Lightning fast? Absolutely. The Belgian Shepherd Dog, also known as the Belgian Sheepdog or the Chien de Berger Belge, is a Belgian breed of herding dog of medium size. The chest is deep but not overly broad; the neck is muscular, widening at the shoulders with a slight arch at the nape. The tail is strong and of medium length, and curves upwards slightly at the level of the knee. The forelegs are straight and well-boned, the hind legs muscular and powerful; the legs are not overly heavy. When in motion, they can swiftly change direction at full speed. Their exuberance and protective instincts often lead them to move in circles.