Pathologic right-sided heart changes are a common echocardiographic finding in patients with pulmonary hypertension (PH). Canines with PH may have right heart pathology documented via echocardiographic color Doppler interrogation including tricuspid valve regurgitation, pulmonic valve insufficiency, elevated pulmonary arterial systolic pressure, elevated pulmonary arterial diastolic pressure, and alterations in ejection profiles. Two-dimensional echocardiographic findings may include right ventricular hypertrophy, interventricular septal flattening, paradoxical interventricular septal motion, pulmonary artery dilation, and potentially abnormal left heart dimensions. In veterinary medicine, much confidence is given to the measurement of pulmonary arterial systolic pressure estimated from tricuspid valve regurgitation to grade the severity of PH and monitor its improvement with little emphasis placed on the integration of two-dimensional echocardiographic right and left heart pathology in conjunction with Doppler findings. To the authors' knowledge, marked improvement and/or resolution of echocardiographic-documented right heart pathology have not been previously reported in the veterinary literature. This case report documents profound echocardiographic improvement of right-sided heart disease in a dog with severe PH.