Why does my horse do obstacles at home but not at a show?

A horse that handles obstacles correctly at home but fails to do so at a show is not demonstrating a trained skill that has disappeared — it is demonstrating that the training was confirmed in one specific environment and has not been generalized to the range of environments that competition presents. The show environment introduces multiple simultaneous changes from the horse's home experience: new arenas with different footing, dimensions, and visual characteristics; the presence of many unfamiliar horses in close proximity; crowd noise, announcements, and the general heightened activity level of a show; banners, sponsor signs, flags, and decorative elements that may not be present at home; the rider's own elevated nerves that communicate through the seat and hands; and the specific obstacle designs used in the competition course that may differ from what was practiced at home. Any one of those variables might be within the horse's current ability to manage; the combination of all of them simultaneously may exceed the total emotional capacity the horse has available for obstacle work. The horse that refuses a bridge at a show that it crosses easily at home may not be refusing the bridge — it may be overwhelmed by the accumulated stress of all the new variables and the bridge is simply the point where its capacity runs out. The training solution is not to drill the bridge harder at home but to expand the horse's comfort zone through varied environmental exposure: hauling to different locations for schooling sessions, practicing obstacles near the warm-up activity of other shows before entering competition, and exposing the horse to the specific types of environmental stimulation that shows present. Each new environment experienced in low-stakes conditions builds the broader confidence that eventually allows the horse to access its training at a show the same way it does at home.