Both of my dogs are mutts. The worst offender is a lab, weimaraner, chow, and god knows what. The other is a border collie, aussie, coyote mix. Both are rescues with issues. We do our best with them, but...well we really do try. While the instinct is there for both of them to eat the chickens, I have made them so fearful of them - they do not try. They will tell me when it is time to put them to bed (when I space it) and if something is not right - like an escapee. It took much time to get them to behave, but they did and are fantastic chicken guards now. If the eagles, osprey, or hawks are circling....they now bark like demons. They do look at the babies like it would be a fantastic snack, but shy away when one is near. While your dog is a chicken killer at the moment - with enough "chicken torture"....your dog may become a great protector. I just made it a point to hold the birds, get the dogs close enough, made sure that they knew that the chickens belonged here (wing flapping, loud cackles, pecking, etc - the chickens, not me). I got my point across. Did the same with my 'bird slayer' cats too. I am so sorry about your roo! No matter what the cause of death was....it is hard to loose any chicken baby (full grown or not).