Horses typically chew on the wood parts of barns, fences, etc. for 3 reasons. The first reason is that often there is too much time left in the day between meals so that serious boredom occurs. As a result, wood chewing is simply something to do to pass the time. The second reason is that something in the horse’s environment is a source of frustration. So wood chewing, in that instance becomes a displacement behavior in the face of the frustration. The third reason, which is rare when horses are fed a balanced diet, is that something is missing in their diet, so the horse is using the wood to potentially fill a nutritional hole. This problem is known as pica.
There are several problems with wood chewing. First, the splinters produced can damage the horse’s mouth, throat, and stomach. Second, a large amount of consumed wood can potentially cause colic. Third, it can easily compromise a secure barn or fence.
If you suspect your horse has pica, then a veterinary exam and possible bloodwork can aid in finding what nutritional supplements might be needed. If your horse has access to a turnout area then regular turnout will help both boredom and frustration, especially if the turnout contains safe food to eat ( grass or fresh hay ) or distractions ( other horses nearby to interact with ). If regular turnout is not an option or is not adequately addressing the chewing problem then consider other ways of occupying the horses time. Increasing the horses exercise level/frequency is a consideration. Increasing the frequency of feeding from two to three or four times daily will occupy more of the horse’s time. A slow feeder will force the horse to take longer to eat so that feeding times are longer and use up a larger portion of the day. Applying a chemical deterrent or covering the wood with metal is also an option. Address sources of frustration that the horse may be subjected to, surrounding animals which the horse does not like or a noise or persistent stimulus which the horse does not like are examples.
Working to reduce wood chewing will both benefit your horse’s health as well as their environments appearance and integrity.