Brucella canis

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Description and Significance

Brucella canis are gram negative proteobacteria within the Brucellacae family. B. canis is a facultative intracellular pathogen that can survive well outside a host, but prefer to reproduce within the host (“Brucella”). When first found Brucella canis was one of many species of Brucella, but in 1977 it was determined that the only species is Brucella melitensis and the others are just at subtypes of the species. The subtypes only exist for their differences in the animal host it prefers and phenotypic appearance. Brucella canis is one of the subtypes with the preference for dogs as its host. Brucella species was first found by a British doctor named Davis Bruce, hence the name Brucella. In the 19th century in Malta an unknown disease known as Malta fever caused British soldiers to become ill. Bruce determined that the causal agent of the disease was from a bacterium found in milk from infected goats (“Brucella”). The bacterium first gained recognition in the United States as the causal agent of massive abortions that occurred amongst female beagles. The bacterium was then determined to be the causal agent of the infectious disease brucellosis in female and male dogs, which causes abortions and infertility. Dogs may be man’s best friend except for if it is infected by the bacteria, which can cause spread of brucellosis into the human population (“Canine Brucellosis Caused by Brucella Canis”).

Cell Structure and Metabolism

Brucella canis are small, rough, rod shaped bacteria.

Ecology

Brucella canis are more prone to areas in the world of poor sanitation or that lack good public health safety. Australia and New Zealand may be the only areas of the world that do not contain the bacteria. B. canis can withstand various environmental changes ranged from very high temperatures, lack of sunlight, feces, and clothing.

Pathology

B. canis can penetrate mucous membranes within the oral cavity, vagina and conjunctival of dogs. The bacteria are found living within the uterine tissue and secretions of female dogs and are shed for months after an abortion. The bacteria found in the semen, testicles, and urine of male dogs and are shed the bacteria for years after infection. B. canis can live within a dog for years before it gets rid of the infection. B. cains is transmitted from dog to dog sexually through vaginal and semen secretions. The bacteria can release from infected dogs by secretions that exit the mouth and nose, and through scars or cuts on infected dogs. Although, dogs are the common host for B. canis infected dogs can cause spread to humans by direct contact with humans usually by just touching an infected dog.

Treatment

Once a dog is infected by Brucella canis it is difficult for the dog to become fully cured. Finding an effective treatment for brucellosis has been very difficult because the bacteria are embedded with the mucous cells of the animal. Antibiotics have been found to have some effect on dogs infected with the bacteria, but only by using many different antibiotics. The problem with antibiotics is that the dog may relapse and the bacteria count is only reduced and not completely removed regardless of the use of the antibiotics. A method of spraying has been used on dogs to reduce spread of the bacteria to others, but unfortunately like the antibiotics it does not remove the bacteria. Long after the bacteria have been successfully treated the dog may still release the bacteria making it difficult for them to try to reproduce after it is claimed to be cured.

Prevention

All breeding dogs are tested year round to prevent the spread of Brucella canis. Infected dogs are isolated immediately for other dogs and not allowed to breed even after it may be cured.

Reference

Centers for Disease Control and Prevention.Brucellosis. 2007. 21, Apr. 2009 <http://www.cdc.gov/ncidod/dbmd/diseaseinfo/Brucellosis_g.htm>

Drs. Foster & Smith, Inc. Brucellosis (Brucella canis) & Abortions in Dogs. 1997. 21 Apr. 2009 <http://www.peteducation.com/article>

Wikimedia Foundation, Inc. Brucella canis. 2009. 21 Apr. 2009 <http://en.wikipedia.org/wiki/Brucella_abortus>