I think in order for an animal to feel regret, they must know right from wrong. Does the wild Bear feel regret for mauling a hiker? No...but a pet dog I think feels regret when they tear up your favorite shoe. They knew they were not supposed to and realize how disappointed you are in them, so they feel regret, not for destroying teh shoe per se, but for letting it's owner (see parent) down. Any pet really...wild animals, not so much.