Rascal at the age of seven had a bout with FCE and was completely incontinent and lacked any bowel control. He rebounded as far as mobility and was happy and healthy for 5+ years afterwards. It required lots of extra work on my part but I would do it all over again in a heartbeat to have soem more time with him.
Bounty came as a broken hock dog. His problem, not necessarily special needs, but his front toes started to fuse. He still got around okay but you could tell they bothered him as well as the toe on his bad leg that had been broken twice.