Q: What are the main factors that increase the risk for colic? How should I manage my horse to decrease these risks?
Kate Berkovich
Fairfax, Virginia

A: This is an excellent question. As a veterinarian I am glad to hear you are interested in learning about ways to decrease the risk of colic in your horse. Though one could write a book on all the factors that might predispose a horse to colic, I will focus on the factors you can manage daily.

To begin, it is important to understand that horses evolved as grazers and roamed throughout the day in search of scrub and grasses to consume. Feral horses will spend at least 60 percent of their day eating or searching for food. Their diets consist primarily of grasses, some green and lush, some fibrous and stemmy. Interestingly, horses that are managed like wild horses (turnout and pasture or frequent feedings of hay meals) tend to have less colic. One of the simplest things you can do is to try to manage your horse as he would be in the wild. Access to fiber (i.e. hay) frequently throughout the day will decrease the risk of some types of colic with the added benefit of giving him something to keep him busy and avoid boredom.

Providing fresh, clean water is also very important in preventing colic. It is important to remember that horses that are heavily exercised will sweat and lose both water and electrolytes. Horses’ water intake may be inadequate when they are overtired or experience sudden changes in environmental temperatures. During cold winter months, it may be helpful to provide some warm water daily as research has shown horses will drink better if the water is warm. Electrolyte water can be useful to replenish electrolytes in athletic horses in strenuous training, however, you should always provide access to fresh water in addition to any electrolyte or flavored water. A 1,000-pound horse should drink a minimum of five gallons of water a day. Monitoring your horse’s water intake is a good way to recognize a potential problem before it becomes severe, as many horses that are developing an impaction will have a drop in water intake.

In addition to monitoring water intake, you can learn a lot about a horse’s gastrointestinal health by simply monitoring his manure production. Both quantity and consistency are important as manure may become dry and mucus covered when a horse is developing an impaction. Horses on a primarily hay diet will pass 12 to 24 piles of manure on an average day.

While some horses require grain to maintain their weight, high-grain diets have been shown to be associated with an increased incidence of colic. Because grain has a poor buffering capacity, horses have an increased risk of gastric (stomach) ulcers when fed high-grain diets, particularly if they are fed grain without hay (which has a better buffering effect in the stomach). If you must feed grain, it is best to feed small meals (two to three pounds at each feeding) and feed it after some hay has been ingested. Grain should be primarily digested in the small intestine. If it reaches the cecum before it is completely digested, it will be fermented by bacteria in the cecum, causing gas and colic pain. Small meals of grain will ensure that the grain is well digested before it reaches the cecum.

We now know that many performance horses develop gastric ulcers—often without clinical symptoms. There are many predisposing factors for gastric ulcers. Stress—including sudden management changes, travel, strenuous exercise and sudden changes in feeding schedules—increases the risk of ulcers. If your horse exhibits signs of gastriculcer disease (mild to moderate recurrent colic pain particularly after feeding grain), contact your veterinarian to discuss diagnosis and treatment options. Currently, there are many unproven methods of treating gastric ulcers. Discussing the types of treatment with your veterinarian will help ensure that you are treating your horse effectively and appropriately.

An additional management practice that can lead to colic is feeding horses on the ground. Horses fed on the ground can ingest sand or dirt. If you live in a region with sandy soil, the sand can accumulate in the gastrointestinal tract and cause irritation or impaction. Clinical signs of sand accumulation include recurrent colic, occasional diarrhea, or if an impaction develops, severe colic. Prohibiting the ingestion of sand is the number-one way to protect against this type of colic. This means feeding your horse on a rubber mat or from a feeder to prevent him from eating off of the ground. If your pasture is very short, your horse may also eat sand while trying to get the last bit of grass of the ground, ripping the roots and sand up with the blades. While feeding psyllium products may aid in preventing sand colic, it is not 100 percent effective. It is clear that the best way to prevent sand colic is to prevent ingestion of sand from the start.

Parasite infestations can also result in colic, weight loss and diarrhea in both young horses and adults. Resistance to anthelmintics (dewormers) is becoming an increasing problem in the world. Consequently, we can no longer assume that regular deworming means “parasite free.” It is important to run fecal exam both before and sometimes after deworming to determine if your parasite-prevention program is effective and whether or not you have resistance problems in your herd. Your veterinarian can consult with you to assess your parasite-prevention program and determine the best plan of action. Certain parasites, including tape worms, cannot be detected on fecal exams. It is important to deworm for these parasites atleast once a year after a killing frost as tapeworm infestations can result in worm impactions and colic.

Finally, dental problems, especially in the older horse, can result in poor mastication of feed and subsequent impaction of fibrous material. Horses’ teeth will continue to erupt throughout the majority of their lives. As they grow, the teeth are continually worn down by the horse grinding fibrous feed material. Aged horses’ teeth will eventually stop erupting as they reach the end of the root. At this point, horses will continue to wear down their teeth until there is little to no grinding surface left. Consequently, older horses may no longer be able to chew hay effectively and may require a change to a pelleted complete feed to prevent impactions from improperly masticated feeds. Routine dental exams by your veterinarian to ensure adequate dental function is another important management tool to prevent colic due to fibrous feed impactions.

While there is no magic potion or management tool to completely prevent colic, remember that if you feed your horse as he would normally eat in the wild, avoid sudden changes in diet, exercise and management practices, and institute a good preventive health program, you can significantly decrease the risk of colic in your equine partner.

Elizabeth Carr, DVM, PhD, Dip. ACVIM and ACVECC, is an associate professor in the department of large animal clinical sciences, College of Veterinary Medicine, Michigan State University. Her research includes equine sarcoids and respiratory viruses. She rides two Trakehner geldings at Second Level.