I very sorry for your lost chickens. I love my dogs but one is a hunt dog with bird dog blood and I worry about her everyday. Today she earned her keep detecting, alerting us to and killing a possum right next to the coop. But I know one day that same dog may make me sad. I put up chain link with hardware cloth at the bottom going up the chain a foot and out on the ground a foot to discourage digging. So far is has worked but don't know for how long.