Effect of a specially formulated diet on progression of heart enlargement in dogs with subclinical degenerative mitral valve disease

BACKGROUND: Previous studies in dogs with degenerative mitral valve disease (DMVD) have identified altered myocardial energy metabolism and oxidation, which might contribute to cardiac hypertrophy. Diets rich in medium chain fatty acids and antioxidants are a potential means of treatment. A previous clinical study found significantly smaller left atrial diameter (LAD) and left atrium‐to‐aorta diameter ratio (LA : Ao) in dogs with subclinical DMVD fed a specially formulated diet vs control diet for 6 months. HYPOTHESIS/OBJECTIVES: A specially formulated diet will slow or arrest left heart enlargement in dogs with subclinical DMVD over 365 days. ANIMALS: One hundred twenty‐seven dogs with unmedicated subclinical DMVD; 101 dogs in the per protocol cohort. METHODS: Randomized double‐blinded controlled multicenter clinical trial. RESULTS: The study's primary composite outcome measure was the sum of percentage change in LAD and left ventricular internal dimension at end‐diastole (LVIDd) at day 365. In the per protocol cohort, the outcome measure increased by 8.0% (95% confidence interval [CI], 2.9%‐13.1%) in dogs receiving the test diet vs 8.8% (95% CI, 5.1%‐12.5%) in dogs receiving control diet (P = .79). Neither component of the primary outcome measure was significantly different between groups (LAD, P = .65; LVIDd, P = .92). No difference was found in mitral valve E wave velocity (P = .36) or the proportion of dogs withdrawn from the study because of worsening DMVD and heart enlargement (P = .41). CONCLUSIONS AND CLINICAL IMPORTANCE: Feeding a specially formulated diet for 365 days was not associated with a significantly different rate of change of left heart size in dogs with subclinical DMVD as compared to control.