Turnout, diet, and water consumption are critical considerations when avoiding colic. In this guest blog originally featured on The Horse, equine health expert Anthony Blikslager, DVM, PhD, Dipl. ACVS, discusses ways to avoid colic through effective management. 

The age-old disease of colic can best by managed be returning the horse–as much as possible–to its natural environment. This means horses should be turned out as often as their schedules and environments allow, and they should be fed rations composed predominantly of forage (grass or hay). There are limitations to this approach in areas where horses are housed in intensive farms, and dietary limitations apply to some breeds such as the Thoroughbred, a breed that often requires more concentrate feed to meet energy requirements. Finally, horses should be provided with a clean and readily available water source so they remain well-hydrated.

Alternative methods of avoiding colic, such as probiotics, have insufficient scientific evidence of efficacy, so we will limit our discussions to the three big management keys to preventing colic–turnout, diet, and water. Then we’ll look at some instances when colic might occur more frequently, so you can be prepared.

Turnout

Horses evolved to graze approximately 18 hours a day. There is something about moving and grazing all day that likely reduces colic, although this has not been proven. There are a number of factors that make it difficult to manage them optimally, such as boarding conditions, show schedules, and convenience for riding. However, turnout on sufficient acreage should be as close to the minimum 18 hours as possible. A good guideline is five acres per horse, but less can be satisfactory, presuming there is adequate grass available on the farm. Horses can be managed in dry-lot conditions if the feeding program, routine care, and exercise are consistent with appropriate husbandry guidelines.

Owners should carefully plan how many horses they can accommodate on a farm before acquiring too many horses. Well-managed farms still can have a lot of horses in a relatively small space, but it is worthwhile recognizing that this is a factor that will predispose horses to colic.

Other factors that can limit turnout include owners’ impressions of how horses should be managed. For example, there is the concern that when the weather is cold, horses should be kept inside. The solution to this is to blanket horses–they can and should be turned out unless the weather is particularly harsh. You can provide shelter from sun, wind, rain, or snow by putting run-in sheds in each of the pastures. Horses often will choose to be outside even in inclement weather.

Another factor is convenience. Many owners work all day, and they like horses to be readily available when they get to the farm. This again reduces turnout and increases the likelihood of colic.

Diet

Horses are hindgut fermenters; they have adapted to digesting forage using a symbiotic relationship with microorganisms in the cecum and colon. Cattle, on the other hand, are foregut fermenters; feed enters the rumen where digestion occurs before it enters the intestine. This is much more efficient because digestive products can then be absorbed and further digested by the remainder of the digestive tract.

However, the horse’s need to run fast took a higher priority when the species evolved. Just think of the maximum speed of cattle (about 20 mph) versus horses (in excess of 40 mph in some breeds). It’s difficult to run fast if you have a very large stomach.

The most important point here is the horse’s gut has adapted to digest forage, so anything he eats can be transported down to the cecum in as little as three hours (this is remarkable, given the length of the average horse’s small intestine is 60-70 feet). That means a lot of concentrate that is fed, such as feeds that contain soluble carbohydrates (i.e., corn), is fermented by microorganisms in the colon rather than in the small intestine, which can more efficiently digest soluble carbohydrates. More importantly, concentrate feed in the colon is readily fermented, but it produces gas that can lead to colic.

Simply put, a horse’s diet should be based on forage, with concentrate supplemented as needed for energy requirements.

When horses are brought in from turnout, they like to have a meal, but the amount of concentrate can be minimized or horses can be fed an alternative source of forage, such as beet pulp or forage-based pellet feeds. For horses that eat too fast, particularly if the feed contains corn, large, smooth rocks can be placed in the feed bucket to make the horse work harder to get to the feed.

Another important component of diet management is selecting forage. It is possible to get away with feeding many types of forage. For example, coastal Bermuda hay is popular in the Southeast because it can be readily grown. There is nothing wrong with this type as hay, as long as horses are used to it and it is the best quality possible. Therefore, switching to Bermuda hay should be done slowly (over a week) by gradually increasing the amount of Bermuda hay, while reducing the current hay source.

