Cardiomyopathy in generalised glycogenosis type II in cattle

The clinical, electrocardiographic and postmortem findings in five cattle affected by generalised glycogenosis type II are described. Three of the affected animals showed generalised muscle weakness for some months before being killed at 11, 15 and 16 months of age. Of the remaining two, one developed severe respiratory distress when 3 months old and died within 6 h of first being noticed to be ill. The other animal showed respiratory distress on exertion at 5 months of age, became recumbent and died when 7 months old. The sum of the QRS complex amplitudes in ECG leads I, II, a VR, aVL and aVF of the affected animals was significantly increased from the control or carrier animals, but only the two affected animals which showed clinical and pathological signs of congestive heart failure had increased heart weight to body weight, left and right ventricular weight to body weight ratios. In view of the lack of correlation between the increased QRS amplitudes and the presence of cardiac enlargement, it is suggested that the increased QRS amplitudes are a reflection of a conduction disorder. It is further suggested that QRS complex abnormalities in generalised glycogenosis in man, particularly in the late onset form may be due to a similar phenomenon.