

Brucellosis, also known as contagious abortion or Bang’s disease, is a contagious disease of livestock that also affects humans. In humans, it is known as undulant fever because of the intermittent fever that may accompany infection.

The disease is caused by a group of bacteria of the genus Brucella. Within this group, several species are of concern in livestock: Brucella suis, which predominantly affects swine and reindeer but can also affect cattle and bison; Brucella melitensis, the most important species in small ruminants and not present in the U.S. but common in Mexico; Brucella ovis, which affects sheep and can cause infertility in rams; and Brucella abortus, the most common cause of brucellosis and the primary concern for cattle.

In cattle, the disease usually localizes in the reproductive organs and the udder. Bacteria are shed in milk or leave the body with the aborted fetus, placenta, or with any discharges from the reproductive tract of an infected animal. Brucellosis is commonly transmitted by direct contact but can also be transmitted to animals that come into contact with a contaminated environment.

It is one of the most serious diseases of livestock due to its ability to spread rapidly and cause significant reproductive losses in animals, and its zoonotic potential. That zoonotic risk — the ability to infect humans — is a key reason California law treats this disease with particular seriousness.

Primary sources of human infection are occupational exposure (farmers, ranchers, veterinarians, and packing plant workers) and consumption of imported unpasteurized dairy products; people may also become infected during travel to countries where the disease is more prevalent. There is no danger from eating cooked meat or properly pasteurized dairy products because normal cooking temperatures kill the disease-causing bacteria.

A national eradication program has left most of the U.S. free of bovine brucellosis; however, a reservoir remains in the Greater Yellowstone Area, particularly in elk and bison, and spillover transmission does occur to domestic cattle herds. This ongoing wildlife reservoir is the primary reason California continues to enforce active vaccination and surveillance requirements even decades after achieving free status.

California’s Brucellosis Classification Status

California has been brucellosis free since 1997. That designation carries significant regulatory and economic weight, and the state works in coordination with federal authorities to maintain it.

Under federal regulations, California holds Class Free status — the highest classification available under the USDA’s brucellosis area designation system. The classifications run from Class Free down through Class A, Class B, and Class C, with restrictions on moving cattle and bison interstate becoming less stringent as a state approaches or achieves Class Free status.

States are designated brucellosis free when no cattle or bison are found to be infected for 12 consecutive months. Requirements for Class Free status include that the cattle and/or bison herds in the state or area within the state must have remained free from infections with field strains of Brucella abortus for at least 12 months.

California has been classified free of bovine brucellosis since 1997 and, according to a report from the USDA-APHIS, all the United States are now free of brucellosis in cattle. Despite this national achievement, introducing brucellosis into California with cattle imported from the Greater Yellowstone Area remains a concern, and California maintains a brucellosis vaccination program, despite its high cost, to prevent the severe consequences of introduction of the disease from other states through movement of cattle.

California’s brucellosis-free classification also extends to swine. California is involved in the National Swine Brucellosis Eradication Program and was declared a Certified Free (Stage 3) state in 1980. However, in some areas of California, B. suis is established in feral pig populations, making it important to maintain separation of domestic and feral swine.

For a comparison of how other states manage their brucellosis classifications and obligations, see the rules in place for brucellosis laws in Michigan and brucellosis laws in Minnesota.

Vaccination Requirements in California

California’s vaccination rules differ significantly depending on whether you own dairy breed or beef breed cattle. The rules were updated as of October 2021, so it is important to understand what changed and what remains in effect.

Dairy Breed Heifers

All female dairy calves shall be vaccinated against brucellosis with an approved Brucella vaccine between the ages of four through 12 months (120 through 365 days). The brucellosis vaccination requirement for dairy breed heifers four months of age and older remains and is still in effect. This requirement applies whether the animals are moving within California or entering from another state.

Beef Breed Heifers

As of October 1, 2021, California no longer requires brucellosis vaccination for beef breed heifers entering or moving within the state. However, the removal of the vaccination mandate does not eliminate all obligations. Beef breed heifers six months of age and older entering California are still required to have official identification.

Female beef calves, if vaccinated against brucellosis, shall be vaccinated between the ages of four through 12 months (120 through 365 days). In other words, if you choose to vaccinate beef heifers voluntarily, you must still follow the state’s age and procedural requirements.

Vaccine Identification and Reporting

All calves vaccinated pursuant to this section shall be identified in compliance with the relevant sections of the California Code of Regulations. The use of all vaccines for brucellosis calfhood vaccination and eartags used for identification shall be reported to the Animal Health Branch within 14 calendar days.

Veterinarians may use the Report of Heifer Calves Vaccinated — Brucellosis, AHB Form 76-026, as provided by the Department, or another form or method to report heifer calves vaccinated for brucellosis, which at minimum must contain the required information.

Adult Vaccination

A female bovine animal over the eligible age prescribed for calfhood vaccination may be vaccinated with an approved adult brucellosis vaccine as part of an individual whole-herd vaccination plan as agreed to by the Department and the owner of that herd. Adult vaccination shall be supervised by a state or federal veterinarian. Each animal vaccinated under this plan shall be negative to an official blood test for brucellosis before vaccination and shall be permanently identified in accordance with the agreement developed as part of the whole-herd vaccination plan.

