We’ve all seen the horse that enters into a new situation, whole body on alert, each muscle taut with intense focus on his surroundings. He might poop frequently in nervous anticipation. He might swish his tail or toss his head. Other horses might vocalize repeatedly or move constantly, reluctant to stand still. Such signs of acute stress are often transitory, with the horse settling down after investigating and accepting new environmental information. But what happens in a horse that is continually stressed?