Cribbing is a habit in which the horse forcefully swallows gulps of air. Usually the horse grasps at an object with its incisor teeth, then pulls its neck back in rigid fashion as it swallows air. The condition is considered a habit of boredom but is dangerous to horses because the swallowed air can create gastric upsets or colic. In addition, chronic cribbers can wear down their upper incisors. Cribbing should not be confused with wood chewing.