I have two mutts of unknown origin who are fine with the chickens. One looks a lot like a black lab but has a chow tail. The other looks like a cross between a cocker spaniel and a chihuahua, probably with some dachsund thrown in. My son's dogs also roam among the chickens without a problem, one is a pure black lab, the other some cocker sized black and white shorthaired thing. All know what no and leave it mean, and they ignore the chickens. Two hunt and kill mice and rats, and another will kill strange cats, buts leaves mine alone. The fourth barks at but runs away from everything.