Abstract
Bacteriological investigation of canine brucellosis in Mexico City revealed a high rate (11.8%) of Brucella canis infection in a sampling of 59 stray dogs. When conservative criteria were employed in the interpretation of serological test results, there was general agreement between the serological and bacteriological findings; however, some animals with localized male genital tract infections could not be judged as infected solely by serological tests. All Mexican field isolates were identified as B. canis; however, some diversity was observed as regards nitrate reduction, growth in the presence of basic fuchsine, and the degree of mucoidness. The seemingly high prevalence of B. canis infection in Mexico City dogs suggests the need for further inquiry into the possible public health significance.