Canine Brucellosis

Written by Dr. Patty Khuly, VMD MBA

Summary

Brucellosis is a canine bacterial disease caused by the organism known as Brucella canis. This kind of bacteria affects the reproductive tract of both male and female dogs. Though it's typically transmitted via bodily fluids during reproduction, it can be spread by any direct contact with infected fluids. Airborne transmission is possible but considered extremely rare.

Brucellosis is particularly problematic because the infection has a way of spreading rapidly among individuals, especially when dogs are housed in close quarters (such as kennel settings where managed breeding often takes place). Perhaps this infection's worst feature, however, is that it can be transmitted to humans.

Brucella canis is a wily bacterium; it is intracellular (lives within cells) and can thereby avoid easy detection as well as many treatments. Fortunately, infection can almost always be prevented via the sound animal husbandry practices detailed below.

Symptoms and Identification

Though the classic sign of brucellosis is abortion late in a bitch's pregnancy, many dogs won't show any signs of brucellosis whatever.

In females, signs of brucellosis may also include (but are not limited to) the following:

  • Stillbirth

  • Failure to conceive

  • Reabsorption of litters

  • Swelling of lymph nodes

In males, signs of brucellosis include (but are not limited to) the following:

  • Inflammation of the epididymis

  • Swelling of the prostate

  • Visible swelling of the testes

  • Swelling of lymph nodes

In some unusual cases, chronic disease from long-term stimulation of the immune system may result. This can include one or more of the following:

  • Diskospondylitis (inflammation of an intervertebral disc in the spine)

  • Uveitis (inflammation of the uvea of the eye)

  • Polyarthritis (multiple joint arthritis)

  • Glomerulonephritis (kidney inflammation and the subsequent protein loss that results)

Diagnosis of brucellosis can be tricky since the bacterium is difficult to culture, but typically comes down to the use of one or more of the following tests:

  • Rapid Slide Agglutination Test (RSAT): This test can detect even tiny amounts of the Brucella organism. Unfortunately, it can't easily distinguish between Brucella bacteria and others that may be closely related. In other words, false positive results are common (up to 60%). The good news is that a negative is always a definitive finding and there can be no question of infection once negative test results are received. Positive dogs, on the other hand, will require advanced testing to determine their brucellosis status.

  • Immunofluorescent Antibody (IFA) test: This is a similar, if not as popular, screening test. As with the RSAT, false positive results indicate a need for further testing.

Advanced testing includes:

  • Tube Agglutination Test (TAT): This one identifies antibodies against Brucella. Unfortunately, false negatives can occur with this test.

  • Agar Gel Immunodiffusion (AGID) test: This test, which identifies a certain protein on the Brucella organism, is considered the most accurate test.

Affected Breeds

All breeds of dogs appear to be equally susceptible to infection by the Brucella organism.

Treatment

Treatment is considered extremely difficult; one issue is that the intracellular nature of this bacterium makes treatment using antibiotic drugs very unlikely. Because of this difficulty, breeding dogs who test positive are almost always retired (spayed or neutered).

To make up for the deficiency of a single antibiotic, a combination of many different antibiotics is typically elected. While these will usually help reduce the amount of bacteria in the blood stream, they will seldom eradicate the bacteria entirely. Treatment for life is often necessary.

Sadly, this is why so many brucellosis-positive dogs are euthanized. Many breeders consider euthanasia preferable to the possibility of exposure that persists when affected dogs are treated and allowed to interact with uninfected dogs.

Veterinary Cost

The cost of care for brucellosis is largely relegated to the testing that must be undertaken each time dogs are bred. When testing does prove positive, however, the veterinary expense incurred depends upon whether owners elect to treat or not.

If treatment is pursued, the cost of serial treatment and many rounds of potentially expensive antibiotics may prove expensive. Depending upon the clinician's choice of antibiotics and the size of the dog, the antibiotics alone may cost upwards of $1,000 for a few months. These costs rise to many more thousands if a lifetime of antibiotic therapy is needed.

Prevention

Unfortunately, there's no vaccine to prevent brucellosis. However, there are plenty of ways pet owners can keep their dogs from contracting the disease:

  • Dogs who test positive for brucellosis should never be bred.

  • If pets are not used for breeding, owners should consider this sexually transmitted disease one more reason to spay and neuter.

  • Owners should not keep non-breeding dogs in a kennel where breeding dogs are typically housed.

  • Before breeding, owners should have both male and female tested by their veterinarians. Owners of each dog should ask for the other's test results to verify their brucellosis-negative status.

  • Disinfection of the area where breeding dogs are housed is important as well.

  • Known carriers should be isolated and their area disinfected daily.

References

US Centers for Disease Control and Prevention: http://www.cdc.gov/brucellosis/

The Merck Veterinary Manual: http://www.merckmanuals.com/vet/reproductive_system/brucellosis_in_dogs/overview_of_brucellosis_in_dogs.html?qt=brucellosisandalt=sh