Q&A: A Gnawing Problem

Whether diet or boredom is to blame, gnawing on wood is an undesirable behavior. Here's how to identify the source of gnawing and break the habit.

QTwo fillies on my farm have started chewing the wood fence boards. The 19-month-old started first, and the 9-month-old followed soon after. They are the only horses on our farm, but they live within 10 feet of the three to five horses at our neighbor’s farm. They are rarely in stalls and have access to grazing 24-7. In addition, when the grass went dormant last winter, they got hay in the morning and again in the evening. They are turned out in paddocks that range from one and a half to two acres, so they have plenty of room to run. My husband and I groom them every day and walk them on leads at least once a day.

I’ve read that many horses chew wood due to boredom or lack of some nutrient. Both are also fed a concentrate twice a day at a ration that should meet their nutritional needs. We have two cats on our property that like to climb on the fences, so I’m hesitant to add electrical wire. Can you offer other suggestions to discourage or eliminate this bad habit?

A brown horse chewing on a weood fence
Many horses chew wood if their diet is lacking in fiber.

A: This is a problem for many horse owners. In wood chewing, horses actually gnaw on and ingest wood from their fence rails and other sources, in contrast to cribbing or wind sucking, when a horse grasps a surface with his teeth and sucks in air. As you mention, the two main causes of wood chewing are boredom or lack of something in the diet.

First, rule out a dietary deficiency. Horses will typically crave what is missing in their diet. Many horses chew on wood if their diet is lacking fiber. Lush pasture, for example, contains large amounts of soluble carbohydrates but may not offer enough fiber (nonsoluble carbohydrates) to meet a horse’s daily needs. If that’s the case, he will go somewhere else to find it—such as fences or tree trunks. Horses who are fed hay usually won’t have this problem, unless they are not getting enough.

So first, make sure that your young and still-growing horses are getting free-choice hay. Start by feeding enough so that the fillies are leaving a small amount after every meal, then decrease that amount slightly to reduce waste. Horses typically need 1.5 to 2 percent of their body weight in forage, so for example if your fillies weigh about 800 pounds, they need about 12 to 16 pounds of hay each. A grain ration formulated for young, growing horses will balance out their ration with all of the extra protein, vitamins and other minerals they need.

Now let’s look at boredom. Your fillies are fed twice a day, so they may have periods when they have eaten all of their hay and grain and are looking for something to do. Young horses will naturally chew on things when they’re bored, and they often start with trees, fences, feeders, toys or each other. If your schedule allows, try adding a third meal of hay into the feeding regimen. For example, feed the evening meal in the late afternoon, then add a serving at bedtime. Place the hay well away from the areas of the fence where they’ve been chewing. Keeping the horses’ mouths occupied longer with the hay might reduce the amount of time spent chewing. Also, consider purchasing some toys that are meant to be chewed on. These might deter the wood chewing by providing a novel playtime activity instead. 

If none of these strategies work, you can try a few mechanical deterrents. I hate suggesting this for young horses, but since electric wire is not an option for you, as a last resort you could try a grazing muzzle. Look for one that would allow the horses to eat and drink normally but would prevent them from getting the fence rails in their mouths. You might also try coating the wood with one of those products that are supposed to taste unpleasant to horses.

A more expensive option, but one that would last longer, would be to cover your fences with a “diamond mesh” or other horse-friendly wire that would extend from the ground to over the top rail by about two inches. This will protect all the fence boards and not be such a shocking experience for any feline friends!

Carey Williams, PhD
Equine Extension Specialist
Rutgers, the State University of New Jersey
New Brunswick, New Jersey

This article first appeared in EQUUS issue #439.




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