It looks like old frostbite, but even if it is not- the end result is he has dead toes and some of his foot looks necrotic (dead) as well. I suppose it could be circulatory or some weird infection- but the end result is still dead toes & some of the foot. Giving him antibiotics and vitamins with not bring the tissue back to life. This tissue will eventually fall off. He won't do well long term walking on stumps. I think you need to humanely dispatch him. You are hoping he will die in the night to end his suffering? If you cannot do this yourself, you need to find someone who can. He may struggle on for days/weeks/months- walking on his painful feet- do him a kindness and dispatch him. Looking at the previous posts- this has been going on for months----I am sorry this is harsh, but I think it needs to be said & done.
