Canine Brucellosis Testing: When to Test, Retest and Confirm Results

What is canine brucellosis?

Canine brucellosis is an infectious disease most commonly associated with the bacterium Brucella canis. It can affect dogs of any sex or age, although reproductive abnormalities are among its best-known clinical presentations.

Infected dogs may show infertility, abortion, stillbirth, weak puppies, testicular inflammation, epididymitis or reproductive discharge. Other dogs may have less specific signs, such as lethargy, enlarged lymph nodes, back pain or lameness. Some infected dogs may appear clinically healthy.

Because clinical signs are variable and may be absent, laboratory testing plays an important role in identifying dogs that may have been exposed. Cornell University's College of Veterinary Medicine notes that false-negative serological results can occur during early infection, particularly before a sufficient antibody response has developed.

For a simpler introduction to transmission and clinical signs, read Brucellosis in Dogs: Symptoms, Transmission and Screening .

When should a dog be tested for brucellosis?

Testing decisions should be based on the dog's history, potential exposure, intended use and applicable veterinary or regulatory requirements. Situations in which testing may be appropriate include:

• Before mating or entering a breeding programme
• Before introducing a new dog into a breeding kennel
• Following abortion, stillbirth, infertility or weak neonatal puppies
• When epididymitis, orchitis or other reproductive abnormalities are observed
• After known or suspected contact with an infected dog
• After exposure to reproductive fluids, aborted material or contaminated equipment
• Before or after international movement when required by the destination country
• When investigating infection within a shelter, kennel or multi-dog household
• When recommended by a veterinarian or public animal-health authority

Screening dogs before breeding is particularly important because an apparently healthy animal may still introduce infection into a kennel. Testing requirements and recommended intervals vary by country, region, breeding organisation and animal-health authority.

How soon after exposure can canine brucellosis be detected?

The ideal testing window depends on the diagnostic method being used and the stage of infection. Antibody-based tests depend on the dog developing a detectable immune response. A blood sample collected very soon after exposure may therefore test negative even though infection is developing.

Cornell University reports that false-negative results may occur during the first weeks of acute infection when antibody concentrations remain too low for reliable detection. Consequently, a single early negative antibody test does not always exclude recent infection.

Antibiotic administration may also affect certain diagnostic approaches, particularly bacterial culture. The testing laboratory should be informed about recent or current treatment before samples are collected or submitted.

Which tests are used for canine brucellosis?

No single testing method is ideal in every situation. The most appropriate approach depends on whether the objective is rapid screening, clinical diagnosis, confirmation, surveillance or certification for animal movement.

Rapid Brucella antibody tests

A canine Brucella antibody rapid test is designed to provide a qualitative screening result from an accepted specimen type. Rapid formats can help veterinarians, breeders and animal-health professionals identify dogs that should be referred for further assessment.

The AffiVET® Canine Brucella Antibody Rapid Test Kit is intended for antibody detection using canine whole blood, serum or plasma. The instructions for use, specimen requirements, reading time, storage conditions and interpretation criteria should be reviewed before testing.

Rapid screening should not be treated as a substitute for a complete veterinary diagnosis. Clinical findings, exposure history and confirmatory laboratory testing may all be required.

Laboratory serology

Veterinary diagnostic laboratories may use agglutination, agar gel immunodiffusion, immunofluorescence or multiplex antibody methods. Some laboratories combine several serological approaches to improve diagnostic confidence and investigate non-negative screening results.

PCR and bacterial culture

PCR detects bacterial genetic material, while culture attempts to isolate viable organisms. The probability of detection can depend on the sample, timing, tissue distribution and intermittent bacterial shedding.

Culture and handling of suspected Brucella material require appropriate laboratory biosafety procedures. Suspected samples should be clearly identified before submission so the receiving laboratory can apply the necessary precautions.

How should canine Brucella test results be interpreted?

A test result should always be interpreted within the complete clinical and epidemiological context. The result alone does not provide information about the exact date of infection, the degree of bacterial shedding or the risk associated with every future contact.

