A refusal is a term used in horse riding, when the horse does not jump a fence to which he was presented. This includes any stop in forward motion. A run-out is when the horse quickly slides past or "ducks out" of a fence instead of jumping it, without stopping forward motion.
Refusals also have the potential to unseat the rider, which may result in rider injury, such as that of Christopher Reeve. Refusals also present as the possibility that the horse crashes into the obstacle. In extreme cases, however, it may be best for a horse to refuse rather than jump a fence which he can not clear, as he might land on the fence, fall on landing, or flip over.
In any case, especially if the horse has begun to refuse frequently when before he was quite willing, a veterinary exam should be performed to rule out pain.
When pain is ruled out as a factor, the rider should first look at himself, and evaluate whether his riding is causing the refusals. Rider error is a very common cause for refusals, poor riding may place the horse in a position so that he physically would find it extremely difficult to clear the obstacle (such as too far or too close to the jump). Additionally, riders who do not release over the fence, preventing the horse from stretching down, will hit the horse in the mouth with the bit, and cause pain. If this happens frequently, the horse will associate the pain with the jumping effort itself, and may begin to refuse. The rider must remember that it is his job to get the horse correctly to the fence, with adequate speed and impulsion, and his job to stay out of his way while the horse takes the jump. Horses that have begun to refuse due to rider error may need to go back to more basic work, regaining their confidence, before attempting to jump courses or larger fences again.
If the horse is refusing out of pure disobedience, more drastic measures must be taken. Most riders prefer to hit the horse once or twice with a crop, behind their leg, to tell the horse that the refusal was unacceptable. This is especially favored if the horse is refusing out of habit. Horses that refuse due to fear are usually given more leniency, especially if they are green or young, with the rider working to build up the animal's confidence. Horses that are refusing because they are "sour" are best dealt with by giving them a long break from jumping. In this case, it is often best to give the horse time off, so that they happily begin to jump again. The horse is likely to try much harder for his rider if he likes what he is doing.
Lastly, the horse may be physically unable to jump a fence of a certain size or height, even with the best riding. In this case, there is nothing the rider can do, and the horse should be given a job to which he is more suited, rather than trying to push him past his limitations. Pushing a horse, even those with the best natures, may result in physically damaging the animal or causing him to hate being worked.