Establishment of reference values for echocardiographic parameters of trained and untrained Icelandic horses

The aim of this study was to establish echocardiographic reference values for healthy Icelandic horses. For this purpose cardiologic examinations were performed on 44 healthy trained and untrained Icelandic horses without known cardiologic or pulmonary disease. The atrial diameter of the trained horses were significantly greater than in the untrained horses and the left ventricular free wall diameter was also higher in the trained than in the untrained horses. These findings confirm that the changes of the heart caused by training which have previously been described by other authors in warmbloods, thoroughbreds, dogs and humans are present in Icelandic horses as well. However, in contrast to the findings in race horses, no enlargement of the left ventricle was found in trained Icelandic horses, which may indicate that training conditions of Icelandic horses are not comparable to those of race- or jumping-horses in high level training. The reference values established in this study will serve as basis for the current interpretation of the results of echocardiographic examinations in Icelandic horses. This should enable cardiologists to perform a more detailed and precise examination similar to cardiological examinations in warmbloods and race horses.