Canine brucellosis is an infectious disease caused by the bacterium Brucella canis, which mainly affects the reproductive organs of canids of both sexes.

The natural transmission of brucellosis occurs in various ways. Females transmit the bacterium during estrus, with childbirth or following an abortion due to oral-nasal contact with vaginal secretions, males transmit it with seminal fluid and urine.

Puppies can be infected in utero, during childbirth or lactation and can remain intermittently bacteraemic for years. Infection may occur also by iatrogenic means(contaminated syringes) and blood transfusions.

The prevalence of infection varies according to age, breeding conditions, breed and geographic region. Pets in urban environments have a lower prevalence than stray dogs in economically depressed areas.  Labrador and the Beagle have a higher prevalence among the breeds.