Subacute massive necrotizing myocarditis by canine parvovirus type 2 infection with diffuse leukoencephalomalacia in a puppy.

Severe necrotizing myocarditis associated with canine parvovirus type 2 (CPV-2) infection and diffuse leukoencephalomalacia was recognized in a 4-week-old mongrel puppy. The cardiac lesions were characterized by severe diffuse myocardial degeneration and necrosis with occasional massive mineralization and distinct intranuclear inclusion bodies. Immunohistochemical examination revealed the presence of CPV-2 antigens in both the cytoplasm and nuclei of the myocytes. In the white matter of the cerebrum, moderate to severe diffuse necrosis with diffuse infiltration of gitter cells and occasional diffuse mineral deposits were recognized symmetrically and bilaterally. In the meningocortical area of the cerebellum, there was mild focal hemorrhage and accumulation of hemosiderin-laden histiocytes. In addition to the absence of viral antigen (as judged by immunohistochemistry), neither viral inclusions nor other vascular lesions were identified in examined sections of brain. These findings suggest that the brain lesions were not induced by direct CPV-2 infection but were related to severe myocardial lesions producing prolonged hypoxia and/or ischemia.