My dachshund is about 8 years old and was doing just great. On Sunday afternoon I noticed he was moving slow. I looked at him closely and his back hips were smaller than normal. This came on real quick. I've had a German Shepherd that lost her back hips but it was over a long length of time. My little dog seem to happen over night. He is still eating but does not want to walk around just lay in his bed. What can I do?