Why do horses eat dirt?

Geophagia, a disorder characterized by eating substances of little or no nutritional value, can be caused by a number of factors.


My horse constantly licks the ground at one spot in his paddock. As far as I can tell, the area is just the clay-like soil we have in this area. I’ve had people tell me he’s looking for some particular nutrient his diet is missing, but he’s on a well-regarded commercial feed and gets lots of grass in spring and summer and hay in winter. He also has a salt block. Other people have told me that it’s a stereotypy like cribbing, but he doesn’t seem stressed out to me and he doesn’t have any other bad habits. The dirt patch is in the middle of the field, so it would be hard to fence off. If I had to, I suppose I could get a giant boulder to put over it. Is that necessary?

Geophagia is a type of pica, a disorder characterized by eating substances of little or no nutritional value. (Getty Images)


I suspect your horse has . Forms of pica most often seen in horses include coprophagia (ingesting feces), lignophagia (chewing and eating wood) and geophagia (eating soil or dirt). Pica is a common problem in horses.

While the underlying cause of pica remains unknown, nutritional imbalances—particularly deficiencies in some minerals such as calcium, sodium, copper, iron or vitamins—are believed to contribute to the behavior. This is not always the case, however. Where there is no evidence of nutritional inadequacies, pica may be the result of curiosity or boredom.

Understanding geophagia

Geophagia, specifically, is a concern because excess soil consumption can cause irritation of the gastrointestinal tract. But any form of pica can cause gastrointestinal problems, including impaction colic, enteroliths, parasitic infestation or tissue damage from the ingestion of foreign objects.

The timing of geophagia may reflect a lack of certain nutrients in spring grass because anecdotal evidence suggests this behavior occurs primarily in horses returning to pasture after winter stabling. The nutrient content of forage can vary greatly with maturity of the grasses, fertilization, management and other environmental conditions. Therefore, even if a horse consumes an adequate volume of hay, he may not receive all the nutrients he needs. To determine the nutrient content in forage it is best to have it analyzed by a forage testing lab. Even a horse fed a well-regarded commercial feed may receive insufficient amounts of particular nutrients depending on his individual needs.

What you can do

I recommend you look at your horse’s diet and his environment and consult with your veterinarian. I would also advise that you check with an equine nutritionist to ensure that your horse  is getting the appropriate level of calories, proteins, vitamins and minerals according to his workload. If his diet  is well-balanced in terms of nutrients, and a veterinary exam rules out severe parasite infestation, then other factors such as boredom or loneliness might  be the trigger. In this case, allowing time for socialization with other  horses may help control or eliminate the behavior.

Gulsah Kaya Karasu, Dr.Vet.Med.
AGG Equine Nutrition Consulting
Van Hall Larenstein University of Applied Sciences, The Netherlands

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