What are your horse’s odds of developing colic or gastric ulcers? The answer may depend in large part on you. “Gut issues are always a threat to horses, but you can take steps to reduce the risk,” says Liara Gonzalez, DVM, PhD, DACVS, an assistant professor focusing on gastroenterology and equine surgery at North Carolina State University.

To protect your horse from GI threats, she advises, start by copying nature in what, when and how you feed him. In this article Dr. Gonzalez outlines six steps that will put you on the right path.

1. Feed Forage

You can meet most of your horse’s nutritional needs with high-fiber forage, like hay and grass. “Forage is the most natural food source for horses,” Dr. Gonzalez says, “and the act of chewing and eating forage stimulates the gut.”

After all, your horse is a grazing animal, built to roam around munching grass all day. His entire GI tract is designed to process small amounts of forage continuously. A steady flow of chewed forage soaks up digestive juices in the stomach and buffers acidity that could cause gastric ulcers. Farther along, in the cecum and hindgut, helpful microbes break down fibrous plant material and extract nutrients.

Steady forage intake helps keep the horse’s gut microbes in balance and his gut functioning as it should. When horses are stalled and fed intermittently, risks of colic and gastric ulcers begin to rise. Here’s what to do:

• Maintain pasture. Green pasture is a great source of nutrients for most horses. (For some, too much green grass increases the risk of laminitis, an inflammatory disease that weakens the bond between the hoof wall and the underlying bone. Hay is a better forage choice for them.)

• Feed hay free choice when good pasture isn’t available or appropriate. “Offer hay all the time,” Dr. Gonzalez says. This mimics the horse’s natural foraging habits and helps keep his GI tract running smoothly. Most horses easily consume 2 percent of their body weight in hay daily.

• Test forage quality. Hay should be pliable, sweet-smelling, and free of weeds, mold and dust—but those qualities don’t tell you much about its nutrient content, which can vary widely. “Your state Cooperative Extension Service or land-grant university can analyze hay or pasture grass and tell you what it provides nutritionally,” Dr. Gonzalez says. (If you buy hay by the bale, ask your suppliers if they test. Your Extension office may also have information on typical nutrients in hay grown in your region.)

• Tailor forage choices to your horse’s specific needs. For example, including some alfalfa in forage may help a horse who is prone to gastric ulcers. Research shows that alfalfa hay can lower stomach acidity for as long as five hours after feeding.

• “If your horse is overweight or tends that way, give him ‘chewing hay’ that’s less nutritionally dense but still good quality. He’ll have something to put in his stomach without taking in so many calories,” Dr. Gonzalez says. Slow-feeder hay nets and bags are another way to give horses constant access to hay without risking unhealthy weight gain.

“Overweight is as bad as underweight when it comes to health, so be aware of body condition and adjust your feeding program accordingly. Use a weight tape to monitor changes in weight,” Dr. Gonzalez suggests. A tape doesn’t give an accurate measure of actual weight, but it will let you see if the horse is gaining or losing. If you’re worried that he’ll be short on vitamins and minerals, give him a single vitamin-mineral supplement balanced to complement his hay.

When good hay isn’t available (or if your old horse has trouble chewing it), turn to substitutes. “Bagged, chopped hay is expensive but good,” Dr. Gonzalez says. “Hay cubes are also good, but be sure to soak them in water before feeding.” (Fed dry, the cubes may contribute to choke, in which a wad of feed blocks the esophagus.) Processed complete feeds that are designed to replace hay are another option. These feeds contain mixtures of grain and forage and generally have more calories per pound than hay.

2. Feed Concentrates Wisely 

“Show horses, and others with high-energy demands typically need more calories than hay alone provides,” Dr. Gonzalez says. Grains and processed concentrates are high in carbohydrates and provide lots of energy, but they carry risks. “Large amounts, especially large amounts of grain feeds high in sugars and starch, change gut pH and motility,” she explains. These changes increase the risk of intestinal gas and impaction. Excess carbohydrates are also linked to laminitis.

