Tricuspid valve dysplasia in a horse: Clinical and pathological findings

Tricuspid valve dysplasia is an uncommon cardiac congenital defect in the horse. Previous scientific reports concerning this cardiopathy describe only two cases, wherein the valvular abnormality was associated to other congenital cardiac defects. Herein are reported clinical and pathological findings of 13-year-old male horse examined because of poor performances. Physical examination demonstrated signs of right-sided congestive heart failure. Electrocardiogram showed atrial fibrillation. Echocardiography revealed severe right-side heart enlargement with a hypomobile small septal leaflet of the tricuspid valve, partially adherent to the myocardium, resulting in incomplete closure of the valve during ventricular systole. Necropsy findings confirmed right-side cardiac enlargement and tricuspidal septal leaflet adhesion to the myocardium, with mild ventricular displacement of the valvular origin. To the authors' knowledge this is the first report about isolated tricuspid valve dysplasia in horses. The description of this case is useful, as this rare pathology should be borne in mind, when approaching the differential diagnosis of cardio-circulatory diseases in horses.