If someone left him at the store, my concern would be that he might try to go back there. I would think he was dumped since he needs care and has a new collar though. I put papers down in the garage at night for Cindy. She won't go but will hold it until she can get outside or for some reason, by the door of my back bedroom.
Heh.... They'll try to hold it. I don't have a garage... but the barn is dry and I may put him out there with some bedding.