well, i would build them a secure run. Chickens left in the coop ALL the time will be not very healthy or happy, though you don't want them to get eaten. When we had a killer dog (before i trained her and when i only had a few birds) i built a 15x10 run that was fully secured (wire dug 2 feet into ground, 6 ft tall wire fence along with a wire covered top. Not even coon got into there. If you are on a budget, you could also just build them a run fence so the dog couldn't get in, and close them up at night so the predators can't eat em.I have another question should I leave the chickens in the coop because I have a dog that kills anything on sight (except any thing bigger than her)
If the dog isn't outside all the time, and you have a fenced yard or something, you could let them out for a few hours (i usually did around 3-5) keeping the dog inside to give them some exercise, them put them away when you let the dog back out.