TB, Brucellosis, and Trichomoniasis Testing: Interstate Requirements by State

Why Disease Testing Is Required for Interstate Movement

The United States has spent decades and billions of dollars eradicating or controlling certain diseases in cattle. Tuberculosis, brucellosis, and trichomoniasis each represent a specific kind of risk: they can spread silently through a herd, they can be introduced to new areas through cattle movement, and they can be economically devastating if they take hold.

Disease testing before interstate movement is the primary mechanism states use to prevent re-introduction. By requiring a negative test before cattle enter, states create a filter that catches infected animals before they can expose new herds. The specific diseases tested for, and the conditions under which testing is required, vary by state based on each state's disease history, risk assessment, and regulatory approach.

For producers, the practical implication is this: the disease testing requirements for your movement depend on your destination state, and they can significantly affect your timeline. A TB test alone requires at least a 72-hour reading period, and lab-based tests for brucellosis may take several days. Planning ahead is essential.

Tuberculosis (TB) Testing

Bovine tuberculosis (caused by Mycobacterium bovis) is one of the oldest regulated cattle diseases in the United States. The federal-state cooperative TB eradication program has reduced prevalence to very low levels, but the disease has not been eliminated. Active TB zones exist in parts of Michigan and occasionally surface in other states.

Which States Require TB Testing?

Many states require a negative TB test for cattle entering from out of state. Some states exempt cattle from “TB-accredited-free” states, while others require testing regardless of origin. States with known TB issues (notably Michigan) often impose additional testing on outgoing cattle as well. The safest approach is to assume TB testing may be required and verify with the destination state.

Test Types

• Caudal Fold Tuberculin (CFT) test: The standard screening test. The vet injects tuberculin into the caudal fold (base of the tail) and reads the injection site 72 hours (plus or minus 6 hours) later. A positive or suspect result requires follow-up testing.
• Cervical Comparative test: A more specific follow-up test administered on the neck. Used to differentiate true TB positives from cross-reactions caused by other mycobacteria. This test also requires a 72-hour reading period.

Validity Periods

Most states accept TB test results for 60 days from the date of reading (not injection). Some states allow 90 days. A few states specify 30 days for cattle from higher-risk areas. Always count from the reading date, not the injection date.

Common Exemptions

• Cattle from TB-accredited-free states or herds (varies by destination state)
• Cattle going directly to slaughter at a federally inspected facility
• Cattle under a certain age (some states exempt calves under 2 months)
• Steers and spayed heifers (in some states)

Brucellosis Testing

Brucellosis (caused by Brucella abortus) was once one of the most devastating cattle diseases in the United States. After decades of federal and state eradication efforts, the disease has been nearly eliminated from the U.S. cattle herd. However, it persists in wild bison and elk populations in the Greater Yellowstone Area, and occasional spillover into domestic cattle keeps the testing infrastructure in place.

Which States Require Brucellosis Testing?

Brucellosis testing requirements depend heavily on the origin state's classification and the destination state's import policy. Most of the country is classified as “brucellosis class-free,” meaning the disease is not present in domestic herds. Cattle from class-free states moving to other class-free states often face reduced testing requirements. However, cattle from states with known brucellosis in wildlife (Idaho, Montana, Wyoming) may face additional scrutiny.

The Test

The standard brucellosis test is a blood draw (usually from the jugular or tail vein) for serological analysis. The test detects antibodies to Brucella abortus. Some approved serological tests, such as the Card test, can be performed by accredited veterinarians in the field with same-day results. Others require submission to a USDA-approved laboratory, with results typically available within a few days.

Validity Period

Brucellosis test results are typically valid for 30 days from the date of sample collection. This is a shorter window than TB tests, so timing is important when scheduling.

Common Exemptions

Brucellosis testing has more exemptions than any other disease test:

• Steers: Exempt in nearly all states (brucellosis is a reproductive disease)
• Spayed heifers: Exempt in most states
• Calves under 18 months: Exempt in most states (though some use different age thresholds)
• Cattle to slaughter: Exempt when moving directly to a federally inspected facility
• Cattle from class-free states: Many states waive testing for cattle from brucellosis-free classifications
• Official calfhood vaccinates: Some states reduce testing requirements for cattle that received the RB51 brucellosis vaccine as calves

Trichomoniasis Testing

Trichomoniasis (caused by Tritrichomonas foetus) is a sexually transmitted reproductive disease in cattle. It causes infertility, early embryonic death, and occasional abortions. The disease is transmitted by bulls during natural service breeding.

Who Gets Tested?

Trichomoniasis testing applies only to bulls. Cows are not tested for interstate movement purposes. The rationale is simple: bulls are the primary vector, and testing bulls is the most effective way to prevent spread.

