Motor laterality, such as left or right-handedness, is a well-known asymmetric phenomenon in both humans and animals, incl. horses. Concurrently, lameness caused by orthopaedic injury is a common cause for asymmetry. In our study of riding horses in training, 73 % had motion asymmetries, warranting the question whether this asymmetry was caused by natural laterality or pain-induced lameness? Subsequently, two studies have been initiated to follow young riding horses and trotters possible gait alterations over time. Upon recruitment of the first 50 untrained young horses, 70 % showed motion asymmetries. As young horses may suffer from developmental disorders causing lameness, we still don´t know if these asymmetries are congenital or caused by lameness. We are missing important knowledge about foals. Therefore, we suggest a unique study to compare motion pattern and the relation between motion asymmetries and laterality in foals, young horses in training and high performing horses.