Description: Fifteen clinically healthy non-pregnant 4-year-old Iranian Najdi does were divided into 3 equal experimental groups (n=5) and received different doses of furosemide intravenously (Group 1: 2.5 mg.kg-1; Group 2: 5 mg.kg-1 and Group 3: 10 mg.kg-1). Electrocardiogram recordings and blood samplings to evaluate serum sodium, potassium, chloride, calcium, magnesium and phosphorus concentrations were performed prior and 1, 2, 3, 4, 5 and 24 hours after furosemide administration. In Group 3, R amplitude at 5th hour was significantly different from other experimental groups (P=0.001) and significantly higher than baseline level (P=0.001). P-R, R-R and S-T intervals in Group 3 at 5th hour were significantly higher than in other groups (P<0.05). These parameters in Group 3 at this time were significantly higher than baseline values (P<0.05). In all 3 experimental groups, serum concentrations of sodium, chloride and potassium at 5th hour were significantly lower than baseline levels at hour zero. It may be suggested that changes of electrocardiographic parameters after furosemide administration are due to alterations of the electrical conduction of action potential in the myocardium