My yard was fenced in and I had several large chow mixes and a chow. I used to find snakes ripped into all the time. Big 5 to 6 ft chicken snakes and black snakes, shredded.
I've had two chows over the years. Most laid back dogs I've ever had, until someone comes around. Never tried to bite anyone, but they would stay between my wife or son and the "intruder". If you wanted to play with one, they would just give me a look like, would you just leave me alone.
My wife would like another one, but the price of puppies is outrageous. Have to stick with my lab.