My dogs are great with the chickens, with some good verbal control I can call them back to me if necessary. The chickens run around the dogs, the dogs ignore them. The dogs sleep on the grass the chickens are all around them, they shared the back yard so well. I was so proud of my dogs, who had never been around birds of any type. They were great. Until they killed one. I came out (I thought I was within earshot of the dogs and chickens, but I was distracted) and one of my barred rocks had been "played" with to death. I think every bone in her body was broken, so I'm sure she was shaken. I began watching the dogs very carefully, but they were so good. Then I finally figured out how it happened when I saw that the chickens would randomly fly up onto the dog run fence, then fly down screaming/squawking/flapping and then they started running. They were too much like prey in that one instance and my dogs started chasing the one that did it. I called the dogs to me, and they came right away. Then it happened again when one of the chickens got a sticky fly trap stuck on her (screaming/flailing behavior). Again I stopped the dogs. But for months in between each event everything was great. The dogs never chased the chickens, they were gentle around them (no wild play when the chickens were around), etc. Then I found my other barred rock alive, but with the skin of her head and neck removed. The dogs did it. It was in good fun for them. They aren't out to massacre my chickens. But since then I have portable fencing I put up to keep dogs and chickens separate. It isn't worth the heartbreak.
I guess my moral is that some dogs can handle it, but remember that when mixing predators (dogs) with prey (chickens), accidents happen. It is not the dogs fault really, it is ours for putting them in that situation. Training is really important, but you should always be there when the dogs and chickens are together if you want to guarantee safety.
