Colic Can be a Real Pain!

Too much grass...too much grain...mouldy feed or grain...rapid change from one feeding program to another.

Twists, blockage, gas, dehydration, ulcers, disease. And what about those horses that seem to colic every time the barometric pressure drops?

Suffice it to say that, for almost every foot of the horse's long and complex gastrointestinal system, there's a factor that can throw normal digestive function into serious disarray. The usual result: colic, the most common equine ailment and the subject of numerous frantic calls from horse owners to veterinarians.

What is colic?

Colic is a catch-all term used to describe abdominal discomfort from any cause. Signs of colic include pawing, kicking at the belly, looking at or nipping the flanks, rolling, sweating, or straining as if to pass urine or feces. Pain may be mild or severe, constant or intermittent.

If these signs are noticed, the best plan is to keep the horse from eating and to call a veterinarian immediately. 'Waiting it out' to see if the horse recovers on its own is almost always a bad decision, as there is no way for an owner to determine in the beginning stages how colic will progress. With early intervention by a veterinarian, the cause can usually be determined and proper treatment can be started.

A complex digestive system

Any discussion of colic needs to start with a brief tour of the horse's stomach and intestines. For such a large animal, the equine stomach is quite small and can easily be overfilled to the point of discomfort. The only natural way to relieve a full stomach is for ingested material to move into the small intestine where starch digestion takes place.

If grain meals overwhelm the capacity of the small intestine, undigested starch flows into the hindgut. This area of the digestive tract is the site of fibre fermentation, and an influx of carbohydrate plays havoc with normal function. Microbial balance goes awry, gas production rises, and pH levels swing away from normal.

Distention, obstruction, or malfunction in any part of the digestive tract may cause the discomfort we know as colic. Problems in the stomach account for about 12% of colic cases; the small intestine is the culprit in about 33%; and hindgut malfunction causes the remainder, about 55%.

While colic can result from a number of factors, feeding practices are among the most common causes and are probably the easiest for an owner to control. Consideration should be given to overall feed management as well as the forage and concentrate portions of the diet.

Fundamentals of forage

The horse's digestive system is designed to process a steady supply of forage. Grasses and legumes, whether fresh in the pasture or dried as hay, are staples of the basic equine diet. However, horses can get into trouble if they are offered too little, too much, or the wrong kind of forage.

Horses in training are sometimes given limited forage, often much less than the daily 1.5% to 2% of body weight that is suggested. This practice results in a stomach that is frequently empty, a situation that may lead to discomfort from gastric ulceration. Too much forage, especially in the form of fresh grass, might cause colic or other metabolic problems. Especially in the spring but also after periods of rain in the fall, lush grass provides a high carbohydrate level that may exceed the digestive capability of the intestinal tract. Carbohydrate levels are also high in some types of hay.

Forage that is extremely stemmy or tough can present a different problem. Horses on overgrazed or poor-quality pasture may ingest brushy weeds that are dry and hard to chew, and a surprising number of equines are eager to gobble their lignin-rich straw bedding when they've finished their hay. Hay that contains weeds and heavy stems can also cause problems. The chief danger with this type of inferior forage is impaction, a blockage of the digestive tract with resultant pressure, pain, and the possibility of tissue damage.

Wetter is better

Sufficient water intake is essential to digestion and the smooth passage of ingested material through the gastrointestinal system. As a general rule, horses require about 38 to 45 litres of water per day; the amount can vary with exercise and climate.

Limiting the horse's access to fresh, clean water for even a few hours greatly increases the risk of colic, as dehydration can lead to impacted food masses that block the intestine. When fluid access is limited, such as when the horse is traveling or competing, owners should remember to offer water frequently, even if the horse doesn't seem interested. Here's a travel tip: offer water at the end of the driver's rest stop or coffee break instead of immediately after coming to a halt. Horses often drink more willingly after standing still for a few minutes.

Horses frequently refuse to sample water that's different from what they're accustomed to; on short trips, taking a supply of water from home may encourage them to drink. Very cold water seems to discourage drinking. However, water intake is essential during winter months, and providing warmed (not hot) water may encourage horses to drink.

Grain, a mixed blessing

The demands of training and performance call for more calories than can easily be supplied by an all-forage diet. Fed at the level of 0.5% to 1% of the horse's weight per day, grain products are generally safe and useful additions to the equine diet, providing energy and boosting quantities of protein, vitamins, and minerals. However, horses that require large amounts of grain are at increased risk for colic.

Studies indicate grain feeding at 2.5 to 5 kilograms per day increased the odds of colic 4.8 times over horses given no grain, and the risk rose to 6.3 times for horses eating more than 5 kilograms daily, according to an article by Kentucky Equine Research president Joe Pagan. His recommendation is to divide a horse's daily grain ration into several small feedings of no more than 2.2 kilograms each to avoid stressing the digestive tract.

Make changes slowly

Avoiding sudden changes in any aspect of feeding is one of the most important things for stable managers to remember. With any change, the microscopic intestinal organisms that aid digestion must be allowed to adapt to the new feed. Once a feeding schedule (products, amount, time of feeding) is established, it should be followed with as little variation as possible.

Studies have shown an increased risk of colic when even small changes are made to what a horse eats. To avoid problems, carry out any changes in the type of feed or hay gradually over a period of five to ten days. Begin by mixing a handful of new feed into the old ration, increasing the new product slightly every day until the switch is made. A new type or batch of hay should be introduced the same way, beginning by offering a small amount of new hay with several flakes of old hay and then gradually blending larger amounts of new hay into the diet.

Changes in the amount of feed, hay, or grazing time should be made little by little as well. Suddenly doubling a horse's grain ration to help him gain weight is asking for trouble. Likewise, bringing a pasture-kept horse into the stable 24 hours a day or moving a stable-kept horse onto free-choice pasture can easily result in digestive problems. Begin with an hour or two per day of the new management, increasing by small increments. As a safeguard, offer extra hay in the stall before turnout time so the horse will not enter the pasture with an empty stomach.

If you own or manage horses for any length of time, sooner or later you're almost guaranteed to encounter colic. Attention to proper feed management can minimize the frequency of problems, and rapid veterinary intervention can often put your horse back on the road to health.

By Kentucky Equine Research - Last updated 16 November 2012