Abstract / Summary
Abstract Bovine dilated cardiomyopathy (BDCM) has been described predominantly in the Holstein-Friesian breed worldwide, whereas autophagic vacuolar cardiomyopathy (AVCM) has been less frequently reported in humans. Of comparative pathologic significance, both consistently exhibit sarcoplasmic vacuoles in cardiomyocytes. Pathologic examination was conducted on an 8-year-old Holstein-Friesian slaughtered dairy cow that was clinically diagnosed with idiopathic heart failure. Grossly enlarged with prominent dilation of the right ventricle, the heart histopathologically exhibited distinctive myocardial lesions characteristic of CM. Among a variety of regressive morphologic changes observed in cardiomyocytes were sarcoplasmic deposition of autofluorescent lipofuscin and substantial appearance of lipofuscin-pigmented vacuoles that were considered to be autophagic ones. There was also a marked interstitial fibrosis associated with infiltrates of small numbers of CD3 + T cells and macrophages that phagocytosed lipofuscin pigments. Viewed from a histopathogenetic perspective, the myocardial lesions were likely to be relevant to an autophagy-related process involved in lipofuscinogenesis. Although a disease entity of AVCM was a consideration, this bovine case would be most appropriate to be categorized as a phenotypic variant of BDCM, on the basis of the breed occurrence, clinical characteristics, gross findings, and nature/severity of the histopathologic lesions in the myocardium.