Yes, dogs can certainly be a problem. I don't have that issue because I have donkeys in the pastures where the chickens roam. No dog, fox, coyote, etc., stands a chance against them, especially since both my jennies are in foal. Add to that my own dogs, who won't tolerate any interlopers and who are "chicken friendly," and my birds are pretty safe from canine predation during the day. They're locked up tight in their coop and pen before I stable the equines and bring the dogs in at night. My biggest risk comes from night predators like coons and opossums, so my pen/coop is secured against them. During the day, hawks are a concern, so I don't free range my bantams. For my standard free range flock, I have plenty of trees and bushes, plus we have placed 30 and 55 gallon drum halves with pop holes in them strategically in the open pastures (secured against wind to fence posts). The only issue with this is you have to leave the hens in a bit later in the a.m. so they'll lay in the nests, and I still occasionally have one decide the drums are more attractive. It doesn't bother me because I walk the fence lines every day anyway. The chickens are pretty aware of their "bolt holes," and the roos do a good job as look outs. Still, I do occasionally lose a bird to hawks, but I personally feel it's worth the risk to let the chickens have run of the place. In the end, it is a personal call for each of us, and I admit there are some of my birds I simply can't bring myself to free range ... my Dutch bantams, for example (one of them is sitting on my shoulder watching me type right now). The birds I free range do seem to be happier for it (or else I'm simply anthropomorphizing them again to make myself feel better ... who knows?!)