Canine Brucellosis Causes And Prevention

Canine brucellosis is a contagious bacterial infection produced by Gram-negative coccobacillus Brucella canis. The organism can infect cattle, sheep, goats, pigs, dogs, and humans. Cats, however, seem to be resistant to this pathogen. The bacteria are able to survive in macrophages by avoiding or suppressing host bactericidal mechanisms. The main sources of infection are vaginal fluids of infected females and urine in males. Although there are six pathogenic species of Brucella and most canine cases have been concerned with Brucella canis, dogs can become infected with Brucella abortus, Brucella melitensis and Brucella suis. Transmission of brucellosis from dogs to humans occurs, but it is quite rare. Close contact between people and infected dogs increases the risk of transmission. Although veterinarians exposed to blood of infected animals are at risk, pet owners are not considered to be at risk for infection. Although B. canis can infect humans, few cases are reported in humans or other animals, suggesting either host-preference for dogs or limited opportunities for transmission to other species.

The most significant signs are late abortions in females, inflammation of the testicles in males, infertility in both sexes, generalized inflammation of the lymph nodes, inflammation of the disk (discospondylitis), dermatitis, and uveitis. Other signs may include fever, hind limb weakness, lethargy, lameness, and lymph node swelling. In males, the primary sign of infection is inflammation of the testicles and reluctance to mate. Some infected animals may show no clinical signs, but still transmit the bacteria in semen or vaginal fluid.

The diagnosis is based on bacteriological examination and serological methods. Brucellosis is difficult to treat. It may take a long period of antibiotic therapy to fully rid the dog of the bacteria. Because of the persistent intracellular location of B. canis, no antibiotic treatment is 100% effective and the infection often recurs in animals that apparently have been treated successfully. Infected animals must be removed from the kennels and no longer used for breeding. Preferably, males should be castrated and females spayed. Repeated courses of antibacterial therapy are recommended.1

Brucellosis in dogs

Brucellosis is a serious, globally distributed zoonotic disease. Humans are susceptible to infection by Brucella suis, B. abortus, B. melitensis, and B. canis and can have lifelong symptoms of fever, enlarged lymph nodes, malaise, and arthritis People working in jobs requiring frequent contact with animals or meat, such as slaughterhouse workers, farmers, and veterinarians, are at high risk. The illness may be chronic and persist for years. Brucellosis is rare in the United States (except in the western states) and in visitors or immigrants from countries where it is prevalent (Spain, Mexico, South America, the Middle East). Since routine brucellosis diagnosis does not include B. canis investigation, infection with this species may be more widespread than is currently suspected. Humans become infected when they handle birth fluids or newborn puppies from infected bitches and fail to practice good hygienic practices. The disease in man is life-threatening with testicular swelling, recurrent fever and sometimes, disabling lesions of the spine. Immunocompromised persons (cancer patients, HIV-infected individuals, or transplantation patients) should not handle dogs known to be infected with B. canis. Depending on the timing of treatment and severity of illness, recovery may take a few weeks to several months. Do not consume unpasteurized milk, cheese, or ice cream while traveling. Do not feed your dog or puppies raw milk products. Hunters should use rubber gloves when handling internal organs of animals. There is no vaccine available for humans.

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Brucella suis Infection in Dogs

Brucellosis is a serious, globally distributed zoonotic disease. Humans are susceptible to infection by Brucella suis, B. abortus, B. melitensis, and B. canis and can have lifelong symptoms of undulating fever, enlarged lymph nodes, malaise, and arthritis. The United States was officially classified free of B. abortus. All states except Texas are classified as stage III (free) for swine brucellosis caused by Brucella suis. However, hunters and owners of hunting dogs are at high risk for transmission of brucellosis from wildlife. Occasional transmission of B. canis from pet dogs to their owners has been reported. There has been a recent increase in Brucella suis detection in dogs in southern Georgia, USA, and caution the public about the potential for transmission to humans in contact with infected dogs and wild hogs. Although transmission of Brucella suis from dogs to humans has not been reported, Brucella suis is second only to B. melitensis in its pathogenicity to humans. Therefore, dogs exposed to feral hogs should be tested for Brucella species. and monitored for clinical signs.4


  1. C. Greene. Infectious Diseases Of The Dog And Cat.
  2. Brucella suis Infection in Dogs, Georgia, USA
  3. Within-host evolution of Brucella canis during a canine brucellosis outbreak in a kennel. Miklós Gyuranecz1, Brandy D Rannals2, Christina A Allen, Szilárd Jánosi, Paul S Keim and Jeffrey T Foster
  4. Brucella suis Infection in Dogs, Georgia, USA

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