Possible Reasons Why Horses Eat Dirt

Q. My horses eat dirt, even with mineral and salt blocks available to them. I also give them vitamins and digestive enzymes. Why do they do this?

Susan Horner, Fulton, Mo.

A. Your question is a common one! There are several theories about why horses eat dirt (a behavior known as “geophagia”), including nutritional imbalances and boredom.

Consuming a little dirt or sand usually goes without incident, but ingestion of large amounts can lead to serious digestive problems in horses. If you notice a change in stool consistency (i.e., diarrhea) or signs of colic, you should contact your veterinarian immediately.

Studies of the effectiveness of feeding psyllium to help rid the digestive tract of excess sand or dirt have reported mixed results. It certainly won’t hurt, but it might or might not help. A 2001 study in Australia evaluated 13 sites where horses were eating dirt, and it was found that the soil samples contained elevated levels of iron and copper compared to controls. The study results suggested these elements might trigger dirt eating, but more research is needed to be certain.

You made no mention of the type or amount of forage available to your horses. If you feed good quality hay and/or if adequate pasture is available, dirt eating may be a simple case of boredom. Work with your veterinarian to ensure your horses are healthy and do not have a high parasite load. Also, if you are unsure if your horses’ diets are completely balanced, I encourage you contact an equine nutritionist to help you complete a full evaluation of the rations.

About the Author

Nettie Liburt, MS, PhD, PAS

Nettie Liburt, MS, PhD, PAS, is an equine nutritionist based on Long Island, New York. She is a graduate of Rutgers University, where she studied equine exercise physiology and nutrition. Liburt is a member of the Equine Science Society and is currently senior equine nutrition manager for Mars Horsecare US/Buckeye Nutrition.

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