Retrospective review of the use of hydrochlorothiazide in dogs with myxomatous mitral valve disease and refractory congestive heart failure (American College of Veterinary Cardiology stage D)

Abstract

Introduction/objectives: In dogs with myxomatous mitral valve disease (MMVD) American College of Veterinary Internal Medicine (ACVIM) stage D, hydrochlorothiazide (HCTZ) can be added to achieve sequential nephron blockade. Information on outcome, survival, and complications in this group of patients receiving HCTZ is limited, hence the aim of the present retrospective observational, longitudinal study. Animals, materials and methods: A single-referral-center cohort study was conducted; 25 dogs diagnosed with MMVD stage D receiving HCTZ as part of multimodal treatment of refractory congestive heart failure were included in the study. Data retrieved included cardiac treatment at T0 (when HCTZ was first prescribed) and subsequent visits, available bloodwork, echocardiographic assessment, additional diagnostics, cause of death, and survival time. Results: Mean starting dose of HCTZ was 0.8 mg/kg every 48 h, with progressive increases (latest mean recorded HCTZ dose: 1.5 mg/kg/day). Azotemia was identified in three dogs at T0 and in 11 dogs following HCTZ addition. Three dogs experienced clinically relevant side effects, resulting in discontinuation of HCTZ in one dog. Twenty dogs died, the majority due to cardiac disease (90). Median survival time of the cohort was 268 days. Study limitations: Limitations of this study included the retrospective nature of the study and small sample size. Conclusions: Although associated with an increase in renal parameters, HCTZ addition at the study dosages appeared clinically tolerated in most dogs with MMVD ACVIM stage D, with a prolonged median survival time for dogs in ACVIM stage D