Everything loves a chicken dinner. Unless you live in a city where the predator population has already been driven out, you are faced with the decision to either let them free roam (and accept a small but steady rate of predation) or keep them penned when not under direct supervision. There's not a third option.
We had racoons, skunks, and foxes paying nightly visits. Occasionally one would find a way into the coop and there would be a massive kill off. We got a dog, and just the scent of the dog around the coop has been enough to eliminate the skunks and racoons anyway. The fox still does come by from time to time. We had to put a net over the roof of the coop because of hawks.
Our coop is impenetrable; we never lost any chickens that way. But they would get picked off during the day by hawks, coyotes, and bobcats. One every month or two.
We've given up and are switching to bantams in an enclosed run.
Based solely on what I've read and experience with them when I'm on a bicycle...
Not really, because you want to dog to be bonded to the livestock, not the humans. The dog lives outside amongst the other farm animals. They tend to be more territorial and protective than pet dogs. All that said, I've seen them used more with sheep than poultry.
