Our two labs tag-teamed a chicken that escaped out of the run when I was going in. We had owned the dogs for 5 years with no problems. I will tell you that while they were on top of her, I was punching and kicking the dogs as hard as I could. I will never forget the look of the almost dead hen after I was able to pull the dogs off. Since then, we moved the coop to the backyard, and the dogs are never allowed outside if I am going anywhere near the coop. I does not matter the breed of dog, they still all come from a wild background. You should not blame a dog for doing what is ingrained in their DNA, just work your hardest to prevent it.