I hate to sound unduly harsh, but it's based on experience losing a lot of chickens over the years to dogs. Dogs and chickens do not mix. I'm not even sure I would totally trust a well-trained LGD around chickens. As others have pointed out, dogs don't kill the chickens to eat them, it is more for sport. If I come out and see a pile of feathers where a chicken used to be, it's probably a fox, but if I come out and have 10 dead, gnawed up chickens scattered around, that is a dog, guaranteed. We go through cycles out here where we get stray dogs and that is a big problem. Early on, I would chase them off the property but found out the hard way that they would just keep coming back repeatedly until they got to the chickens. I ended up being a whole lot less sympathetic after the number of dead chickens piled up and now unless I specifically recognize the dog, I usually end up shooting it if it is on our property threatening the livestock. I hate to do it, but I have found there is really no other effective way to deal with the situation. As I say, you become a whole lot less sympathetic when you lose 10-12 chickens at a time, or, even worse, when you have a chicken that is so gnawed up that you have to kill it to put it out of its misery. For the record, I don't think I have ever lost a chick to a dog, though - it is always full-grown chickens. When it is your own dog, it may actually be tougher, but you just need to keep the chickens locked down really well and don't trust the dog around the chickens no matter what.