What a tragic sounding life this poor dog has had! You may get a lot more responses by posting this in "Dog General" sad to say. More people frequent the General sections, as opposed to the Rescue. I'm glad you're providing this dog with nourishment, and it sounds to me as though the only way anyone can get help for him, is with a humane trap. How often do you see him? If it's daily, maybe a Humane Officer trained in tranquilizing animals can dart him, and find him/her some help before it's too late. The dog is no doubt very feral by now, and inclined to bite if cornered in any way. Have you contacted shelters in your area, and or posted under dog rescue groups on the internet? Keep us posted..too sad.