Clinical implications of measurement of plasma atrial natriuretic peptide concentration in dogs with spontaneous heart disease

OBJECTIVE: To determine whether measurement of plasma atrial natriuretic peptide (ANP) concentration could be used to identify heart disease in dogs and to assess disease severity in affected dogs. DESIGN: Cross-sectional study. ANIMALS: 37 healthy dogs and 78 dogs with heart disease. PROCEDURES: Dogs were divided into 5 groups on the basis of plasma ANP concentration: healthy, ANP-1 (< 50 pg/mL; n = 19), ANP-2 (50 to 100 pg/mL; 24), ANP-3 (101 to 200 pg/mL; 20), and ANP-4 (> 200 pg/mL; 15). All dogs underwent physical examination, echocardiography, thoracic radiography, and blood sampling before treatment. RESULTS: Compared with healthy dogs, dogs with increased plasma ANP concentration had significant concomitant increases in heart rate, cardiothoracic ratio, vertebral heart score, fractional shortening, ratio of left atrial-to-aortic root diameter, and mitral early diastolic flow (E wave) velocity and a significant decrease in relative wall thickness. Use of plasma ANP concentration > 25 pg/mL to identify dogs with heart disease (International Small Animal Cardiac Health Council class > I) had a sensitivity of 91.0% and specificity of 94.7%. Use of plasma ANP concentration > 100 pg/mL to identify dogs with International Small Animal Cardiac Health Council class IIIb heart disease had a sensitivity of 81.0% and specificity of 81.1 %. CONCLUSIONS AND CLINICAL RELEVANCE: Results may provide reference values for plasma ANP concentration in dogs and suggest that plasma ANP concentration may help to distinguish dogs with cardiac disease from clinically normal dogs. Measurement of plasma ANP concentration may be a useful marker for predicting the severity of heart disease in dogs.