Contract veterinarians administering brucellosis vaccines must be state-licensed and hold USDA Category II accreditation. The vaccination contract shall be valid for up to two years. The Department may suspend temporarily or cancel the contract of a veterinarian not complying with any part of the contract.

Testing Requirements for Cattle and Bison in California

California uses multiple surveillance methods to detect brucellosis infection in cattle and bison. Understanding which tests apply to your operation helps you stay compliant and avoid unexpected delays during sales or transfers.

Three Primary Surveillance Methods

Three surveillance procedures are used to detect infection in cattle: the Market Cattle Identification (MCI) program blood samples at slaughter, the Brucellosis Ring Test (BRT) performed on milk samples, and brucellosis blood testing done on animals for movement or change of ownership by private practitioners.

• Market Cattle Identification (MCI) Program: The primary surveillance method is a blood test from a sample of cattle more than two years old at slaughter. Numbered tags or backtags are placed on the shoulders of all cattle being marketed, and blood samples are collected at packing plants according to the National Brucellosis Surveillance Plan.
• Brucellosis Ring Test (BRT): This milk-based test is used on dairy herds and provides a cost-effective herd-level screening tool without requiring individual blood draws.
• Individual Blood Testing: The final surveillance method is a blood sample taken from a live animal by an accredited veterinarian for the purpose of private sales, change of ownership, interstate movement, herd certification, or show, at the expense of the owner.

Laboratory Requirements

Brucellosis testing must be done at a CDFA or USDA approved laboratory. You cannot submit samples to just any diagnostic lab — the facility must carry official approval from either the California Department of Food and Agriculture or the USDA’s Animal and Plant Health Inspection Service (APHIS).

Herd Investigation Procedures

If a sample reacts to the test, it is traced by the backtag number to the owner of the herd from which the animal originated. The owner is contacted by a state or federal animal health official to arrange for an investigation that may involve testing the entire herd.

The incubation period in cattle is quite variable, with abortions and stillbirths occurring two weeks to five months after infection. Cattle may be infected as calves but not show any signs of infection until they abort. Infected animals usually develop a positive reaction to the test within 30 to 60 days after infection, although some may not develop a positive reaction for several months. This variability is why surveillance testing at multiple points in an animal’s life cycle is so important.

Interstate and Intrastate Movement Rules in California

California’s movement rules for brucellosis-susceptible animals are among the most detailed in the state’s livestock regulatory framework. The rules differ based on breed, direction of movement, and destination.

Intrastate Movement of Dairy Cattle

No person shall move, or cause to be moved, from one location to another within California, or receive, or cause to be received, any female cattle of the dairy breeds unless they bear evidence of official brucellosis vaccination by the presence of a legible official brucellosis tattoo.

There are specific exemptions to this intrastate vaccination requirement. Cattle moving directly to a recognized slaughtering establishment where they are slaughtered within three calendar days of arrival are exempt, as are cattle moving only for pasture or grazing purposes to premises under the control of the owner and returning to the premises of their origin, provided there has been no commingling with other cattle. Additional exemptions cover cattle not vaccinated against brucellosis moving with a special entry or other written permit, and cattle moving directly into a registered feedlot for feeding.

Interstate Movement into California

As of October 1, 2021, California no longer requires brucellosis vaccination for beef breed heifers entering or moving within the state. However, beef breed heifers six months of age and older entering California are still required to have official identification.

For sexually intact cervids entering California, separate rules apply. Sexually intact cervids six months of age or older shall be tested for brucellosis within 30 days prior to entry into California utilizing an official brucellosis laboratory test for Cervidae as determined by USDA. However, cervids originating from Certified Brucellosis-Free cervid herds do not require testing for importation.

Critical Brucellosis Areas

California law provides a mechanism for designating specific counties or regions as Critical Brucellosis Areas when elevated risk is identified. The county, counties, or area shall be declared a Critical Brucellosis Area by the Department. Female cattle may enter a Critical Brucellosis Area from within the state only if they bear evidence of official calfhood vaccination against brucellosis.

No person shall move, or cause to be moved, any cattle from a premises in a Critical Brucellosis Area to another premises, either within or outside of a Critical Brucellosis Area, or receive any cattle from a premises in a Critical Brucellosis Area unless they are accompanied by evidence of an official negative blood test for brucellosis conducted within 30 calendar days prior to the movement.

In cases of demonstrated hardship or of an emergency beyond the control of the cattle owner, the Department may issue a conditional permit allowing the movement of cattle from one location to another.

For a comparison of how neighboring states handle similar movement controls, review the regulations covering brucellosis laws in Nevada and brucellosis laws in Nebraska.

Reporting and Quarantine Requirements in California

If you suspect or confirm brucellosis in your herd, California law imposes immediate obligations. Delayed reporting or failure to cooperate with quarantine procedures can escalate a manageable situation into a serious legal matter.

