As others have said, your best bet is to build an enclosed run. Our coop is in an enclosed run, but we also free range, and we've got fox, skunks, bears, opossum, weasels, and plenty of birds of prey to supplement the free-roaming neighborhood cats and dogs. The cats have pretty much made friends with and hang out with the chickens and the dogs are a greater problem than any of the wildlife, so far (and we've seen plenty of day-roaming fox), BUT we only free range when my DH and I are home. When we're not around or engaged in something we can't readily run away from indoors, they stay locked in the run. In overnight hours, they're locked in the coop in the locked run.