Jax, How is he Alive?

Johnny, Jax and I are on the roof winterizing the air coolers for the snow that is to come Wednesday night or Thursday. Suddenly Jax takes off running from one end of the roof shoots right by me before I can say anything and leaps off the west side of the lodge. I hear him hit and cry out twice. I look over the side and he's standing up but crying. I run down the ladder and get to him and for the last couple hours I've been watching him but he appears to be fine. He's crazy.