My sisters previous cat would sit on the front step waiting to come in, sometimes all night...and one night a fox was screaming at it three feet from its face, the cat just looked at it...the fox left. There is something in that ancestral dog/cat DNA that puts fear of the other into them, but it is obviously more than that, the unflappable and boldness of creatures impresses just as much on that fight/flight response. I think the dog knew it did bad and knew it would have to run from anything reacting to what it did. Animals aren't stupid, they may make mistakes, but they aren't stupid.