We have a dachshund that developed sudden rear end paralysis when he was seven. We had the diagnostics, surgery, and physical therapy done. The surgery was not successful but physical therapy did result in spinal walking. That said I would probably not put a twelve year old dog through the surgery and possibly not even the physical therapy regardless of financial considerations. Our dog was very athletic and he seemed to enjoy the physical therapy but he probably wouldn't like it nearly as much now that he is older. An older dog would probably get rather sore especially if previously sedentary and they would not understand the potential benefit. Also, our dog is now fifteen and seems to be going downhill. I doubt that we will have him much longer.