Application of torsemide to two dogs with congestive heart failure

Abstract

: An 11-year-old castrated male Maltese weighing 3.6 kg and a 12-year-old intact female Shih-tzu weighing 6.5 kg were admitted to the Veterinary Medical Teaching Hospital of Chungnam National University with decompensatory congestive heart failure. Diuretic resistance was suspected due to long term diuretic therapy with furosemide. However, the patients improved after the furosemide treatment was changed to torsemide, demonstrating the benefits of application of torsemide to treat diuretic resistance caused by long term use of furosemide. These findings suggest that torsemide should be applied for treatment of diuretic resistance caused by long term use of furosemide.Keywords : congestive heart failure, diuretic resistance, pulmonary edema, torsemideCongestive heart failure (CHF) occurs when the heart is unable to provide sufficient pump action to maintain blood flow around the body [9]. As a result, the retention of fluid in tissue or body cavities can occur [9]. Loop diuretics are essential in the treatment of CHF in human and veterinary patients, because they reduce diastolic intraventricular pressure and capillary pressure, and the clinical signs associated with CHF including pulmonary edema, pleural effusion and ascites [10]. Furosemide and torsemide are loop diuretics commonly used in humans [6]. In contrast with furosemide, torsemide is not commonly used in veterinary medicine currently.The efficacy of torsemide has been previously established in human patients with CHF [2]. According to a recent study in humans, cardiac mortality and hospital re-admission rate are reduced, and functional heart failure class was improved in patients treated with torsemide compared with furosemide or other diuretics [2]. These studies support the use of torsemide in veterinary medicine.Torsemide is effective in patients with pulmonary edema caused by CHF at one-tenth of the furosemide dose [8]. Torsemide has a high bioavailability and a rapid absorption rate, even in patients with chronic renal failure, while the bioavailability and absorption rate of furosemide are reduced pathological states such as CHF [15]. Moreover, torsemide has a longer duration of diuretic action than furosemide, and also functions as an antagonist to aldosterone to competitively inhibit aldosterone-receptor binding in tubular cells [11,12]. Because of this, torsemide, like spironolactone can inhibit myocardial remodeling and improve left ventricular function in CHF [1,5].In this case series, torsemide was used as a replacement for furosemide in the animals with suspected diuretic resistnace.In first case, an 11-year-old castrated male Maltese dog, weighing 3.6 kg with a history of mitral valve insufficiency (MVI) and pulmonary edema, was referred with a chief complaint of cough, and labored breath. The patient had received management for heart failure 5 months previously. On physical examination, a holosystolic murmur (grade 5/6) was auscultated, and increased heart rate (210/min), respiratory rate (120/min) and blood pressure (173 mmHg) ...