Any rapid introduction of high-energy feed with soluble sugar content (sweet feeds, high-quality hays) can result in gas formation as intestinal microorganisms rapidly digest this material. Again, slow introduction of new hay or feed is the best way to avoid this.

Owners often are concerned or most knowledgeable about the protein content of the feed, but it is the energy content (in the form of carbohydrates) that is most important. It is fair to say that high- protein feeds often have high energy, but all common feeding methods (including using hay and concentrate) result in excess protein intake. This is not harmful unless the horse has a kidney condition, because most of the excess protein is excreted in the urine. This, again, goes back to the horse’s digestive tract.

Protein is well-digested by the small intestine, but in the horse it is moved down to the colon in a short period of time, and the colon cannot digest protein. Remember protein can be fermented, but at a much slower rate than carbohydrates.

Protein is also the most expensive component of any diet, so having an equine nutritionist balance the ration can be very helpful. Rations cannot be balanced correctly without knowledge of the amount (in weight) of each component of the feed. The amount of hay can be guessed fairly accurately by weighing some flakes and estimating, but the concentrate is difficult to estimate when given in scoops, rather than by weight. Supplements (such as vitamins) aren’t generally needed, but they also are not harmful. However, they add to the cost of feeding horses.

To get an idea of hay quality, just looking at and smelling the hay is very useful, but that doesn’t tell the whole tale. A feed analysis can be done, particularly for assessing the acid-detergent fiber content (ADF). An extension agent can be very helpful when assessing diet and management factors.

Water

A clean water source is vital to horse health, since horses need to drink approximately 1 L/hr (one quarter of a gallon) under normal conditions (low-level work in reasonable temperatures). This adds up to 24 L/ day, or 6 gallons. This also relates to the horse’s digestive tract, because horses secrete a tremendous amount of fluid into their intestinal tracts to facilitate movement of feed down the small intestine and fermentation in the colon.

Owners should monitor the amount of water their horses drink, because with reduced intake impaction becomes a concern. Not all horses want to drink as much as they need, so this might necessitate warming the water up in cold weather, or putting a little salt (a teaspoon) in their feed to encourage drinking. (If you notice excessive water consumption because the stall is soaked with urine, cut the amount.) Relying on ponds as a water source can be problematic, because some horses don’t like drinking from a pond, or the pond might contain stagnant water.

Other Considerations

It is important to make sure horses do not have other health issues, in order to avoid colic. For example, diseases that cause pain–particularly orthopedic and eye conditions–not only can cause horses to stop eating and drinking normally, but they likely also slow movement of food though the gastrointestinal tract because of their effects on nerves that stimulate the gut.

For example, a number of horses develop impactions because of orthopedic pain, and this is likely linked to nerves within the horse that inhibit intestinal movement. The mechanisms of these problems are not well-understood.

However, it has been determined that the normal horse will produce six to eight manure piles per day, and three piles or less puts a horse at significant risk of impaction. Therefore, horses that are painful, such as horses that are lame, should be examined and prescribed pain medications. The latter might include joint therapy drugs or use of non-steroidal anti-inflammatory drugs (NSAIDs) such as phenylbutazone.

Horse owners should be careful because excessive NSAID use can cause ulceration of the stomach or colon. A number of therapies might be needed to keep the horse comfortable without using potentially damaging NSAID levels.

Mares that have foaled are at risk of colic from colon twists. This might be because there is a lot of room left in the abdomen once the mare has foaled, or because the management of the mare changes once she has a foal. For example, mares need higher energy feed so they can produce milk, and they might be placed in a stall for longer periods of time.

Finally, a lot of people are concerned that weather changes cause colic. In all but one study, this has been disproved. However, it is worth going back to simple considerations over turnout, diet, and water consumption. It is possible that weather changes, such as a sudden cold snap, cause colic because horses drink less and are housed for greater lengths of time.

As a horse owner, I’d always go back to these basic management techniques to make sure they are as optimal as possible.