Canine Brucellosis Caused by Brucella canis

Brucella canis is sexually transmitted by the mating of infected males and females.

In males, the main sign is epididymitis of one or both testes, and infertility. Testicular atrophy and a moist scrotal dermatitis may be present. Semen from infected males usually contains large numbers of abnormal sperm and inflammatory cells, especially during the first 3 post-infection months. Chronically infected males may have no sperm, or reduced numbers of immature sperm. Autoimmune (anti-sperm) antibodies are present and probably contribute to male infertility. Nonspecific signs in both sexes include lethargy, loss of libido, premature aging and generalized lymph node enlargement. B. canis has been isolated from field cases of diskospondylitis, a condition that also has been reproduced experimentally in SPF dogs. Recurrent uveitis has been occasionally reported in infected dogs after several weeks/months of infection.

 

Infected males harbor organisms in the prostate gland and epididymides for several months. Bacteria are disseminated the seminal fluids and, occasionally, urine. In males, the main sign is increasing infertility. Testicular atrophy and a moist scrotal dermatitis may be present. Semen from infected males usually contains large numbers of abnormal sperm and inflammatory cells, especially during the first 3 post-infection months. Chronically infected males may have no sperm, or reduced numbers of immature sperm. Autoimmune (anti-sperm) antibodies are present and probably contribute to male infertility. Nonspecific signs in both sexes include lethargy, loss of libido, premature aging and generalized lymph node enlargement. B. canis has been isolated from field cases of diskospondylitis, a condition that also has been reproduced experimentally in SPF dogs. Recurrent uveitis has been occasionally reported in infected dogs after several weeks of infection.
Infected males harbor organisms in the prostate gland and epididymides for several months. Bacteria are disseminated the seminal fluids and, occasionally, urine. B. canis is short-lived outside the dog, 

Treatment is expensive and cures are difficult to achieve, especially in chronically infected males. Repeated blood cultures and serologic monitoring is required . Recrudescence of the infection after the cessation of antibiotic treatment is common. Even if the organism can be successfully eliminated, males frequently remain sterile because of irreversible damage to the testes and epididymides. Spaying or castration is believed to reduce the risk of transmission from infected dogs; however, this hypothesis has not been tested experimentally and neutering does not eliminate organisms from the body. All neutered dogs should receive a course of antibiotics. The most successful and practical treatment results have been obtained with a combination of a tetracycline drug, e.g., tetracycline hydrochloride, doxycycline, minocycline, and streptomycin administered during the first 3 months of infection. More than 80% cure rates have been achieved in kennels, where dogs initially diagnosed as infected were euthanized and additional ("early") cases were treated. A cure is more difficult to achieve in chronic infections.
If available, dihydrostreptomycin (10 mg/kg IM bid) is given for the initial 7 days of treatment together with a tetracycline antibiotic (25 mg/kg orally tid), which is continued for 4 weeks. During the last 7 days of tetracycline therapy, streptomycin is again given. In some instances where the first course failed, a second course of treatment has been successful. Since streptomycin is no longer available in the USA for treatment of dogs, gentamicin has been recommended by some clinicians as a substitute antibiotic. However, there is insufficient data to recommend gentamicin, and preliminary studies indicate that its efficacy is unsatisfactory, except in very early cases - i.e, in dogs infected for less than 1 - 2 months. Treatment is not recommended for breeding dogs, or when long-term (3 months) follow-up is unlikely. Treatment failures are especially common in infected males where organisms are commonly sequestered in the prostate gland and epididymides.
Testing and elimination of infected dogs is the only proven method of eradication of B. canis from an infected kennel. An attempt should be made to identify the source of the infection - unfortunately, this has rarely been accomplished since breeders are reluctant to admit culpability.

Management of infected dogs is time consuming and expensive. Veterinarians must be prepared to address owners' concerns and render judicious advice, which may vary according to circumstances. Prevention is essential to avoid the ordeal of infection in a breeding kennel. As soon as canine brucellosis is diagnosed in a kennel, vigorous measures must be implemented until the disease has been eradicated. Infected kennels should be quarantined, even though most countries do not have formal regulations. Lack of such measures has lead to widespread,  international, spread of B. canis infection.

Spay or castrate + treatment. Treatment uncertain; chances greater for success in early infections. Follow-up serology for 3 months post-treatment. : Uncertainty of treatment; cost great; disappointment common.

 In male dogs, infection of the testicles can lead to infertility due to anti-sperm antibodies developed as the body attempts to fight off the bacterial infection. The testes may atrophy after the initial period of swelling. Scrotal enlargement or infection of the skin over the scrotum may be seen

In both female and male dogs there may be infection of spinal discs (diskospondylitis) which can cause back pain and rear leg weakness or even paralysis. Eye inflammation may be seen in either sex.

It is not usually possible to culture Brucella canis bacteria from the blood or affected tissues so diagnosis is usually done by titer testing. There is a kit available to veterinarians for testing in their office. It is usually best to retest any dogs found positive on this test with other testing methods since there is a fairly high rate of false positives using the in-house test kit.

Brucellosis is very difficult to treat successfully. A combination of minocycline and streptomycin is thought to be most effective but is expensive. Tetracycline can be substituted for the minocylcine to reduce costs but also lowers the effectiveness of treatment. All infected animals should be neutered or spayed to prevent sexually related transmission. All infected animals should be considered to be lifelong carriers of the disease, even if treated.

It would probably be best not to breed dogs without testing both the male and female for this disease. Breeding should be a deliberate choice -- not a random event! For breeding kennels, routine isolation of new dogs would be a very good idea. After isolation and negative tests at entry into the kennel and one month later, it should be safe to let the new dog mix with the others in the kennel. If infection is suspected at any time, quaternary ammomium (like Roccal Rx) and iodophor (Betadine Rx) disinfectants can kill Brucella organisms in the kennel to limit spread of the disease.

One last thing. It is possible that brucellosis caused by Brucella canis may be a zoonotic disease -- meaning that people could potentially be infected by this organism.  It is something to think about when handling infected dogs. Wear gloves around any body fluids and be careful about contaminating yourself in any way.

Brucella canis is sexually transmitted by the mating of infected males and females. An infected male will spread the brucella bacteria via his semen and urine.Usually the bitch appears healthy with no signs of disease or indication that she is a carrier of the bacteria. She can spread brucella to other animals through her urine, aborted pups, or more commonly at mating. Once pregnant, the bacteria will also infect the developing foetuses causing illness.

Litters of infected bitches are often aborted in the last two weeks of gestation, or the puppies may die shortly after birth. The aborted pups are usually partially decomposed and accompanied by a grey to green vaginal discharge, which can contain high levels of bacteria. People should avoid contact with dead foetuses or discharges from aborting dogs. The long term infected dog normally becomes sterile.

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Updated 20-06-05