How do you ride a horse that leans on the bit in dressage?

A horse that leans on the bit — putting significant weight into the rider's hands rather than carrying itself with self-carriage — is a horse that is using the contact for balance rather than communication, and the correction requires developing the horse's self-carriage rather than managing the heaviness through stronger rein resistance or more restrictive contact. The fundamental approach is to make the support the horse is seeking unavailable while simultaneously developing the physical capacity for self-carriage that allows the horse to support itself. Transitions — particularly frequent, precise transitions both between gaits and within gaits — are the primary corrective exercise because they require the horse to engage its hindquarters and shift its weight backward in the transition, which temporarily achieves the self-carriage that the horse is not maintaining between transitions. The half-halt applied frequently — essentially creating mini-transitions within each gait — gradually develops the horse's ability to carry its own weight rather than depositing it in the rider's hands. Giving the rein momentarily — briefly releasing the contact to see whether the horse can maintain its balance and frame without the support of the rein — both tests and develops self-carriage: a horse that collapses when the rein is given is showing that it was dependent on the contact for support rather than genuinely through. The temptation to resist the leaning horse with stronger rein pressure is counterproductive because it gives the horse something to push against — a horse that leans against resistance tends to lean more. The correct response is to make the hands unavailable for leaning while developing through gymnastic work the hindquarter engagement and self-carriage that allows the horse to carry itself rather than relying on the rider's hands.