Brucella canis: the other Brucella
Brucellosis can be a pretty nasty disease. Most people with brucellosis are infected through ingestion of contaminated food or contact with infected farm animals. Brucella abortus, B. melitensis and B. suis are the most common bacterial species involved. However, there is also another Brucella species, B. canis, which (as the name implies) is associated with dogs. Human infections with B. canis are much less commonly diagnosed than those caused by other Brucella species, but it is possible that this infection actually occurs more often than we realize.
Brucellosis can cause a wide range of problems, but most are rather non-specific such as fever, headache, body aches, sweating and back pain. Recurrent, undulating fever is a common sign and can persist for long periods of time. Disease caused by B. canis is similar to that caused by other Brucella species, but one reason this disease may be underdiagnosed is that screening tests for brucellosis do not cross-react with B. canis. Therefore, a physician might suspect brucellosis, but if the initial test (an antibody test) is negative, the physician is likely to move on to investigate other possibile diagnoses. Specific B. canis blood tests or culture of B. canis from blood or infected sites are required for diagnosis. Overall, it's probably still a very rare disease, but one that certain people should be aware of.
Many dogs that are infected with B. canis have no detectable signs of infection. The bacterium can circulate through the body continually or intermittently, and spread from the gentials (where it likes to reside) for years. Some infected dogs show signs of illness. Reproductive problems, including late-term abortion (miscarriage) and decreased fertility are major problems. Fever, lymph node swelling, diskospondylitis (infection in the spine) and other problems can also develop.
The risk of human exposure is highest in people in close contact with breeding animals, particularly people in contact with dogs that miscarry during pregnancy or kennels with reproductive problems. Most reported human infections involve people in close contact with dogs that miscarry. The risk to owners of household pets (especially neutered pets) is presumably very low.
- People who have been exposed to dogs that miscarry and who subsequently develop signs like fever and aches should make sure their physician considers B. canis infection.
- HIgh risk people (very young, elderly, immunocompromised, or pregnant women) should avoid contact with dogs that have miscarried, or dogs from kennels with reproductive problems or known B. canis infection.
- Care should be taken when handling dogs that have miscarried or are in the process of doing so. Gloves should be worn when handling the dog, aborted fetuses and any potentially contaminated items. Uterine (birth) fluids can have very high levels of B. canis.
- Hands should be washed regularly and after removal of gloves.
- If abortion or reproductive problems are identified in a kennel, testing for B. canis should be performed. If present, an eradication program should be started.
More information on brucellosis in dogs can be found in the Worms & Germs archives.
Canine brucellosis in a puppy mill
ProMed recently reported about an outbreak of canine brucellosis at a "puppy farm" in Ireland. Farm is definitely the appropriate word in this case, since this operation had about 700 breeding females. The picture on the right is not from this farm, but I imagine it's a similar operation. Beyond the concerns about humane management of dogs under these conditions, such a large operation creates perfect conditions for various infectious diseases.
"The farm's owner has refused to sign an undertaking not to move the dogs off-site before an official inspection can take place to investigate the extent of the [brucellosis outbreak]."
Lack of cooperation makes any disease investigation much more difficult. It's not surprising this person doesn't want to cooperate, given the type of operation he's running.
"Someone from the farm told the Irish Times that the 2 animal welfare agencies were involved in acts of "intimidation" against the establishment."
I suspect that "intimidation" in this case means the agencies were doing their job, because I can't see how there wouldn't be significant welfare problems at a farm of this type and size.
"'We got accurate information on Friday [2 May 2009] that this man was intending moving and selling these dogs and we acted on it,' according to Jimmy Cahill, chief executive of the DSPCA [Dublin SPCA]. 'The guards were very helpful but the owners refused to let us see the dogs or any of the carcasses.' "
The reference to "carcasses" implies that deaths have occurred. Death from B. canis in dogs is very rare but it is possible. However, a poorly managed operation with hundreds of dogs is bound to have multiple issues that could cause deaths.