Follow best practices:

• Pick the right product. Many commercial feeds are formulated to complement different forages and to suit horses at different stages in life. For example, young horses need extra energy, protein and the right balance of minerals for growth; senior horses may develop digestive or metabolic problems that call for changes in diet. Feeds labeled “balanced” provide necessary vitamins and nutrients, so horses getting these feeds generally don’t need vitamin-mineral supplements.

• Feed the least amount necessary to meet your horse’s nutritional needs, based on his activity level and his age. Measure quantity by weight, not volume.

• Divide grain and processed concentrates high in sugar and starch into several small feedings a day, spaced at least five hours apart. One rule of thumb limits the amount at any single feeding to half a percent of the horse’s body weight, and the daily total to one-and-a-half percent.

• Feed fat for extra calories: Fats and oils are rich in calories and don’t carry the risks of colic and laminitis that starches and sugars do. Instead of feeding larger amounts of grain if your horse needs more energy, slip some vegetable oil or a commercial high-fat supplement into his feed.  

3. Feed Consistently 

Abrupt changes in your horse’s diet—a different concentrate, a new load of hay or sudden access to lush pasture—can trigger loose manure or even colic. Gas production often increases as the microbes in the horse’s gut adjust. To avoid problems:

• Make changes in the type or amount of your horse’s rations gradually. Mix new hay or feed with old, gradually increasing the proportion of new over five days or so. If you’re adding fats or oils, go even slower. Start with small amounts (like a quarter cup of oil divided among feedings) and make small increases every few days. If your horse isn’t used to pasture, start by letting him graze for a half hour or so and gradually increase the time.

• Choose a quality commercial feed—it’s likely to be more consistent in content than a mix from a local mill.

• Don’t rush exercise. “During exercise, blood leaves the intestines to provide oxygen where it’s needed most—heart, brain, large muscles,” Dr. Gonzalez says. “Allowing time after feeding before exercise is generally a good idea, but it can depend on what is fed and what the exercise consists of.”

4. Make Sure He Drinks

“Horses should always have access to water,” Dr. Gonzalez says. Dehydration is a major health risk and can lead to impaction colic, not to mention kidney damage and other severe outcomes. To ensure that your horse drinks his fill:

• Provide fresh, clean water at all times. Dump, scrub and refill water buckets daily and top them off through the day. Keep outdoor water troughs filled and clean them at least every couple of weeks. If you use automatic waterers, clean them regularly and check often to be sure they’re working properly.

• Keep tabs on water consumption. An idle 1,100-pound horse typically drinks 6 to 10 gallons of water a day, but factors like heat and exercise levels can increase that amount by 50 percent or more. Diet is a factor, too—pastured horses get moisture from green grass and may drink less than stalled horses.

• Let him drink after exercise. Old beliefs notwithstanding, there’s no evidence that it’s harmful. And if the horse has lost fluid through sweat, he needs to replace it ASAP.

• Let him drink on the road. “On long trips, stop and offer water every couple of hours,” Dr. Gonzalez advises. “Some horses refuse unfamiliar water, so take portable water containers from home.” At shows, offer water at least every hour—don’t wait until your classes are done and you’re back at the trailer.

• Keep him drinking in winter. Many horses seem to prefer room-temperature water—neither warm nor very cold—and may drink less when their water is frigid. Add a little warm water to buckets during cold spells and use heaters in outdoor troughs.

There are more ways to encourage water consumption at times when your horse may not drink enough: Soak hay to sneak some extra moisture into his diet. Provide salt to stimulate thirst, in a salt block or added to his concentrate before going on the road.

“You can disguise the taste of unfamiliar water by adding apple-flavor electrolytes or by adding a bit of sweet feed to his water, but be sure to provide a bucket of plain water alongside,” Dr. Gonzalez says. “Experiment at home with these solutions—don’t wait until you go to see what he will accept.”

