Canine Brucellosis

​​​Disease Basics

Brucellosis is a contagious disease caused by the Brucella bacteria. This bacterium primarily affects the reproductive organs of male and female dogs. Brucellosis can cause infertility and late abortions in female dogs. In male dogs, it can cause testicular or scrotal inflammation and infertility. This disease can also cause puppies to be stillborn or very weak at birth.

​Brucellosis can infect dogs of any breed and any age, though it is most common in mature dogs. It is transmitted by contact with infected fluids, especially during breeding or birth, and is a zoonotic disease, which means it can be transmitted to humans. 


Canine brucellosis is mainly transmitted by nose and mouth contact with vaginal discharge from an infected female.  It can also be transmitted through semen or urine and can be shed by intact or neutered males for several years in cases of chronic infection. Therefore, the best way to prevent the transmission of brucellosis is to minimize exposure.  Keep healthy dogs away from known infected dogs. Before breeding, both the male and female dog should be examined by a veterinarian and tested for the disease.  Dogs should not be bred if they test positive for brucellosis.  Reducing the risk of exposing dogs also reduces human risk. 

​Clinical Signs of Illness

If a dog has brucellosis, he or she will probably exhibit some of the following signs:

  • Lethargy
  • Swollen lymph nodes
  • Difficulty walking
  • Back pain
  • Weak, sickly newborn puppies
  • Vaginal discharge
  • Swollen testicles
  • Inflammation of the skin around the scrotum


Brucellosis can be a difficult disease to diagnose.  A veterinarian may recommend several tests to confirm the diagnosis.

If a dog has been diagnosed with brucellosis, the veterinarian will most likely recommend spaying or neutering to prevent the transmission of the disease to other dogs. Additionally, a combination of antibiotics will likely be recommended to treat the dog. Follow up testing for brucellosis is recommended to assess if treatment is successful.

​Human Health

Brucella bacteria can infect humans, but the severity of the infection can vary and is difficult to diagnose in people. Those who work in close contact with dogs, such as kennel operators, dog breeders or those in research or diagnostic laboratories, are considered to be most at risk for B. canis infection. However, people with immune compromise due to illness or immunosuppressive therapy and children or pregnant women are vulnerable to brucellosis.