Furosemide Induced Electrocardiographic Alterations in High Producing Holstein Dairy Cows

Diuretics have several therapeutic advantages in dairy cows but there are different side effects such as acid-base and electrolyte imbalances which may affect the electrocardiographic parameters. Fifteen multiparous, clinically healthy, non-pregnant and high producing 4-year-old Holstein dairy cows at their early lactation period were randomly divided into 3 equal experimental groups. Furosemide was infused intravenously at 3 different doses containing group 1: 2.5 mg/kg; group 2: 5 mg/kg and group 3: 10 mg/kg. Electrocardiogram recordings and blood samplings were performed at prior and 1, 2, 3, 4, 5 and 24 hours after furosemide administrations. Sera after separation were assayed for sodium, potassium, chloride, calcium, magnesium and phosphorus concentrations. There were no significant changing patterns in P, R, S and T amplitudes. P-R, R-R, Q-T and S-T intervals increased significantly after furosemide administrations in groups 2 and 3. Electrocardiographic intervals in groups 3 were higher than other groups (P 0.05). The values of P, R, S and T durations in group 3 increased significantly after furosemide administration. Durations of these waves in group 3 were higher than groups 1 and 2, significantly (P 0.05). There were no significant changing patterns in serum calcium, magnesium and phosphorus levels. Serum concentrations of sodium, potassium and chloride significantly decreased after furosemide administrations in all experimental groups. Levels of these electrolytes in group 3 were significantly lower than other groups (P 0.05). It may be stated that furosemide affects the electrocardiographic parameters by misbalancing the serum electrolytes which affect the electrical conduction of action potential in the myocardium.