Please do not feel any guilt in Duke's treatment....My sister's wonderful Golden had cancer which had spread before he showed any signs of illness. She kept questioning "what if? I had caught it sooner...." well, the prognosis would have been the same......just love him with all of your heart and make this time with him the best. He lives one day, one moment at a time.....just love him!! You will know what to do which is in his best interest. God Bless you!