Torsemide is a novel diuretic that promotes renal excretion of sodium, chloride, and water by targeting the thick ascending loop of Henle, similar to furosemide. It also confers an anti-aldosterone effect, similar to spironolactone (potassium-sparing diuretic), which may reduce diuretic resistance and myocardial fibrosis. Compared to furosemide, torsemide demonstrates 10 times greater diuretic potency and approximately double the duration of action in dogs and cats.1 Furthermore, torsemide may exhibit greater bioavailability and a higher ceiling effect than furosemide. This can result in a stronger, more sustained, and uniform diuretic profile and has been shown to be effective in dogs with advanced congestive heart failure.2
In a MedVet study of cats with advanced CHF and inadequate heart failure control with furosemide, a switch from furosemide to torsemide led to extension of congestive heart failure control.3 Careful monitoring of kidney values and electrolytes is warranted, as some patients may require adjustment in torsemide dosing. Additional study of torsemide use earlier in the course of CHF therapy in comparison to furosemide is still needed. Presently, torsemide is primarily used for challenging heart failure cases, and any decision to start torsemide must critically account for a patient’s hydration status, kidney and liver function, and trajectory of heart failure control.