Hereditary dilated cardiomyopathy in Holstein-Friesian cattle in Japan: association with hereditary myopathy of the diaphragmatic muscles.

This report deals with the pathology and genetic basis of dilated cardiomyopathy in 10 Holstein-Friesian cows aged 3-6 years, a disease similar to that reported in Simmental-Red Holstein and Holstein-Friesian cattle in several other countries. The main clinical signs were associated with systemic circulatory failure, and at necropsy the animals showed cardiomegaly, severe congestion and fibrosis of the liver, and systemic cardiac oedema. Histologically, hypertrophy and vacuolation of the cardiac muscle fibres and severe fibrosis were noted. Electron microscopically, the sarcoplasm of the hypertrophic fibres was seen to be filled with fine structures of low electron-density, together with thin filamentous material, suggesting myofibrillar lysis. The mitochondria showed increased size, an abnormal cristae pattern and vacuolation due to partial loss of cristae. Pedigree analysis of the affected cattle indicated an autosomal recessive mode of inheritance. The family line of this cardiomyopathy overlapped with that of hereditary myopathy of the diaphragmatic muscles in Holstein-Friesian cattle, the pathological aspects and inheritance mode of which were reported previously. The available evidence suggested a genetic association between these two pathologically distinct diseases.