Evaluation of the short-term echocardiographic effects of two loop diuretics, furosemide and torsemide, in a group of dogs

Background: Two loop diuretics, torsemide and frusemide, can affect the urinary system and consequently the cardiordiovascular haemodynamics in different ways.

Objectives: This study compared a number of echocardiographic parameters and systemic arterial blood pressure (ABP) changes following administration of furosemide or torsemide.

Methods: Five shelter dogs underwent transthoracic two-dimensional M-mode echocardiography to obtain the following measurements: left ventricular internal dimension at end-systole (LVIDs), left ventricular internal dimension at end-diastole (LVIDd), fractional shortening (FS), heart rate (HR) and the distance between the mitral valve socket and the ventricle wall (septal to E Point, SEP). Arterial blood pressure was measured using the oscillometric method. Measurements recorded before treatment (baseline data) were compared to those after the dogs received furosemide (5 mg/kg) or torsemide (0.5 mg/kg).

Results: Torsemide significantly reduced blood pressure 1 h after administration, but this was not seen with furosemide. Fractional shortening, LVIDd and SEP decreased following both treatments, but there were no significant differences between the treatment groups. Torsemide increased heart rate above that seen in the furosemide groups.

Conclusions: The results of this study indicate that 1 h after administration, torsemide increases heart rate and decreases blood pressure when compared to furosemide, but both drugs have similar effects on measured cardiovascular indices.