5. Turn Him Out

Stabled horses colic more often than horses who spend most of their time outside, research shows. They’re more likely to develop gastric ulcers, too. Moving around at liberty mimics the horse’s natural lifestyle and stimulates gut activity. “My horses are not stalled, which is ideal but not possible for everyone. People have to work with what they have,” Dr. Gonzalez says. Here’s what to do:

• Give your horse as much time out as possible. When turnout is limited, light exercise can also help keep his digestive system in good working order.

• Turn him out with a compatible buddy (or buddies) if you can. Horses are herd animals, and lack of contact with others can be stressful for them.

• Patrol paddocks and pastures for poisonous plants and debris your horse could accidentally ingest. Check for signs of chewing on fences or other objects. Some horses develop enteroliths, rocklike objects that form when mineral layers build up around a foreign object that ends up in the gut. These stones can grow large enough to block the intestine.

• If the soil is sandy, consider supplementing your horse’s diet with psyllium (see “Digestive Supplements” on page 98). Sand ingested as the horse grazes can build up in the intestines, leading to colic. If he’s turned out in a sand paddock, put his hay in a feeding rack or a hay net, with a stall mat underneath to catch whatever falls to the ground.

6. Follow Best Practices

Good stable management provides more ways to ensure gut health:

• Block parasites. Intestinal parasites, including tapeworms and small strongyles, are linked to problems ranging from diarrhea to impaction colic. Work with your veterinarian to set up a deworming program that makes sense for your horse, with annual or biannual fecal egg counts that check effectiveness. “We’ve moved away from treating all horses on the same schedule because we don’t want parasites developing resistance to the deworming medications,” something that has already started to happen, Dr. Gonzalez says.

• Call the dentist. If your horse can’t chew his feed properly, he’s at greater risk for impaction and choke. Moreover, poorly-chewed food may not be fully digested, so he misses out nutritionally. “Every horse should have an annual or biannual dental exam,” Dr. Gonzalez says. “Teeth may not need floating but should be checked at least once a year as a preventive, especially as the horse ages and his teeth show more wear.”

• Use meds as directed. Antimicrobial drugs can kill beneficial gut bacteria along with microbes that cause disease. Nonsteroidal anti-inflammatory drugs such as phenylbutazone and flunixin meglumine (Banamine) reduce inflammation, but long-term use of NSAIDs has been linked to colic, ulcers and inflammation in the hindgut. These drugs are invaluable, but they should be used only when prescribed by the veterinarian.

• Be watchful. Know your horse’s normal behavior patterns and watch him closely to spot subtle changes that may signal the start of GI trouble. You can’t always prevent these problems, but prompt treatment can be the key to a happy outcome.  

Digestive Supplements

Search online and you’ll find dozens of different digestive supplements for horses. There are products with probiotics (live bacteria and yeasts thought to aid digestion), prebiotics (enzymes and yeast extracts to nourish those microbes), amino acids such as glutamine and threonine, antacids such as bicarbonate, psyllium (to help lubricate the colon and move material through) and more.

Speak with your veterinarian if you think a supplement might help your horse and do research before you buy, says Dr. Liara Gonzalez, DVM, PhD, DACVS. “Ask: Where is the data? Some companies have paid researchers to conduct tests to support their claims. That doesn’t mean the results are not valuable but find out what kind of testing was done and if the results were published.” Studies can be published in peer-reviewed scientific publications.

Quality is another issue. Products from established makers are generally more likely to be consistent from batch to batch, but there’s little oversight of supplements. For the same reason, Dr. Gonzalez cautions against using compounded versions in place of FDA-approved gastric-ulcer medications (GastroGard and the preventive UlcerGard are FDA-approved).

How will you know if the supplement you choose helps your horse? “First decide what benefit you’re looking for and what will be your metric of success,” Dr. Gonzalez says. “Then change one thing and see.” Knowing what you want from the supplement and how you will measure improvement will help make your assessment less subjective. 

This article was originally published in the Winter 2019 issue.