The 2x4 around the perimeter does not allow a dog to use it's nose as a wedge like under a regular fence, where he digs a little and wedges the fence up a little. Also he cannot pick this coop up with his nose. He will have to dig his entire body depth and length to get in. At night when fox and raccoons are out, the chickens are up in the elevated decks and roost and the predators cannot hear or see them. We check our coops each day for digging, or signs of attempted entrance and take appropriate action when needed.