When horses pace back and forth near a fence it is usually a sign of anxiety. If you have a horse that is walking back and forth restlessly in one area, possibly wearing a track in the dirt or grass, this could be a sign that your horse is nervous, worried, or anxious for something to happen. Other signs include flaring nostrils, or calling (neighing loudly) into the distance. This is a problem that should be addressed. Horses that are nervous or anxious not only have trouble focusing and behaving when being ridden, but will commonly make themselves sick. At best, a horse that paces will burn calories, lose weight, and wear their hooves painfully short, at worst a worried horse can make themselves colic -- a very serious, frequently fatal, horse sickness.
If your horse is exhibiting this behavior of walking or pacing back and forth by a fence or gate, you should try to determine why your horse may be nervous or anxious. Is your horse alone, or was it recently separated from a pasture companions? This behavior is frequently seen in horses who are lonely. Horses are herd animals that were designed to be to live in groups, not alone. Horses are type of animal that crave companionship both emotionally and for safety. For example, when horses are in a group setting they will never all sleep at the same time. They rely on each other, one horse will stay away while the others doze and they will take turns through the night. If a horse has no other horses to be pastured with, they may exhibit pacing or other signs of anxiety from being alone.
If you keep your horse alone without another horse and experience your horse pacing back and forth by the fence persistently, your only solution may be to acquire another horse, adopt a small pony, or board a horse for a friend. Using, this will stop a solitary horse from pacing near the fence.