What is Brucellosis?

There are four different types of known brucellosis species, three of which are mainly associated with livestock – cattle, swine, sheep and goats.  The fourth species and the focus of this article, Canine Brucellosis or Brucella canis, primarily affects dogs.  This disease is most commonly acquired by intact dogs, but it can affect altered dogs as well.  Note that all types of brucellosis can cross over to other animals besides their primary hosts, including humans.

Contraction of the disease

Brucellosis is normally thought of in terms of being a sexually transmitted disease acquired during the mating process.  Unfortunately, there may not be any symptoms of infection in either the male or the female at the time of breeding.  As a result, performing brucellosis tests on both dogs prior to breeding is an important safeguard breeders and stud owners can utilize.

Brucellosis may be shed in normal vaginal secretions, nasal secretions, and saliva and through the dam’s milk, urine, afterbirth and its associated fluids.  In addition to mating, a dog may become infected by ingesting any of these things or through oral contact.  Puppies can be infected in utero.

It can also be transmitted through artificial insemination (AI) if the male is infected.  This is true whether the AI uses fresh, chilled or frozen semen.  Vets usually require a brucellosis test on both dogs before they will perform an AI or collect semen for shipping or storage.

Unaffected dogs living with infected dogs of the same sex have been have been diagnosed with the disease within six months of being exposed to it.


Infected dogs may appear to be healthy. In pregnant females, brucellosis usually causes abortions and stillbirths.  Most of the abortions occur during the last three weeks of pregnancy.  If the pregnancy goes to term, the pups may die soon after birth.  Sometimes a female may appear to have fertility issues over multiple breeding cycles.

Males can have swollen scrotal sacs, testicular atrophy, decreased sperm counts and prostatitis.  Males can also be rendered infertile by brucellosis.

Infected dogs are usually infected for life.


Many vet practices have an in-house screening test for brucellosis.  There is a possibility of false-positive results, but a negative result from this test is highly accurate.  It is recommended that all breeding prospects be tested prior to mating.  A signed certificate by the vet will be given stating that the dog is negative for brucellosis.

If the screening test gives a positive result, then there are several alternative tests that can be used either to confirm the diagnosis or to classify it as a false-positive result.


There is neither a treatment proven to cure the disease nor a vaccine to prevent it.  A relapse of the disease is common, even after treatment.  Long-term antibiotics can help control the disease, but they do not eradicate it since the organisms can continue to survive in the tissues of the dog.  Once infected, animals will always be infected and able to infect other dogs.

At this time, the most commonly recommended practice is euthanasia of the infected dogs, whether they are breeding stock or pets.


Potential mates should be tested prior to breeding.  New breeding dogs brought into your kennel should be isolated and tested twice, a month apart, before adding them to the general population.  Dogs that do test positive should never be used for breeding.