What does a negative rapid test mean?

A valid negative result means antibodies were not detected by that test at the time of sampling. It does not necessarily exclude very recent exposure, a weak or variable immune response, specimen problems or other method-specific limitations.

When exposure is recent or clinical suspicion remains high, retesting or laboratory investigation may still be appropriate.

What does a reactive rapid test mean?

A reactive screening result indicates that antibodies were detected and that the dog requires further evaluation. The dog should not automatically be considered definitively infected solely on the basis of an initial rapid screening result.

A veterinarian may recommend testing a new sample with one or more laboratory methods. Temporary measures to limit contact with other dogs may also be appropriate while confirmation is pending.

What does an invalid result mean?

An invalid result means the test did not perform as expected. The result should not be interpreted as positive or negative. The procedure should be repeated with a new test device and, when appropriate, a newly collected specimen.

When should a dog be retested for Brucella canis?

Retesting may be recommended when the initial sample was collected soon after a suspected exposure, when clinical suspicion remains despite a negative result, or when an animal-health protocol requires serial testing.

Common reasons for repeat testing include:

• The initial test occurred during the early post-exposure period
• The dog continues to show reproductive or systemic abnormalities
• A kennel contact subsequently receives a positive or suspect result
• The first screening result was reactive and confirmation is required
• The first result was invalid or specimen quality was uncertain
• A breeder, laboratory, authority or importing country requires another sample
• Serial monitoring is being performed after a confirmed diagnosis

There is no universal retesting interval suitable for every dog. The veterinarian or competent authority should determine the interval based on the probable exposure date, diagnostic method and purpose of testing.

Canine brucellosis testing for breeding dogs and kennels

Breeding facilities require a preventive testing strategy rather than a response limited to visibly sick dogs. Both male and female dogs can be affected, and clinically normal animals may contribute to transmission.

A practical kennel programme may include:

• Testing dogs before mating
• Testing new dogs before entry into the resident breeding population
• Maintaining separation while results are pending
• Recording specimen dates, methods, results and laboratory details
• Using dedicated or properly disinfected reproductive equipment
• Applying appropriate precautions around births, abortions and reproductive discharge
• Investigating reproductive failure rather than repeatedly breeding without diagnosis
• Following veterinary guidance when a dog has a reactive or confirmed result

Testing imported dogs and dogs travelling internationally

Canine brucellosis requirements are increasingly relevant to international dog movement. Rules can differ according to the origin, destination, reproductive status, type of movement and wording of the applicable health certificate.

For example, the United Kingdom provides specific government information for veterinary professionals concerning B. canis testing and reporting. Australia's Department of Agriculture also specifies accepted testing conditions for certain dog imports, including the timing of blood collection before export.

These requirements can change. Dog owners, exporters and veterinarians should always consult the current official import conditions rather than relying on an old certificate, a previous shipment or a general internet summary.

What should happen after a reactive canine Brucella result?

A reactive result should be managed carefully because of the potential implications for other dogs, breeding activity, kennel personnel and public health.

1. Contact a veterinarian. Provide the test result, test method, sampling date and relevant exposure or reproductive history.
2. Temporarily restrict breeding and close-contact activities. Avoid mating, semen collection and unnecessary movement while the result is being investigated.
3. Separate the dog when advised. Reduce potential exposure of other dogs to reproductive fluids, urine, blood and contaminated materials.
4. Arrange confirmatory testing. The veterinarian may communicate with a specialist veterinary diagnostic laboratory about the correct sample and test combination.
5. Review other potentially exposed dogs. Kennel mates, breeding partners and dogs exposed to reproductive material may also require assessment.
6. Check reporting obligations. Canine brucellosis may be reportable or notifiable in certain jurisdictions.

People who believe they have had significant exposure to infected canine reproductive material, blood or other high-risk fluids should contact an appropriate healthcare or public-health professional.

Frequently asked questions about canine brucellosis testing