Torasemid im Vergleich zu Furosemid zur Therapie der chronischen Herzerkrankung bei der Katze

Torasemide compared to furosemide in the therapy of feline chronic heart disease

Loop diuretics are a cornerstone in the therapy of congestive heart failure. Their primary use is the removal of acute lung edema as well as other fluid accumulations due to heart insufficiency. The need for regular and reliable drug administration poses a challenge in many feline patients and can be a limiting factor for successful treatment.
The advantage of the loop diuretic torasemide compared to the commonly used furosemide lies in its once daily administration. The comparable efficacy and safety of torasemide in humans and dogs has already been shown in various studies. So far only a few studies on the clinical use of torasemide in the feline patient exist.
The aim of this study was to evaluate the influence of torasemide on selected clinical, echocardiographic and laboratory parameters in cats with chronic heart disease compared to furosemide. The goal was to show that torasemide could pose a possible new therapy option for cats with heart disease.
The examination results of 40 cats that were treated with furosemide and 38 cats treated with torasemide were analyzed both prospectively as well as retrospectively from patients of the Small Animal Clinic at Freie Universität Berlin between July 2017 and May 2021. Of the cats treated with torasemide, 11 patients already received long-term treatment with furosemide. In addition to the comparison of the 2 loop diuretics, the patients with a switch from furosemide to torasemide were evaluated separately.
In this study population no statistically significant differences were found between patients treated with torasemide compared to those treated with furosemide in regards to the development of the vital parameters under therapy. Comparable results were found for the changes in echocardiographic parameters. Neither the influence on the ratio of left atrium-toaorta (LA:Ao) nor on the measurements of the left ventricle (the thickness of the left ventricular posterior wall and the interventricular septum in diastole, the diastolic inner diameter of the left ventricle as well as the fractional shortening) showed significant differences.
Looking at the laboratory parameters potassium, creatinine and urea also revealed almost no differences between the treatment groups. These findings were confirmed with regards to the systolic blood pressure, the radiological development of lung edema, pleural effusion, and vertebral heart score as well as the tolerance of both loop diuretics.
Patients treated with torasemide suffered from more advanced stages of heart disease in comparison to those treated with furosemide at time of inclusion. Nevertheless, no differences were found between the treatment groups concerning the clinical development under therapy or the survival time.
Cats under treatment with torasemide received significantly lower dosages in relation to those receiving furosemide assuming a dose-effect relationship of both loop diuretics of 1:10. espite these differences the cats treated with torasemide showed similar clinical developments and changes in the evaluated parameters.
In conclusion, no statistically significant differences were found comparing the once daily administration of torasemide to the twice daily administration of furosemide regarding the evaluated parameters in this study. It can be pointed out that the switch to torasemide at more advanced stages of heart disease is easily possible for patients in which the treatment with furosemide is no longer effective. This study was able to confirm torasemide's essential advantage of once daily administration in contrast to the need for repeated administrations of furosemide with comparable efficacy for feline patients.