Disseminated tuberculosis in a dog: a putative zooanthroponosis

ABSTRACT

Background: Zooantroponoses that affect pets are rare. Microorganisms involved in human tuberculosis has great importance to public health and has potentiality to produce reverse zoonoses. Infection by Mycobacterium tuberculosis is in top of the most important infectious diseases related to public health. In dogs, the infection occurs through prolonged exposure to aerosols and respiratory secretions from humans. Canine tuberculosis is little reported and known in Brazil, this work aims to describe the anatomopathological findings of the first case of canine tuberculosis in a 5-year-old dog in the Federal District and alert to the presence of this disease in this region.Case The dog had history of close contact with its owner, who has been treated for pulmonary tuberculosis six months before. At necropsy scattered multifocal, firm, white to yellow-gray nodules, varying in size (3 mm to 10 mm) involving lungs, kidneys, heart, liver and spleen was observed. In frontal and occipital cerebral cortex, pale-gray circular lesions were detected with the same characteristics. The histological findings were, multifocal to coalescent granulomas, well organized with a central core of necrosis with foci of mineralization, surrounded by histiocytes, epithelioid macrophage, rare Langhans giant cells, some intact and degenerate plasma cells and neutrophils, and a rim of reactive fibroblasts producing fibrous connective tissue. Histological staining with ZN revealed free acid-fast bacilli and in the cytoplasm of macrophages and granulomas in all affected organs. The PCR allowed identification of DNA was extracted from formalin fixed paraffin embedded (FFPE) tissues using the ReliaPrep™ FFPE gDNA Miniprep System®, according to the manufacturer’s instructions (Promega, EUA). The Speed-Oligo Mycobacteria assay was used to identify the presence of M. tuberculosis complex DNA in tissue samples.[...]