The same thing happened to me. I put nails in the walls and had my grow partner hold up the snapped portion while I tied pieces of floss from the top of the stalk to the walls. I tied it in 3 directions for full support. The injury healed suprisingly fast, and all parts of the plant are still producing.

Oh, and I suggest keeping the dog out of the grow room. Other than snapping plants in half, they can introduce all kinds of nasty bugs to your plants.

Good luck friend.