Age Thresholds

States that require trich testing set an age threshold below which bulls are exempt. This reflects the fact that very young bulls are unlikely to be infected. Common thresholds include:

• 12 months: Used by several western and southern states
• 18 months: The most common threshold
• 24 months: Used by a few states

Some states also exempt “virgin bulls” — bulls that have never been exposed to females — with a signed statement from the owner or veterinarian.

The Test

The trich test involves collecting a preputial wash or scraping from the bull, which is submitted to a laboratory for culture or PCR analysis. The test typically requires the bull to have been sexually rested (no contact with females) for a period before sample collection, usually 2 weeks. Results take 5-7 days for culture-based tests, or 1-3 days for PCR.

Which States Require It?

Trich testing is most commonly required by western and southern states where natural service breeding is prevalent. States with large rangeland cattle operations tend to have trich requirements, while states dominated by dairy (where artificial insemination is standard) may not require it. However, if you are moving a bull interstate for breeding purposes, always check the destination state's requirements.

HPAI Pre-Movement Testing for Dairy Cattle

Following the 2024 detection of Highly Pathogenic Avian Influenza (HPAI) H5N1 in U.S. dairy herds, USDA APHIS issued Federal Orders requiring pre-movement testing of lactating dairy cattle before interstate movement. This requirement is in addition to the standard TB, brucellosis, and trichomoniasis testing described above.

What Is Required

Under USDA Federal Orders, lactating dairy cattle must test negative for influenza A virus before interstate movement. Testing methods have included bulk tank milk testing and individual animal testing, depending on the specific Federal Order in effect. The testing must be performed within a specified timeframe before movement, and negative results must be documented.

Requirements Change Rapidly

HPAI-related movement requirements have changed multiple times since the initial outbreak and may continue to evolve as the situation develops. Specific test protocols, timing requirements, and which classes of cattle are covered can change with short notice through updated Federal Orders. Always check the most current USDA APHIS Federal Orders and contact your state veterinarian's office before planning any interstate movement of dairy cattle.

Other Diseases That May Affect Interstate Movement

While TB, brucellosis, trichomoniasis, and HPAI are the most commonly encountered testing requirements, several other diseases can affect interstate cattle movement depending on the destination state and current disease conditions:

• Johne's disease (paratuberculosis): Some states have voluntary or mandatory Johne's disease programs that may affect import requirements. Cattle from herds enrolled in certain Johne's risk classification programs may face different entry conditions. Check the destination state's requirements.
• Anaplasmosis: Some southern and southwestern states may require anaplasmosis testing for cattle entering from certain regions, particularly during vector season. Requirements vary by state.
• Bovine Viral Diarrhea (BVD): Some states require testing for BVD persistent infection (PI) for certain classes of cattle, particularly young stock entering for feeding or breeding purposes. PI testing typically involves an ear notch sample.
• Vesicular stomatitis: During outbreak years, states may impose temporary movement restrictions and testing requirements on cattle originating from affected regions. These restrictions are typically lifted once the outbreak subsides.

Because these requirements vary significantly by state and can change based on current disease conditions, the safest approach is to always check the destination state's current import requirements before planning any movement.

How to Schedule Testing with Your Vet

Scheduling disease testing requires working backward from your intended movement date. Here is a practical timeline:

What to Do If a Test Comes Back Positive

A positive disease test is stressful, but there are clear protocols for each disease:

Positive TB Test

A positive CFT test does not automatically mean the animal has TB. False positives occur, particularly in cattle exposed to other mycobacteria or certain vaccines. The animal will be quarantined, and a cervical comparative test will be ordered for confirmation. If confirmed positive, the animal is condemned under federal regulations, and the herd may be placed under movement restrictions and whole-herd testing requirements. Your state veterinarian's office will guide you through the process.

Positive Brucellosis Test

Brucellosis is a federal program disease, so a positive test triggers USDA involvement. The animal is quarantined and confirmatory testing is performed. Because the U.S. is nearly brucellosis-free, a positive test often results from vaccination titers (RB51 or Strain 19 calfhood vaccine) rather than actual infection. Your vet and state animal health officials will work with you to determine the source. If confirmed, the herd faces quarantine, whole-herd testing, and potentially depopulation, though indemnity programs exist.

Positive Trich Test

A positive trich test in a bull means the animal is a carrier and will remain so for life — there is no effective treatment. The bull should not be used for natural service breeding. In most states, a trich-positive bull must be sent to slaughter or castrated. The remaining bulls in the herd should be tested, and any cows or heifers the positive bull bred should be monitored for pregnancy loss.

Frequently Asked Questions

References

• USDA APHIS — Bovine Tuberculosis
• USDA APHIS — Brucellosis
• 9 CFR Part 86 — Animal Disease Traceability
• Council on Dairy Cattle Breeding (CDCB)

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