Morphological characteristics of the cardiac muscle in calves showing clinical signs of myocardiodystrophy
Tests performed on newborn calves showing clinical signs of myocardiodystrophy reveal a moderate sinus tachycardia or a sinus bradycardia, rare extrasystoles, a decrease in the amplitude of the QRS complex and an increase in its duration, and incomplete bundle branch blocks. The diagnostic criteria were repolarization abnormalities such as flattening or inversion of T-waves coupled with downsloping ST segment depression.
A patomorphological examination of the hearts of fallen calves showed a cardiac damage in the form of subacute interstitial myocarditis, both diffuse and focal in distribution; in most cases the right side of the heart was affected. The right ventricle was most severely affected, with mainly inflammatory infiltrates localized in the cardiac myocytes and around the capillaries. The intramural inflammatory infiltration had a diffuse interstitial pattern. The right ventricle (on the arteriole side) showed evidence of the proliferative vasculitis. The changes observed in cardiac myocytes included partial granular degeneration, focal necrosis, and even myolysis of some cardiac myocytes.
Keywords: calves, electrocardiography (ECG), myocardiodystrophy, morphology, myocard