My brother was one of the ones that needed to be kept on a leash, because he would be gone in an instant. We even have pictures of him at home on the dogs runway behind the house. One example, he decided one day to ride his tricycle down the road to the neighbors. This wasn't some housing development street, this was a state highway, 55mph, with a blind turn. He's lucky someone spotted him before hitting him and basically stopped traffic so my mom could get him.