you can out on a wire on the inside part of the fence (called electric fence) and there will be electricity running through it and your horse will be zapped when she touches the wood with her nose. It doesn’t hurt them, it releases right away-soon the will learn that the fence is not to be touched here. or it could be that she needs some vitamins and/or minerals- something might be bugging her. Or it could be boredom. Try a LickIt or a ball to roll in the pasture and to play with.