10. EVALUATION OF CARDIAC FUNCTION IN HYPOTHYROID DOGS USIING ELECTROCARDIOGRAHY AND ECHOCARDIOGRAPHY

The present study was carried out to evaluate cardiac function in hypothyroid dogs. ypothyroidism was diagnosed in 12 dogs based on clinical signs, normal or low serum triiodothyronine (T3), low tetraiodothyroxine (T4) beyond the reference range. The electrocardiographic changes noted were reduced PR interval, sinus arrhythmia, ventricular premature complex and low R wave amplitude in hypothyroid dogs. The major echocardiographic findings were increased interventricular septum thickness at end diastole, posterior wall thickness at end diastole and end systole. Mitral valvular insufficiency was diagnosed in five out of twelve cases on colour doppler study. The  electrocardiography and echocardiography was done again on 30th day of treatment with oral levothyroxine. Electrocardiography revealed persistence of low amplitude R wave and sinus arrhythmia. The echocardiographic parameters such as left ventricular internal diameter at diastole, end diastolic volume, stroke volume and cardiac output were lowered after one month of treatment.

Key words: Hypothyroidism, Electrocardiography, Echocardiography, Mitral valvular insufficiency