In this study, we excluded dogs with arrhythmia (n = 3), pulmonary hypertension (n = 3), left ventricular outflow tract obstruction (n = 1), patent ductus arteriosus (n = 1), and chronic kidney disease (n = 3) because these diseases could elevate NT-proBNP concentrations. Here, NPPB is linked to pulmonary arterial hypertension.