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In this study, young German warmblood horses from foals to three-year-olds were examined by tissue Doppler echocardiography for the first time. The aim of this study was to evaluate the influence of age and growth on the development of echocardio-graphic parameters in order to establish reference values for different age groups. Besides age, weight, height, and sex as well as heart rate were tested as possible variables of influence. A total number of 57 warmblood horses from the age of three weeks to three years was examined, which was divided into 4 age groups (foals, yearlings, two-year-olds and three-year-olds). After the standard 2DE- and M-mode echocardiographic examination, three consecutive heart cycles in the short axis view were stored in Colour Tissue Doppler mode and Spectral Tissue Doppler mode, re-spectively. Out of these data, the systolic, early-diastolic and late-diastolic myocardial velocities in the left free ventricular wall, the interventricular septum and the right ven-tricular wall as well as the isovolumetric contraction in the left free ventricular wall were determined. The heart rate of the foals was significantly higher than the heart frequency of the other groups (P=0.000). The early-diastolic and late-diastolic myo-cardial velocities in the left free ventricular wall measured by Colour Tissue Doppler increased from foals to three-year-olds. In the interventricular septum the systolic and early-diastolic myocardial velocity showed a tendency to increase. In the right ven-tricular wall, only the early-diastolic myocardial velocity slightly increased. Heart fre-quency and height had major impact on the development of the myocardial velocities. Similarly, the early-diastolic and late-diastolic myocardial velocity measured by Spec-tral Tissue Doppler increased from foals to the young adult horses as detected with Colour Tissue Doppler. Furthermore, the early-diastolic myocardial velocity in the right ventricular wall showed the tendency to increase. Heart rate and weight had major impact on these parameters measured by spectral tissue Doppler. Eventually, our results indicate that the growth of the horse overall has a great impact on the pa-rameter value and consequently age also has a notable impact. The partially great impact of the heart rate must be taken into account when evaluating the data. Due to the difficult acquisition of data in young foals and horses it is recommended to sedate the horses to achieve low data variability. Following studies have to evaluate the im-pact of sedation on the echocardiographic parameters in foals and young horses.