Abstract Tuberculosis (TB) is a chronic disease caused by bacteria belonging to the Mycobacterium tuberculosis complex (MtbC). This disease rarely affects dogs. Canine infections are usually caused by M. tuberculosis. Mycobacterium bovis infections are rare in dogs and associated with consumption of raw milk or contaminated products. Here, we report a Boxer dog who had a M. bovis infection and was admitted to a Brazilian veterinary hospital with a presumptive diagnosis of chronic ehrlichiosis. Despite receiving treatment for chronic ehrlichiosis, it progressed to death. TB was diagnosed during post-mortem examinations using histopathological analysis. Ziehl-Neelsen staining revealed acid-fast bacilli in the kidneys, liver, mesentery, and a mass adhered to the liver. Further, PCR-restriction analysis was performed to identify mycobacteria in the samples. A restriction profile compatible with MtbC was found in the lungs. In addition, PCR-based MtbC typing deletions at different loci of chromosome 9 enabled the identification of M. bovis in the lungs. Therefore, it is very essential to perform differential diagnosis of TB in dogs with non-specific clinical signs and who do not respond to treatment, particularly those who had been in contact with TB-infected cattle or owners. Further, we highlight the use of molecular methods for the identification of bacilli, improving the diagnosis and aiding epidemiological studies.

Foram avaliados 304 cães de ambiente rural e urbano do município de Monte Negro, Rondônia, através do Antígeno Acidificado Tamponado (AAT), Soroaglutinação Lenta em Tubos (SAL) e 2-Mercaptoetanol (2-ME) para a pesquisa de anticorpos anti-Brucella abortus e da Imunodifusão em gel de ágar (IDGA) e Imunodifusão em gel de ágar com soro tratado com 2-Mercaptoetanol (IDGA-ME) para Brucella canis. Foram consideradas positivas as amostras reagentes nas provas confirmatórias do 2-ME e IDGA-ME. Verificaram-se 56 (18,4%) animais reagentes ao AAT e 12 (4,0%) reagentes a SAL. Apenas um cão (0,3%) foi considerado positivo, confirmado pela prova do 2-ME. Foram observadas 11 (3,6%) reações á IDGA, porém não houve confirmação na prova do IDGA-ME. Ressalta-se a baixa ocorrência de cães positivos ao 2-ME e a ausência de animais reagentes á IDGA-ME.

Serum samples from 304 dogs living in urban or rural areas of Monte Negro County, Rondônia State, Brazil, were evaluated for Brucella abortus reactivity using the Rose-Bengal Test (RBT), Standard Tube agglutination Test (SAT), and Mercaptoethanol Test (MET), and for Brucella canis reactivity using the Immunodiffusion test (AGID) and Immunodiffusion test with 2-Mercaptoethanol (ME-AGID). Serum was considered positive if reacted in the MET or ME-AGID. Fifty-six (18.4%) dogs reacted by the RBT, and 12 (4.0%) by the SAT. One (0.3%) dog was positive by the MET. Eleven (3.6%) dogs reacted by the AGID, but with no confirmation by the ME-AGID. It the small occurrence of dogs reacting by the MET and the absence of reactivity by ME-AGID is emphasized.