You did the right thing!! How cruel can some people be to these dogs!! Having them chained up is the worst thing you can do to them.
So I guess the animal control will come and take him/her to a shelter. I'm not sure how this works and you may have to call the same animal control or the shelters around you to see how it works. I'm sure they'll be happy to hear from a considerate person because a lot of these dogs get put to sleep for lack of space available or if they have aggression issues!! I volunteered at the SPCA a while back and they had green collars on dogs who were adoptable and I used to take them out to walk them and play with them. There was a back area where you usually heard dogs bark and they had red tags on which meant they were aggressive and were going to be given an agression test. If they passed the test they were given a green tag, if not they were put to sleep
I couldn't even look at them knowing their possible fate!! To me they were all cute beings in need of a loving home!!
So please call around and make an effort and maybe you'll be able to get a hold of him. Although there is a minimal adoption fee if he ends up at the SPCA. Please keep us updated too!!