Brucellosis in Dogs

Key takeaways

Brucella canis species of bacteria that primarily infects dogs. While it is the leading cause of reproductive disease in dogs world-wide, it is not common in pet dogs in North America.

  • Dogs primarily contract brucellosis during breeding
  • Many infected dogs show no symptoms or only mild signs like enlarged lymph nodes, but pregnant dogs may experience miscarriage
  • A blood sample is required to confirm diagnosis
  • B. canis can live in an infected animal for years and can cause long-term health issues
  • Humans are susceptible to many forms of brucellosis and cases of brucellosis must be reported to public health authorities
  • The prognosis is poor due to the risk to public health, the low success rate of treatment, and the economic impact of miscarriage to breeding kennels and agriculture
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A closer look: Brucellosis in Dogs

The average pet parent has little reason to be concerned about brucellosis.

While brucellosis is rare in pet dogs, it is a serious disease due to its potential to spread to humans, which is a public health concern. Brucellosis must always be reported to public health authorities, and the prognosis in dogs is poor.

Transmission to humans occurs, although the prevalence of human infections from canines is not known. Pregnant people, children, elderly people, and the immunocompromised are especially at risk.

Humans are most susceptible to Brucella melitensis infection, which prefers sheep and goat hosts. Brucella canis has low potential of transmission to humans compared to other Brucella species. However, B. canis is a notable zoonotic pathogen due to the close proximity shared by people and dogs.

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Risk factors

Brucellosis is uncommon in pet dogs in North America, but is the leading cause of reproductive disease in dogs world-wide. Breeding dogs, stray dogs, and dogs with access to livestock are more at risk.

Dogs that have come into contact with infected tissues and secretions are primarily infected via the oronasal route. Eye and genital mucosa are other potential routes of infection. Puppies have been known to be infected in-utero.

Brucella is most often transmitted during the mating process. Other dogs may be infected when they come into contact with infected livestock, contaminated raw milk, placentas, or aborted fetuses.

Male dogs with brucellosis may have testicular abnormalities and become infertile. Less commonly, brucellosis causes long-term eye, kidney, and skeletal issues in dogs, which vary in severity.

Brucellosis causes miscarriage in dogs (most often late in gestation). Puppies that survive gestation are less likely to survive once born.

Possible causes

Brucella is a gram-negative bacteria. There are many different species of Brucella, each with their preferred host animal. Brucella canis is the most common cause of canine brucellosis, although B. melitensis, B. abortus, and B. suis have also been known to cause brucellosis in canines.

Main symptoms

Most dogs infected with B. canis have no clinical signs.

Testing and diagnosis

If a screening blood test is positive, confirmatory testing must be done. Confirmed positive cases must be reported to local health authorities immediately.

Steps to Recovery

Antibiotics do not completely eliminate the B. canis bacteria from an infected animal. Treatment in dogs is not recommended due to the high risk of relapse and the risk to public health. Unfortunately, most dogs diagnosed with brucellosis are euthanized. In some states, euthanasia is mandatory.

The prognosis for dogs with brucellosis is poor because dogs are typically euthanized due to high risk to public health.

If treatment is attempted, there is a high risk of relapse. Dogs undergoing attempted treatment require multiple rounds of antibiotics, usually with little success. Spaying or neutering infected dogs helps reduce risk of transmission via breeding.


There is currently no vaccine for canine brucellosis. Prevention centers around early testing of breeding dogs, eliminating infected dogs, and disinfecting potentially contaminated materials. Brucella organisms can survive in the environment for months under the right conditions, but bleach is highly effective for destroying them.

Is Brucellosis in Dogs common?

Dogs are the definitive hosts of Brucella canis, but infection is not common in pet dogs in North America. Some countries have higher rates of B. canis than others, and dogs that have not been spayed or neutered are more commonly infected.

Typical Treatment

  • Antibiotics
  • Euthanasia
  • Reporting to public health authorities