I would just take them to your local pound. IF the owners find them, they will still have to pay the fee to get them back out. When you drop them off, make sure to tell the shelter people that you tried to give the dogs back several times AFTER they killed your pet chickens and the owners did nothing. Chances are the owners aren't going to look for them. But if they do, then I'd catch them again and take them a few counties away if you can (around here, if you don't live in a county you can't leave animals in the shelter... you have to take them to your county, no matter how far away you found the animal) Or just find them new homes.