Advice for pet owners

Brucella canis: what animal owners need to know

Brucella canis is a bacterium which causes canine brucellosis, an infectious disease which mainly affects dogs, but can also infect humans. 

The UK was previously considered free of B. canis, but in recent years there has been a significant increase in the number of cases reported. In 2022, news emerged of the first UK case of dog-to-human transmission, highlighting the risks to those handling infected dogs. As awareness and concern has risen, testing for the infection has become more common in UK veterinary practices.

B. canis should not be confused with other Brucella species, such as B. abortus, B. melitensis and B. suis, which infect livestock and account for the vast majority of human infections globally.

This resource covers some of the top questions we’ve heard from animal owners about the disease and testing requirements.

The most common routes of transmission between infected dogs are:

  • through mating
  • through contact with products associated with abortion and birth from an infected bitch, eg amniotic fluid, placentae, vaginal discharges
  • from mother to pup within the uterus or via their milk
  • through contact with infectious seminal fluid
  • to a lesser extent, through contact with infectious urine, faeces, saliva, tears or nasal secretions

Many infected dogs will not show any signs of disease, meaning they can carry and spread the infection without anyone knowing. For others, it can cause a wide range of clinical signs, including abortion in pregnant bitches, puppies being very weak and dying shortly after birth, infertility, lameness, muscle weakness and spinal pain, and less-specific signs such as lethargy and weight loss.

The most recent HAIRs risk assessment states that the risk to humans is very low. Further research into the impact on humans is needed to fully understand this disease, but its impacts are generally less severe than those caused by other Brucella species, and there have been no documented reports of fatalities. 

The greatest risk of contracting B. canis comes from contact with products associated with whelping or abortion. Anecdotally, attempting ‘mouth-to-snout’ resuscitation of newborn puppies is a feature common to several human cases.

Due to the nature of their work, veterinarians and laboratory technicians may face additional significant risks, eg through contact with infectious tissue and cultured blood.

Antibiotics are used to treat humans, but the symptoms are often associated with other illnesses and may go untreated. The most common signs of infection in humans include fever, sometimes accompanied by loss of appetite, weight loss, sweating, headaches, fatigue, back and/or joint pain. If left untreated, the disease can lead to severe illness and complications such as endocarditis, osteomyelitis, arthritis, meningitis and septicaemia. It can take months or years before any symptoms develop.

Anyone concerned about potential exposure should contact their GP and alert them of their possible exposure to a dog with B. canis specifically.

Veterinary teams need to keep themselves and their team members safe, as well as the other animals they treat in practice. As the number of cases reported has been increasing and we are now more aware of the risks, many veterinary practices now require B. canis tests for some dogs before treating them.

The most common group of dogs being tested are those they have previously been imported from another country. This is because the disease is much more prevalent in some countries, including parts of Europe where many dogs travel from, and so the chances of them being infected are higher.

As dogs may not show any symptoms of infection, those that have been in the UK for some time are still at risk and could spread the disease. Even if your dog has been in the UK for many years, it is advisable to test for B. canis for peace of mind, or to enable you to take steps to protect yourself and others if they are infected.

If you’re planning to import a dog from overseas, we recommend testing for B. canis before they travel to the UK. B. canis is not currently very common in the UK, and we’d like to keep it that way. We’re now calling on the Government to introduce mandatory pre-import testing for dogs travelling to the UK from countries with diseases not commonly found here, like B. canis, as this will help to keep people and their pets safe.

Note that some vets may refuse to treat a dog which has been imported until a test has been carried out. Whilst vets still have a duty of care to animal welfare (eg in an emergency), they are not expected to compromise their personal safety when attending to animals and are legally entitled to put such measures in place. Animal owners are advised to discuss options with their veterinary team if they do not wish to carry out a test.

A range of tests are available for B. canis. As with any tests, none can be 100% accurate, with false positives or negatives possible, so a combination of tests may be used to improve reliability of the result. Your veterinary team should discuss the process and potential outcomes with you prior to testing. Note that all vets have a legal duty to report positive tests to the appropriate authorities, and will recommend precautions to prevent spread of B. canis. In Northern Ireland, vets also have a responsibility to report any suspicion of the disease.

If your dog tests positive for B. canis, your vet will need to take other factors into account, eg clinical signs of disease, when deciding on the best course of action. If a dog unexpectedly tests positive (eg has no clinical signs), you may be asked to keep the dog isolated and repeat the testing after a few weeks.

There is no proven, reliable treatment that fully eliminates the infection, so euthanasia is currently the only known means of completely preventing transmission. If your dog tests positive for B. canis, it’s likely your vet will recommend this as an option to protect you, other dogs and humans from the possible spread of disease. However, this is not a legal requirement, so you can discuss other options with them, which may include:

  • Isolation: due to risk of onward transmission, infected dogs should have limited to no direct or indirect contact with other dogs and limited contact with people, particularly, the young, old, pregnant, or otherwise immunocompromised individuals.
  • Neutering: surgically neutering dogs can help to limit bacterial shedding and risk of relapse.
  • Antimicrobials: an extended course of antibiotics may help to fight the infection, though relapse is possible when treatment stops. The potential for side effects and impact on antimicrobial resistance must be considered.
  • Monitoring: regular testing monitoring following diagnosis and treatment should be considered indefinitely to identify and manage relapses.
  • Lifestyle management: infected dogs should not be used for breeding, and non-reproductive means of transmission must be considered, eg via excretion of infected urine, contact with other dogs, ingestion, inhalation, contact with mucous membranes (such as the eyes), and through broken skin (eg cuts and grazes).

When discussing treatment options, it's important that the impact on the infected dog’s health and welfare is considered, as well as antimicrobial stewardship implications and financial costs. Animal owners may find it useful to read the UK Health Security Agency’s Guidance when making their decisions.

The possible risk to other dogs and humans, and the willingness of veterinary practitioners to see and treat dogs with B. canis, will also have an impact on the owners’ decision. Together, these issues can often mean that euthanasia is the best option for the dog’s welfare, and to protect others, but owners should consult with their vet before making this challenging decision.

The risk to the general public is currently deemed to be very low, so for most people there is no need to take action. However, if you are planning to import a dog from overseas, make sure they are tested for B. canis before entering the country, and do not bring them to the UK if infected. It is important that we reduce the risks of B. canis entering the UK as much as possible, to protect all dogs and people living here.

If you have already imported a dog from abroad and have not already tested for B. canis, talk to your vet about getting a test to bring peace of mind or enable you to decide on measures which protect yourself and others.

One of the most common ways for B. canis to spread between dogs is during mating, so if you are going to breed your dog, consider asking for proof of a negative test from all animals involved.

If you discover you have been in contact with a dog that has tested positive for B. canis and you have symptoms associated with the disease, talk to your GP and let them know about your concerns.

More information

More information can be found in the UK Health Security Agency’s Brucella canis: information for the public and dog owners

Veterinary teams and policy makers should check out our Brucella canis webpage.