7 Tips for keeping your horse's digestive system healthy

Some simple management measures can help reduce your horse’s risk of colic, ulcers and other tummy trouble.

1. Maximize pasture turnout.

Overall, the key to keeping a horse’s digestive system functioning well is to mimic nature as closely as possible. Horses with access to ample pasture will spend as much as 18 hours a day grazing, and that’s exactly what their digestive tracts are designed for—a near continuous supply of chewed grass.

Of course, that’s not always possible. Some horses have issues, such as a susceptibility to laminitis, that require their access to pasture be limited. And some easy keepers simply get too fat if allowed to graze around the clock. But even those who must have their grass intake limited— with a muzzle, perhaps—will still benefit from the exercise and socialization they gain from being at liberty in their pastures.

2. Feed good-quality hay.

Forage is the foundation of a healthy equine diet. If your horse’s teeth are in good shape but he seems to waste large quantities of hay, take a closer look at your bales. Coarse, stemmy hay is difficult to chew and digest. Nutritious hay will generally be greenish in color and smell fresh and slightly sweet.

3. Don’t let your horse’s stomach empty out.

Gastric ulcers are common in horses, in part because of the modern practice of offering feed in one or two large meals per day, which leaves his stomach empty most of the time.

The horse’s GI tract is designed for continuous grazing, so his stomach is always producing acid. Feeding hay free-choice allows a continuous intake and keeps the horse’s stomach full longer. So, too, can dividing his hay ration into smaller portions that are fed throughout the day. The main buffer for acid in the stomach is saliva. A horse produces about twice as much saliva daily when eating hay or grass than when eating grain.

4. Go easy on the grain.

Some horses— growing youngsters, broodmares, elderly pensioners, hard-working athletes, for example— require more calories and nutrition than forage alone can provide. For centuries, the solution had been to give horses grains and, more recently, other nutrient-dense feeds.

However, grains can be high in sugars and starches, which when consumed in too high a quantity at once can cause colic or laminitis. This makes sense when you consider how a horse’s digestive tract functions: In order to utilize a fibrous food like grass, herbivores must ferment the chewed matter to extract the nutrients. Most herbivores are ruminants—animals such as cows, sheep, goats, deer and camels have multiple stomachs, one of which serves as a large fermentation area. Horses have a relatively small, single stomach (holding two to five gallons, compared to a cow’s, which holds 15 to 30), followed by the small intestine; then the horse has a large

cecum and hindgut, which is where his fermentation occurs. “The horse’s digestive tract is designed to get food down to the hindgut as swiftly as possible,” says Anthony Blikslager, DVM, PhD, of North Carolina State University.

“If you feed a lot of grain/sweet feed, the horse will not be able to absorb all the sugar from it before it gets to the cecum and colon,” says Blikslager. “The hindgut is designed to digest grass, and if all of a sudden it gets sugar, this has an adverse impact on the microbial population. It changes the pH and type of bacteria. The bacteria that can digest sugar quickly multiply and form a lot of gas in the process.”

5. Replace some carbohydrates in your horse’s diet with alternative caloric sources.

Vegetable oils are commonly used to help keep weight on older horses as well as add energy to the rations of high-performance horses. Corn oil is a popular choice because it’s inexpensive and horses generally find it palatable, but flax, canola and other products are also acceptable.

Oil is readily absorbed and doesn’t contain starch or sugar, so it’s a safer way to increase calories in a ration than grain. Adding oil to the diet can also reduce the risk of ulcers by slowing the rate at which the stomach empties, which keeps more material in the stomach longer and in turn helps keep the acid levels under control. As a bonus, oil will give your horse’s coat a healthy sheen.

Another option for safely adding calories to your horse’s diet is to switch to one of the newer high-fat feeds. Many of these products incorporate beet pulp or soybean hulls, which provide fiber as well as energy. “A highfiber commercial feed is usually better than straight grain or sweet feed,” says Blikslager. These feeds contain less starch and sugar and are digested more like roughage than grains, and so they reduce the risk of serious gas colics and laminitis.

6. Keep your horse from ingesting too much sand.

In general, it’s best to feed hay off the ground. When a horse lowers his head to eat, gravity helps drain fluids containing dust and particles out of his nose and sinuses. However, if you have sandy soil, a horse who eats off bare ground may ingest enough of the particles to form “dams” that block the

“The horse’s digestive tract is designed to get food down to the hindgut as swiftly as possible,” says Anthony Blikslager, DVM, PhD, of North Carolina State University.

Made from the ground seeds of the Plantago plant, psyllium is a proven laxative. When ingested it swells and forms a gel-like substance that helps push sand through the horse’s intestine.

intestine, a condition called sand colic.

If sand is an issue for your horse, place your hay in a feeder or hay net, or feed off a stall mat on the ground. Commercial feeders are available, but a number of “found” items, such as a leaky but structurally sound water trough, will also serve the purpose.

You may also want to add psyllium to your horse’s diet as a precaution. A proven laxative, psyllium is made from the ground seeds of Plantago plants; when ingested, it swells and forms a gel-like substance that helps push sand through the intestine.

7. Protect your horse’s gut flora.

A horse needs a healthy, wellbalanced population of microbes in his gut to help him digest food and absorb nutrients. Some of these microorganisms are essential for creating necessary nutrients as well. Many factors in a horse’s life—including the stresses of transport and competition or the administration of antibiotics—can disrupt this microbial population. If the good flora levels drop too low, the horse may develop chronic diarrhea, he may lose weight or just generally fail to thrive, or he may become susceptible to various types of colic.

To help a horse replenish and maintain healthy populations of gut flora, a number of supplements are available that contain probiotics, live microorganisms to “reseed” the gut. Many also contain prebiotics, nutrients which feed the beneficial bacteria. Some prebiotics also contain nondigestible sugars that bind with pathogens and carry them out of the gut with manure.

“I feel it’s beneficial to have a small amount of these important microbes added to the diet on a daily basis,” says Amy Gill, PhD, an equine nutritionist with a practice in Lexington, Kentucky. “The life cycles of these microbes are short. It’s better to have them available in each feeding, as opposed to waiting until something bad happens and then trying to fix it.” Direct-fed microbials (DFM) are available in some commercial feeds as well as supplements.

As always, consult with your veterinarian or an equine nutritionist before making any changes in your horse’s diet, especially if you are trying to address a specific issue. With guidance, you may well find several ways to safeguard your horse’s digestive health. Adapted from “10 Ways to Optimize Your Horse’s Digestive Health,” (EQUUS 388)