MULTIFOCAL FIBROSING MYOCARDITIS IN A DOG.

Introduction: Heart failure associated with chronic myocardial fibrotic lesions is not common in the dog, and it can be related to chronic infectious myocarditis and infarcts. Immunomediated myocarditis is described in humans. Most commonly, immunomediated disorders in the dog affect the skin. Materials and Methods: Here we present an unusual case of a dog, 7-years old, dachshund, male, with multifocal cutaneous lesions, that died of heart failure with liver involvement after prolonged cortisone treatment. Results: Necropsy showed cutaneous, hepatic and heart lesions. Hepatomegaly was associated with multifocal nodular whitish lesions and accentuated lobular pattern. The skin showed multifocal alopecia and plaque-like oval lesions. Grossly the heart manifested mild multifocal ventricular whitish discolouration. Histology evidenced unusual atrophic and fibrotic lesions in the heart with a focally extensive infiltrate of mononuclear lymphoid cells. In the liver a pattern of porto-portal severe degeneration and cholestasis was observed with lack of the smaller bile ducts. In the skin a chronic hyperplastic plaque-like dermatitis was present with infiltration of mononuclear lymphoid cells. Immunohistochemistry revealed a mild positive reaction to CD3 and CD5 in the skin and heart infiltrate with rare CD79+/CD20+ cells. All major infectious diseases were excluded. Discussion (and/or Conclusions): On the basis of these results, a chronic hepatic disorder with associated cutaneous involvement and chronic heart damage was diagnosed. An immune-mediated disorder as primary cause is discussed with review of the literature. The lymphoid infiltrate in the heart and skin show signs of atypia and a progression to lymphoma is also considered