How do you handle a horse that performs differently at shows than it does at home?

A horse that changes significantly at shows is telling you it has not been sufficiently exposed to the conditions that competitions create. This is one of the most common problems for horses that are trained primarily at home in a controlled environment. The solution is more exposure, not more drilling on maneuvers. The warm-up pen at a show is one of the most disorienting places for a horse that has rarely been in one. Horses moving in multiple directions, riders cutting across each other, unfamiliar animals in close proximity — none of that resembles a quiet home arena. If your horse has never practiced in that kind of environment, its ability to focus on you will drop sharply regardless of how solid the training is at home. Incremental exposure is the most effective approach. Haul to busy outside facilities. Ride in group lessons or clinics with multiple horses. Enter lower-stakes events where performing well is secondary to giving the horse a chance to look around, process the environment, and settle. Do this repeatedly until the horse treats a show environment the same way it treats home. For horses that become physically tense and hard in a show environment, extra time in the warm-up to simply walk, stretch, and relax before asking for anything is often more productive than drilling maneuvers in an effort to get the horse focused. A tense horse cannot perform correctly no matter how well it knows the job at home. Relaxation comes before performance.