In nature, the horse is a gregarious, roaming animal that grazes constantly. In captivity, the horse is frequently confined, alone, and without anything to chew. When you consider the changes in habits that we ask of the horse, it is amazing that he adapts at all. When pushed too far he will find ways to satisfy his physical and psychological needs and, like humans, what is too far varies widely from individual to individual. With repetition, these adaptations to an abnormal environment can become ingrained behavior that are impossible to eradicate.
A Biochemical Addiction
All of the common stable vices stem from poor adaption to captive management. They are mostly psychological adaptations that help calm the horse. Some of these vices even have established biochemical pathways and are analogous to drug addiction: the behavior causes the release of chemicals in the brain that relax the horse. With this is mind two points jump out:
Cribbing or Windsucking
The horse grabs onto a fixed object with his teeth, arches his neck and grunts. The behavior is usually brought on by boredom or frustration. It is said that horses can also learn this behavior watching other horses do it. Ample time on pasture and hay when stabled will go a long way to prevent this behavior from developing.
If started very early in the behavior, a cribbing strap may prevent the behavior from becoming fixed. Cribbing straps are effective for most confirmed cribbers but must be put on tightly. Cribbing straps vary in design and harshness. Use the mildest strap you can get by with. To prevent sores from developing, buy several cribbing strap covers and keep a clean cover on the strap by changing it every few days. A relatively new version marketed under the name "Miracle Collar", has proven to be very effective and most horses seem to be able to wear this collar without developing sores.
There is a surgery available that is fairly effective when done early. The modified Forssell's surgical procedure may provide the best results with a 60% success rate in one large study. Surgical treatments include bilateral buccostomy (creating bilateral buccal fistulae to prevent development of an oral vacuum), neurectomy of the ventral branch of the spinal accessory nerve (to prevent motor activity of the sternomandibularis muscle), Forssell's procedure (resection of a segment of the omohyoideus, sternothyroideus and sternomandibularis muscles), and the modified Forssell's procedure (transection of a large segment of the ventral branch of the spinal accessory nerve, and transverse and oblique sectioning of the cranial, middle and caudal aspects of the omohyoideus and sternohyoideus muscles).
This is a common behavior in horses that frequently does not have a nutritional basis but a psychological one. Check the horses diet to be sure it is balanced and adequate in amount. Provide a salt block if one is not available and be sure the horse has free access to hay or grass. Cover all the board surfaces with carboleum or angle iron. Trees can be wrapped with chain link fence to prevent debarking.
Pawing and weaving
Horses that weave, paw or walk the stall should be stalled as little as possible. The same management advice provided for cribbing and chewing is applicable here. Providing more exercise may decrease this behavior.