My yearling has a major stress in his stable while I go out of the yard on a hack or to the school. He has a window which he can poke his head out and his stable door can see down to the edge of the school. He hasn't hurt himself and does calm down sometimes but he makes his stable as mess by the time I come back. I put his treat ball in to keep him amused, he has a full haynet and a jollyball to keep him happy. Is there anything I can do or just let him stress and keep clearing up his mess.