Brucellosis

Brucellosis is a disease that affects dogs, caused by the organism Brucella canis. This is of primary concern in breeding animals because of the organism’s ability to cause abortions and infertility. Some cases of mild human infection have been reported.

This is a disease most commonly seen in sexually mature dogs. Signs of infection include lethargy, loss of libido (sexual drive), and swollen lymph nodes (glands). Infections localizing in the spine will produce back pain. However, some dogs may appear outwardly healthy. Pregnant bitches will abort especially late in pregnancy with still births and early embryonic death also reported. Failure to become pregnant may be a result of either male or female infertility. In males the scrotal sacs swell, dermatitis develops over the scrotum, testicular atrophy (decrease in testicle size) may occur and the epididymus (storage tubules for sperm) becomes firm and enlarged. Abnormal sperm will be observed from 5 weeks post infection with the majority of sperm becoming abnormal by 20 weeks. Dogs with chronic infections sometimes have spinal pain, posterior (back end) weakness, ataxia (incoordination) and anterior uveitis.

Often the combination of symptoms found in a physical examination is enough to raise the suspicion of brucellosis. Early in the course of the disease the bacteria can be isolated in high numbers from the semen. Although this reduces with time the organism may shead for up to 2 years. Brucella can also be found in the urine for up to 3 months after infection. Blood cultures may also be used to grow the bacteria. Dogs, which show radiographic (x-ray) evidence of diskospondylitis (bridging of vertebrae), should be tested for brucella.

Serological testing of blood is available to detect antibodies against Brucella in infected animals. These antibodies become detectable around 6-12 weeks after infection. These blood tests are used as screening tests for breeding animals before mating to prevent spread of Brucellosis. Neutering or spaying is the suggested treatment for an affected dog, along with tetracycline or streptomycin antibiotics. Follow up blood tests every month for at least 3 months should be performed whilst treating the dog, during which time the infection should be decreasing and then eliminated. The treatment outcome is variable and prognosis for successful cure is guarded.

There are strong ethical considerations for owners and breeders with infected animals, but regardless of the value of the animal it should not be bred, distributed or sold. Pups from infected bitches may be infected too and so the same principles apply. Male dogs should be tested frequently and bitches should have a test performed before they come into oestrus. Any new dogs should be quarantined and tested twice at monthly intervals before integrating them with other animals in a breeding kennel.