Pugger I would have done the same as you. Our cat Heman, came to us in similar circumstances. He showed up at our door, tiny, skinny and flea-ridden, he wouldn't have been older than 5 weeks. Flyers, door-knocking, newspaper, no-one claimed him. We didn't want to take him to the pound as he would have been dead in a week (not exaggerating). Oh and he was very, very friendly and picked up house-training very quickly. Which makes us think that he and his possible litter-mates were dumped. If there was an owner they didn't make any effort to find him, anyway. He's now a 7kg ball of fluff and love.