Visceral leishmaniasis (VL) is a chronic, often fatal infectious disease caused by Leishmania infantum chagasi in the Americas. The disease can affect many organs and may express different clinical forms. However, the involvement of the heart has rarely been reported in dogs infected by Leishmania sp. Thus, we describe a case of chronic myocarditis with clinical and pathological effects in a dog naturally infected by Leishmania infantum chagasi. Positivity for Visceral Leishmaniasis was determined by the presence of anti-Leishmania sp. in serological tests (IFAT, ELISA and DPP) and confirmed by visualization of amastigote forms of the parasite in the popliteal lymph node aspiration samples. The cardiovascular clinical examination showed changes in the radiographic, ECG, blood pressure and heart biomarkers. After euthanasia, heart tissue samples were histologically examined and underwent our immunohistochemistry assessment, where mononuclear infiltrate was observed (plasma cells, lymphocytes and macrophages) with the presence of rounded brownish-yellow (immunomarked) cells, indicating amastigotes of Leishmania infantum chagasi within the myocardium. The etiopathogenic aspects of visceral leishmaniasis in the myocardium in this case may be related either to the presence of the parasite or the "nonspecific reactive" response of the tissue attributable to the aggression of the parasite in the body. However, it is not known if the strains of Leishmania infantum chagasi found in the semi-arid of Paraíba have some tropism for cardiac tissue or if they induce immunological cross-reaction with clinical implications.
dog; myocarditis; Leishmania infantum chagasi; immunohistochemical; troponin I
