Always always call in a complaint!! that way there is a record ! I think that talking to the man was very much the right thing to do and if it happens ever again remind them that you can and will take the dog and that the little boy can come see him . Talk to the wife and child about this to that way they know you are only trying to help the dog and not trying to keep it from them. also offer them $20-40 for the dog money talks even that little amount. I had to deal with my neighbors not to long ago about their dogs running loose starving pregnant it was bad . i ended up giving him $50 a dog and found them all(3) wonderful homes where they now live inside and are fixed safe and sound!! The police would not help me at all and this was the only thing i could do to get then out of the mess they were in. I learned later that always call in a complaint so they have a record. GOOD LUCK and keep me posted!