Atrial Natriuretic Peptide as an Indicator of the Severity of Valvular Regurgitation and Heart Failure in Horses

Natriuretic peptides are cardiac biomarkers, routinely used for diagnosis, prognosis, and guidance for treatment in human and small animal cardiology. However, their diagnostic and prognostic value in horses has received little study. The aim of this study was to investigate the plasma atrial natriuretic concentration (ANPPl) in a large group of horses with various degrees of valvular regurgitation (VR) and congestive heart failure (CHF). Clinical examination and two-dimensional time-motion mode and Doppler echocardiography were performed on 91 horses admitted to the Equine Teaching Hospital of Liege University, with either no, mild, moderate, or severe VR and presenting various stages of CHF. Plasma atrial natriuretic concentration was measured using a commercially available human radioimmunoassay test. Mean values of body weight, age, ANPPl, and echocardiographic parameters were compared among horses with no, mild, moderate, and severe VR and among horses in different CHF stages. Correlation and linear regression of ANPPl with each echocardiographic parameter and with the percentage of dilation of each of cardiac chambers were assessed. Horses with severe or moderate VR had significantly higher ANPPl than those with mild or no VR. Plasma atrial natriuretic concentration was significantly higher in horses presenting CHF than those without CHF. Plasma atrial natriuretic concentration was significantly correlated with the left atrial diameter and its percentage of dilation. These results suggest a diagnostic value of ANPPl in horses with VR, especially with tricuspid or mitral insufficiency with dilation of the atria.