Measurement of plasma endothelin-1 concentration in healthy horses and horses with cardiac disease during rest and after exercise.

Cardiac biomarkers are important tools for monitoring disease progress and can monitor progression of therapy. Endothelin-1 (ET-1) has been studied for its use as a cardiac biomarker in human and small animal medicine while in horses with cardiac disease it has not been evaluated yet. The objective of the present study was to determine the concentration of plasma ET-1 in healthy horses and compare it with ET-1 concentration in horses with cardiac disease during rest and after exercise. Fifty four horses admitted to the Equine Clinic of Free University of Berlin were used in the present study, of which 15 horses were clinically healthy with no evidence of cardiac disease (Group 1), 22 horses suffered from cardiac disease with normal heart dimensions (Group 2) and 17 horses with cardiac disease and enlarged heart diameters (Group 3). Clinical examination, electrocardiography and echocardiography were performed. Endothelin-1 concentration was determined using ET-1 ELISA kit. The concentration of plasma ET-1 was significantly increased in horses with cardiac disease and normal cardiac dimensions (Group 2) and in horses with cardiac disease and enlargement of the left atrium (Group 3) compared to its concentration in clinically healthy horses (Group 1). In addition, the concentration of plasma ET-1 after exercise was significantly increased in diseased horses compared to its concentration at rest. Detection of ET-1 plasma concentration in horses at rest may be useful for detecting horses with changes in left atrial cardiac dimensions.