How do you identify and correct a horse that leans on the bit?

A horse that leans on the bit — maintains constant downward or forward pressure against the rein — is a horse that has learned to use the rider's hands as a balance point rather than maintaining its own balance. Clinton Anderson identifies this as one of the most common and most correctable bit problems, and his diagnosis points consistently at the rider's hands as the origin. Leaning on the bit develops when a rider maintains constant contact that never releases — the horse pushes against the rein, the rider pushes back, and over time the horse learns to use that steady resistance as a fifth leg. The horse that leans has been trained to lean by a rider who provided something to lean against. Anderson's correction removes what the horse is leaning against. Rather than maintaining steady contact against the horse's leaning pressure, he teaches releasing the contact completely and immediately when the horse leans — dropping the rein so the horse has nothing to push against and must find its own balance. The horse that expects contact and does not find it will typically stumble slightly or reorganize its balance, and over repetitions learns that leaning forward finds no resistance — which removes the motivation for leaning. Warwick Schiller frames this as a nervous system issue as well as a training one — some horses lean because they are anxious and using the contact as a grounding sensation, not because they are dominant or lazy. For these horses, removing all contact suddenly can increase anxiety. His approach is to gradually reduce contact while maintaining enough connection that the horse does not feel abandoned, coaching the horse toward self-carriage incrementally rather than through an abrupt withdrawal of the contact it depends on. Parelli's Porcupine Game done under saddle — applying light steady rein pressure and releasing the instant the horse gives — directly addresses leaning by teaching the horse that giving to pressure produces immediate release, which rewards lightness rather than heaviness against the bit.