HEMODYNAMIC EFFECTS OF HYPOTHYROIDISM INDUCED BY ADMINISTRATION OF METHIMAZOLE TO EUTHYROID DOGS

This study was carried out in order to determine the possible effects of methimazole upon the invasive parameters of the cardiac functions of the dogs. Ten dogs was used in this study. In the begining of the study and 8 weeks after orally administration of methimazole (30 mg/kg), serum T4, T3 and TSH concentrations and contraction (LVCT) and relaxation times (LVRT), systolic (LVSP) and diastolic pressures (LVDP) of left ventricle were measured. After weeks, serum T4, T3 concentrations. LVSP and LVDP were significantly decreased, while TSH concentrations was significantly increased. However, increasing in the LVCT was no important. No difference was observed between the LVRT of healty and hypothroid dogs. The results of the present study suggested that methimazole caused significant changes in serum thyroid hormone concentrations as well as the left ventricle pressures of dogs.