Colic: Diet Can Reduce Enterolith Risk, Review Finds

If your horse is at risk for intestinal stones or enteroliths (a common cause of obstruction-induced colic in horses), consider replacing an alfalfa-based diet with grass hay, said Diana M. Hassel, DVM, PhD, of Colorado State University.

Hassel and colleagues evaluated two equine diets and water supplies to see their effect on minerals and the pH of the gut. The gastrointestinal tracts of horses with stones tend to be more alkaline and have higher mineral content. Half of the study horses had undergone surgery in the past to remove intestinal stones, and the other half had no history of stones.


An enterolith inside a horse's colon, which can cause colic
Enterolith after being removed form a horse's colon

An enterolith before and after surgical removal at Washington State University. This particular one weighed 3.6 kg and measured 20 cm around. The horse survived and recovered well.

"We found that horses fed alfalfa had a higher pH (more alkaline) in their gut than those fed grass hay," she said.

Another factor in stone formation appears to be stall confinement versus pasture turnout.

"Horses that are routinely turned out to pasture are at lower risk for enterolithiasis," she noted. "There is also a strong breed predilection for the Arabian and Morgan horse breeds, and a slight predilection in American Miniatures, but it can occur in any breed."

Intestinal stones are more prevalent in certain areas of the country, most notably Texas, Florida, and California. In California, intestinal stones represent up to 25% of the surgical colic caseload. But the overall prevalence of the condition seems to have decreased somewhat over the last two decades.

Because water contains minerals, it stands to reason that it could affect stone formation, however, Hassel did not see a difference when horses were given filtered vs. non-filtered water.

"We were not able to detect many changes within the colon in response to softened/filtered water in this study, but the role of phosphorus was not investigated, so the potential exists that water filtration may also impact enterolith formation," Hassel noted.

The study, "Influence of diet and water supply on mineral content and pH within the large intestine of horses with enterolithiasis," is scheduled to be published in the October 2009 issue of The Veterinary Journal. The abstract is available on PubMed.

About the Author

Marie Rosenthal, MS

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