I think most people, including myself think jumping for dogs is natural but as with humans they can get sprained muscles or worse if they land wrong. I built a carpeted ramp for our dogs to get in the back of the high F-350 but they always jumped out. When our newly adopted 90+ # Rotti jumped down I saw her flinch and she had a slight limp on her front leg for a few days. Now they "stay" until I set the ramp and they all now walk down. It was lucky I saw her flinch so I learned not to allow anymore jumping .... :)