The cardiac biomarker canine NT-proBNP indicates cardiac load in terms of myocardial wall stress. The aim of the study was to compare the results of NT-proBNP measurements in healthy dogs and dogs with dyspnea, as well as asymptomatic dogs with heart murmur with the literature.
Material and methods:
Dogs with dyspnea of non-cardiac origin (n=11), dogs with dyspnea of cardiac origin (n=18) and asymptomatic dogs with a heart murmur (n=22) were included between April 2007 and December 2007. Twelve clinically healthy dogs served as the control group. All animals underwent a cardiology examination including echocardiography and measurement of the serum NT-proBNP concentration. The serum was centrifuged and frozen for 30 minutes and stored frozen until analysis.
The median concentration of NT-proBNP in healthy dogs was 240 pmol/l (range 131-546 pmol/l). Dogs with dyspnea and primarily respiratory disease had a median NT-proBNP concentration of 876 pmol/L (range 97-2614 pmol/L). In patients with dyspnea of non-cardiac origin, there was a difference in the NT-proBNP values of dogs with and without pulmonary hypertension diagnosed by echocardiography.
Dogs with dyspnea of cardiac origin had a median NT-proBNP concentration of 2000 pmol/L (range 137-2614 pmol/L). Low normal values of NT-proBNP were only found in patients with pericardial effusion. The median NT-proBNP concentration in asymptomatic dogs with a heart murmur was 698.5 pmol/L (range 121-2614 pmol/L). Considerably elevated values were measured in particular in asymptomatic patients with severe congenital heart disease.
Conclusion and clinical relevance:
NT-proBNP represents a useful additional diagnostic parameter in clinical veterinary cardiology to assess the severity of the cardiac disease. Interpretation should take into account the clinical picture of the patient, as dogs with severe arrhythmias, sepsis, and pulmonary thromboembolism may show elevated NT-proBNP levels without congestive heart failure. Our results indicate the following cut-off values: <500 pmol/l: without relevant cardiac load; 500-900 pmol/l: moderate cardiac load; >900 pmol/l: severe cardiac load.