Colic: Updates and Prevention

At the Healthy Horse Workshop held in Ft. Collins, Colo., on July 28, Nancy Loving, DVM, who owns Loving Equine Clinic in Boulder, Colo., addressed the audience of horse owners on the subject of colic. Her emphasis was on the importance of colic to all horse owners.

Citing statistics from the National Animal Health Monitoring System (NAHMS) survey, she noted that one farm out of every 10 will have about 2% of its horses experiencing colic. Also, 15% of fatalities in horses older than 30 days of age are attributable to colic. Her presentation focused on prevention methods to help horse owners keep their animals from becoming a part of these statistics, while also describing appropriate strategies to manage colic if it does occur.

Signs that indicate that a horse might be in abdominal distress include depression or anxiety-related behaviors like pawing, the horse looking at his sides, lying down, getting up, rolling, or displaying a general state of distress. A thorough veterinary examination helps determine the cause of these behaviors and also rules out other medical conditions such as tying-up, laminitis, pneumonia, or foaling difficulties.

An owner should collect information about a sick horse's vital signs and communicate this information to the veterinarian to expedite prompt medical attention.

There are myths related to colic treatment, such as needing to walk a colicky horse while awaiting arrival of the vet. A horse should be kept walking only if he persists in trying to roll or thrash and is a danger to itself or humans. A horse that lies quietly can be allowed to do so. Loving has found over the years that when it is first noticed that a horse has colic, it is valuable to trot him vigorously on the longe line for about 15 minutes to see if that will ease pain from a gas or spasmodic colic, keeping in mind that a horse with a muscloskeletal problem might not be amenable to forced exercise.

A trailer ride has been known to jiggle the bowel to achieve similar relief for a simple colic.

Non-steroidal anti-inflammatory medications (NSAIDs) such as phenylbutazone (Bute) or Banamine should not be given until first discussing your horse's case with your veterinarian. These drugs are capable of masking the pain of a surgical condition and might delay appropriate treatment. In addition, a horse with intestinal stasis and poor motility might not absorb oral medications sufficiently to provide a therapeutic advantage when intravenous administration would work better.

A veterinarian will perform a thorough physical exam and implement medical therapy and pain relief. In some cases, treatment might include administration of ample IV fluids to increase fluid volume in the bowel; over-hydration of the intestinal tract and its circulation improves blood flow and motility that might relieve an impaction or return a mild displacement to normal.

In the event that a horse does not respond to medical therapy in a reasonable time, the horse should be shipped to a referral hospital for further diagnostic workup and possible surgery. Abdominal ultrasound, abdominal fluid analysis, and blood analysis are helpful to perform at a referral hospital to gain as much information as possible about your horse's condition. In addition, precautionary steps will be taken to protect against laminitis, a possible side effect of severe colic.

Preventing colic is better than treating colic. Many current colic prevention strategies counter what has previously been believed as the "way" of administering horse care. Research and science have proven that what has been done in decades past is counterproductive to the best management practices for equine intestinal health.

Practical measures rely on altering feeding practices; for example, limiting the amount of grain fed--too much grain is known to disturb intestinal health. A pound or two a day is not necessarily problematic provided a horse also has access to 15-20 pounds of hay per day (for the average 1,000-pound horse), but in general, grain or concentrates should not be the first choice in nutritional options. Optimal fiber digestion occurs in the large intestine, but grain is processed mostly in the small intestine, yet it is incompletely digested there. This results in passage of excess starch into the large intestine, where it is poorly processed, thereby creating an environment that kills normal intestinal bacteria, with the potential to release endotoxin into the circulation.

Grain also amplifies acid production in the stomach, increasing the likelihood of development of gastric ulcers, especially when horses are fasted for long periods between feedings. A horse with ulcers might suffer intermittent bouts of colic, or might be reluctant to work or is lackluster in performance.