Reporting Structure

California’s Food and Agricultural Code, Division 5, Part 1, Chapter 1 establishes the reporting framework for diseased animals and poultry under Article 1 (Sections 9101 et seq.). Any livestock owner, veterinarian, or handler who suspects brucellosis infection is expected to notify the CDFA’s Animal Health Branch promptly. The CDFA Animal Health Branch can be reached at 916-900-5002 or via email at ahbfeedback@cdfa.ca.gov.

There is a cooperative State-Federal brucellosis eradication program to eliminate the disease from the U.S. livestock population, and the success of the program depends on the participation of livestock producers. That participation begins with timely, accurate reporting when disease is suspected.

Quarantine and Herd Depopulation

Disease control and eradication measures include quarantines to stop the movement of possibly infected or exposed animals, testing and examination to detect infection, destruction of infected — and sometimes exposed — animals to prevent further disease spread, treatment to eliminate parasites, vaccination in some cases, and cleaning and disinfection of contaminated premises.

When a herd is confirmed as brucellosis-affected, the CDFA has authority to impose a full quarantine on the premises. Animals under quarantine may not be moved without written departmental authorization. Regulations provide that a Class Free state or area may have no more than one herd determined to be affected with brucellosis within a two-year period, and if a herd is found to be affected, it is required to be depopulated within 60 days of an infected animal being detected.

Compensation for Depopulated Herds

California law addresses compensation for owners whose herds must be depopulated as part of eradication efforts. However, compensation is contingent on owner cooperation. If an owner of a brucellosis-infected herd fails to cooperate with the department’s eradication efforts, the cattle owner shall immediately become responsible for paying to the director all further costs incurred by the department in eradicating the disease from the herd.

If you own or manage livestock in California beyond cattle, you should also be familiar with the broader animal law landscape. Related California-specific regulations are covered in guides on goat ownership laws in California and backyard pig laws in California.

Penalties for Brucellosis Violations in California

California enforces its brucellosis regulations through a layered penalty system that includes civil fines, misdemeanor charges, and cost recovery provisions. The severity of the consequence depends on the nature of the violation and whether it was willful or the result of negligence.

Criminal Penalties

If any owner or person in charge of cattle, after 10 days’ written notice by the department, refuses to properly confine in corrals, stanchions, or chutes any cattle within a brucellosis control area that are required to be tested and identified pursuant to California law, the owner is guilty of a misdemeanor and the department may incur such expense as is necessary to properly confine and identify the cattle.

Misdemeanor liability can also arise from moving quarantined animals without authorization, falsifying vaccination or testing records, or obstructing a state or federal animal health investigation.

Civil Penalties

Violations of quarantine measures can result in fines of up to $25,000, particularly if the offense leads to the spread of a regulated pest or disease. Failure to comply with California’s agricultural laws can result in fines, license revocations, and criminal charges.

The California Food and Agricultural Code establishes a tiered violation classification system. Violation classes are designated as serious, moderate, and minor to establish maximum penalty amounts, and repeat violations may result in an escalation of violation class and/or penalty. Escalation of penalties may apply for a revolving five-year period from the date of each unique section code violation.

Cost Recovery

Beyond fines and criminal exposure, California can pursue cost recovery against non-compliant owners. If the state must step in to confine, test, or depopulate animals because an owner refused to act, the owner bears the financial responsibility for those government-incurred costs. This cost recovery mechanism can far exceed the face value of any civil fine, particularly for large herds.

Injunctive Relief

Upon a complaint by the director, the Attorney General may bring an action for civil penalties in any court of competent jurisdiction against any person violating the relevant division or any regulation adopted pursuant to it. Upon the failure of any person to comply, the Attorney General, upon request of the director, or the county counsel upon request of the commissioner, shall petition the superior court for the issuance of a preliminary or permanent injunction restraining the person from continuing any activities in violation.

For context on how California’s broader animal ownership laws intersect with disease regulations, you may also find it useful to review pet laws in California and the regulations covered in backyard chicken laws in California. For a state-by-state comparison, the brucellosis laws in Missouri guide provides a useful reference point.

Conclusion

California’s brucellosis regulatory framework is one of the most thorough in the country — and for good reason. Maintaining Class Free status since 1997 has required consistent enforcement of vaccination mandates, rigorous surveillance testing, strict movement controls, and a well-defined reporting and quarantine system. As a livestock owner or handler in California, your compliance with these rules is not just a legal formality; it is an active contribution to protecting animal health, public health, and the state’s agricultural economy.

The core obligations to keep in mind are straightforward: vaccinate all dairy breed heifers on schedule, ensure proper identification for all cattle entering the state, use only CDFA- or USDA-approved laboratories for testing, report any suspected infections immediately, and never move animals under quarantine without written departmental approval. Staying current with CDFA guidance — particularly as vaccine pricing and specific requirements are updated — will help you remain compliant and avoid the escalating penalties that come with violations.

If you manage livestock across multiple states or have questions about how California’s rules interact with those of neighboring jurisdictions, consult a licensed veterinarian with USDA Category II accreditation or contact the CDFA Animal Health Branch directly at 916-900-5002 for guidance specific to your operation.