My GSD is 10 years old, just this past week I've noticed him have a limp after laying down for a while. He isn't over weight, and goes for long walks everyday, he still chases deer and rabbits in the yard. I'm getting worried about hip displagia. Anyone have any ideal or had this problem? I know he is getting old. Up until last year he would jump into the bed of my truck, now he wants to, but just can't do it.