ArkRescue
Adopt me please !
He should contact the police and the news channels. If it's on TV it may make it harder for this person to sell the dog locally if that was the intent. Also, like the story above, maybe the dog would be returned if they saw it belonged to an older disabled man that was heartbroken. At least if someone saw the dog out with someone else it may ring a bell.
Also if a reward was offered for the dog's return, I'd be willing to chip in if needed to get his dog back for him.