yes when he is alert he tends to get straight rear legs which sometimes concerns me..also when he walks slowly he has a swaying rear end... the vet says he is just a big boy ......but it disappears as he moves a bit quicker. despite his weight and his rapid growth he never showed any lameness, he is very fast and agile. he seems lazy but when he wants to play and he is motivated he is tireless and a very very fast runner.