Another common sign of ulcers is poor appetite in spite of weight loss. Ulcers occur in up to 93% of highly stressed horses (racehorses, high-level show horses) and 60% of average riding horses or less-intense show horse.

Risk factors for ulcers include stress of any kind, such as transport, illness or injury, dehydration, confinement, or social competition in a herd. NSAIDs (phenylbutazone or Banamine) are notorious in their propensity to induce gastric ulcers.

Not all risk factors can be controlled, but offering free-choice hay and substituting grains with feeds such as soaked beet pulp, high-fat rice bran, or vegetable oil can reduce the risk of developing gastric ulcers.

Digestive efficiency can be altered by feeding. Grain ingestion reduces the fluid content of the bowel by 15%, and control of a horse's daily caloric intake means that a grain-supplemented horse is offered less hay. Yet, fiber is an essential component of intestinal health, and it also serves as a fluid reservoir in the bowel.

The common practices of keeping horses in stalls for a large portion of the day and feeding large meals only twice a day wreaks havoc with digestive health; stall confinement increases the risk of colic by at least 50%. Intestinal motility is reduced by confinement and by fasting between large meals. With reduced intestinal motility comes the risk of impaction colic or gas distention.

The best strategy for minimizing colic is to offer free-choice grass hay so a horse can "graze" intermittently through the day, and to limit grain, while providing daily turnout and regular exercise.

Other causes of colic--such as sand ingestion--are often related to restricted access to hay. Restriction of fiber and/or boredom that induces a horse to nibble at scraps of hay and dirt increase risk of accumulation of sand in the bowel. The best prevention for sand colic is to feed ample hay, and when possible, use feeders (like large tractor tires) to confine the hay and keep it from being strewn across the ground. Many commercial feeders do not accomplish this end, so sand ingestion might not be prevented entirely--it is recommended to feed psyllium for a week each month to move through any sand that has collected.

Obesity and parasites also are risk factors for colic, but a conscientious owner can prevent and manage these concerns. A horse should be fed by weight, not volume, since the density of hay varies from bale to bale. Horses should be pastured on non-irrigated, dryland pasture when possible. If the only pasture option is a rich, irrigated field, then many problems, including obesity, can be avoided by fitting a horse with a grazing muzzle or by limiting turnout time. This prevents intake of highly fermentable, rich grass that can contribute to gas or spasmodic colic episodes.

Tapeworms have been identified to cause as many as 22% of spasmodic colic cases. Parasite control is managed with regular deworming schedules of the appropriate anthelmintics. Manure that is cleaned up at least twice a week limits development of other infective parasite larvae in areas where the horse might eat. Pasture rotation limits overgrazing and facilitates ultraviolet kill of remaining infective larvae.

Here is an ideal situation to minimize colic:

  • Feed at least 60% of the daily ration as forage (hay or pasture);
  • When possible, pasture in non-irrigated fields, and/or use a grazing muzzle to control weight and intake of rich forage;
  • Limit grain to as little as possible; none is preferable;
  • Substitute high-fat feeds and high-fiber feed for grain supplements when more calories are needed;
  • Provide feeding systems that limit the intake of sand and dirt;
  • Provide plenty of turnout and exercise each day;
  • Provide clean, ice-free drinking water;
  • Implement regular and frequent deworming programs for the herd;
  • Implement a herd health program of preventive care;
  • Minimize stress (transport, herd dynamics, housing, illness, injury) as much as possible.

About the Author

Nancy S. Loving, DVM

Nancy S. Loving, DVM, owns Loving Equine Clinic in Boulder, Colorado, and has a special interest in managing the care of sport horses. Her book, All Horse Systems Go, is a comprehensive veterinary care and conditioning resource in full color that covers all facets of horse care. She has also authored the books Go the Distance as a resource for endurance horse owners, Conformation and Performance, and First Aid for Horse and Rider in addition to many veterinary articles for both horse owner and professional audiences.

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