I went out to check on the chickens today and saw these prints. I didn't go out yesterday so I'm not sure how long they have been there. Whatever it was couldn't get in the coop (and there is no evidence of it trying--like scratches on the coop or anything) but was able to get in the run. We have a 5 foot hardware cloth fence around it, nothing dug under (it's been well below freezing for at least a week) and I guess it could have squeezed in through the gate? I don't know. Any guesses? There is a very large "polar bear" dog as my kids call it, that is out all the time in an unfenced yard. In my uneducated opinion it looks like a Great Pyrenees, but I really don't know. The only other dog that I know gets out sometimes is a small scotty dog. We don't have a fence and live fairly rurally, a 1/2 acre lot in a new development in the foothills.