Canine brucellosis is caused by the bacterium Brucella canis. This main problem with this bacterium in dogs is reproductive disease, including abortion and infertility (in both males and females). Discospondylitis (inflammation of the discs between vertebrae in the back) can also develop.
Brucella canis is a zoonotic organism. Human infections are rarely reported but it is possible that some go undiagnosed. Brucella canis can be transmitted from dogs to people through contact with body fluids from infected dogs, including urine and vaginal fluids. The risk of transmission is likely highest when handling animals during breeding or birthing. While the bacterium can be shed in nasal secretions and saliva, levels are low in these fluids and the risks are probably correspondingly low.
One problem with preventing B.canis transmission is that infected dogs do not necessarily show any signs of disease. In people, B. canis infection can cause flu-like disease, loss of appetite, weakness, joint and back pain, vomiting and diarrhea and various other symptoms.
To control the outbreak on this "farm," quarantine and repeated testing of all dogs is needed, and positive animals must be removed from breeding. Given the information provided above, it's pretty unlikely this will happen voluntarily. I suspect this person would likely either just get rid of these dogs and get more poor-quality breeding animals, or try to continue breeding these dogs and hope people get sick of looking into his operation.
Brucellosis in dogs
Brucellosis is an infection caused by bacteria of the genus Brucella. The most common species of Brucella in companion animals is Brucella canis, which typically causes infection in dogs. This bacterium is very rare in Ontario - in a survey of 2000 dogs, only 0.3% had evidence of exposure to B. canis. So it was unusual that a case of canine brucellosis was recently diagnosed in the province, until it was discovered that the dog originally came from a rescue shelter in the southern USA - an area where exposure to the bacterium is much more common (approximately 8% of dogs).
Brucellosis in dogs typically causes reproductive problems such as infertility and an enlarged scrotum in males, and late-term miscarriage in bitches (breeding females), with few or no other signs of clinical illness. But in some cases the bacteria have been found to infect tissues other than the reproductive tract, including intervertebral discs (leading to back problems), the eyes, the kidneys, or the tissues around the brain and spinal cord (i.e. the meninges). The bacteria, and antibodies to the bacteria, can be very difficult to detect in the early stages of infection. The infection is usually diagnosed by a blood test, but it may take 8-12 weeks before test will yield a positive result. There are also problems with high numbers of false-positive test results due to cross-reaction with other species of Brucella. Any positive test result should therefore be confirmed by a second, different laboratory test.
Human infection with any species of Brucella is now uncommon. When illness does occur, the signs are often non-specific (e.g. fever, headache, myalgia), but more severe infections have been reported. Transmission of B. canis from an infected dog to a person is possible. The bacterium is transmitted by contact of a mucous membrane (e.g. eyes, nose, mouth) with blood, urine, milk, semen, or vaginal discharge from an infected animal. The highest-risk materials (i.e. most likely to contain a high number of the bacteria) are placental tissues and fluids that are passed during whelping (delivering puppies). Treatment for infection is available, but the course is often long and recurrence of infection can occur.
Although brucellosis is very rare in dogs in Ontario (and Canada in general), here are a few things you can do to help avoid B. canis:
- Always wash your hands right away if you accidentally come in contact with blood, urine, milk, semen or vaginal discharge from any dog.
- Prevent contact between your dog and urine, milk, semen or vaginal discharge from other dogs, especially if you travel with your dog to an area where the prevalence of B. canis is relatively high (such as the southern USA).
- Dogs used for breeding should be tested for B. canis. Many breeders will require dogs to be tested before allowing their animal(s) to be used, because the infection can be transmitted through breeding and can have such detrimental effects on fertility.
- Newborn pups should be handled as little as possible, but if you must handling them wear disposable gloves and wash your hands as soon as you take your gloves off. Exercise the same precautions when cleaning up the area where a bitch has whelped.
More information about brucellosis can be found on the CDC's Brucellosis website.
