SmartPak Store Hosts Discussion on Gastrointestinal Disease

Horse owners gathered Jan. 9 at the SmartPak Retail Store in Natick, Mass., to hear a presentation on equine colic by Lydia Gray, DVM, MA, medical director/staff veterinarian for SmartPak.

Gray provided a summary of a lecture from the 2007 American Association of Equine Practitioners Annual Convention covered gastrointestinal disturbances. The AAEP lecture was titled "How to minimize gastrointestinal disease associated with carbohydrate nutrition in horses," and was presented by Ray Geor, BVSc, MVSc, PhD, Dipl ACVIM, and Pat Harris, MA, PhD, VetMB, Dipl ECVCN.

The good news is that horses have evolved a highly efficient mechanism to obtain energy and other nutrients from forage: the fermentation vat known as the cecum. The bad news is that even highly digestible forage cannot meet the needs of horses in heavy work, and we must feed them more dense sources of energy like grain. Many studies have shown large amounts of grain to be a risk factor for gastrointestinal (GI) disturbances such as colic, and also gastric ulcers. However, there are other reasons for gastrointestinal disease such as abrupt changes in diet (either hay or grain), feeding practices (e.g. few large meals per day instead of constant grazing), exercise patterns and housing, and inappropriate parasite control programs.

Much of the blame for GI disturbances can be placed on sugars and starches (non-structural carbohydrates or NSC). First, the small intestine (the primary area where NSC is digested and absorbed) has a limited capacity for handling sugars and starches. Second, when the small intestine becomes overwhelmed with these substrates, they end up in the horse's hindgut, specifically the cecum, where bacteria rapidly ferment them. This fermentation can cause an increase in lactic acid and gas.

The presenter made several recommendations for minimizing digestive disturbances due to high levels of sugars and starches:

1)Feed horses more frequently and try to extend the feeding time.

2) Feed at least one pound of long-stem forage per 100 pounds body weight (for an 1,100 pound horse, this would be 11 pounds).

3) Limit the sugars and starches to the hindgut:

  • Feed no more than about 4 ½ lbs of grain per meal to an 1100lb horse;
  • Feed sugar/starch that is more readily digested in the small intestine (oats is preferred over corn and barley);
  • Use other sources of energy such as fat, beet pulp, and soy hulls;
  • Restrict access to pasture and feed low NSC-forage.

4) Make diet changes involving hay and grain gradually.

5) Consider using active live yeast to stabilize the hindgut.

The next GetSmart lecture "How to Keep Weight on Your Horse: Managing the Hard Keeper" will be held at the SmartPak Retail Store in Natick, Mass., Feb. 20, 2008. For more information and a complete presentation schedule visit  

About the Author

Lydia Gray, DVM, MA

Lydia Gray, DVM, is Medical Director and Staff Veterinarian for SmartPak Equine. She was previously the executive director of the Hooved Animal Humane Society in Woodstock, IL, and an Owner Education Director for the American Association of Equine Practitioners.

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