How do you fix a horse that bucks when asked to lope or canter?

A horse that bucks specifically at the lope or canter departure is telling you something specific about that transition, and Clinton Anderson's diagnostic approach targets the cause before the correction. The most common cause in Anderson's experience is that the horse is cold-backed or tight in the back at the point when the lope is asked. The canter departure requires the horse's back to round and its hindquarters to come under, and a horse with a tight, sore, or cold back may express objection to this demand specifically at the departure. Anderson checks saddle fit, back soreness, and whether the behavior is worse at the beginning of the ride and diminishes with warm-up — which would confirm a cold-back component. A second cause is that the horse has learned that bucking at the canter departure is effective — it either gets the rider off or gets the canter request removed. This learned behavior requires a different approach than a pain-based buck. Anderson's correction for the learned buck is to stay on, use the one-rein pull-to-the-side correction to stop the buck, then immediately ask for the lope again. Stopping the ask when the horse bucks teaches the horse that bucking removes the ask. Asking again immediately after the buck teaches the horse that bucking does not change what is being requested. For horses that have been bucking at the lope departure for years, Anderson may return to groundwork before the correction under saddle — specifically working on lope departures on the lunge line until the horse is taking clean, easy departures on the ground before the under-saddle departure is addressed again. A horse that bucks at the lope departure on the lunge line has a physical or fundamental training issue; a horse that lopes easily on the lunge but bucks under the rider has a rider-specific or weight-specific issue that needs different diagnosis.