wow, he is gorgeous!! you're so nice to take care of the poor guy. It sounds like he isn't too horribly injured, but maybe try spending time whenever you can sitting out near where he is, and you might be able to gain his trust and get him some medical attention? I'm sure that if you were able to take him to the vet a rescue group or the SPCA would pay for it.
Maybe you could build/buy him a dog house where you usually see him so he can have some shelter?
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