Ash;3849142; said:DO NOT PUT THE PICTURE/DESCRIPTION UP IN ANY FLIRES ..... I cant make that anymore clear....
Dog theives will snatch it up giving you the discription of the dog off the picture. It is something that is actually very common and very sad.
Post up a lost dog flier but do not put up a picture or description. Just put a flier up stating that you found a lost dog and a number asking them to call with a description and if they can match the description to the dog you found. (like color of dog, it has that anit-flea color, its regular color is red, etc. ). If they can't then don't even bother letting them see the dog.
If no one claims the dog then put it up for adoption (maybe with a small fee, usually people who get things for free dont tend to care for it as much as they would if they paid for it....) that is really up to you, just try to find it a good home without having to take it to the shelter. I am not sure but you can run by a vets office and usually (if they are nice) they will scan for a chip for free also.

Have him scanned for chips. IMO if you were able to get him in your garage and you are still in one piece he was probably a pet at some point. If no one comes foreward, try to find a good no-kill shelter or a rescue farm that can take him.