Roughly 15% of colic cases will require surgery, which can be highly successful with timely referral and skilled surgeon

by Gregory Beroza, D.V.M.

THE WORD colic puts fear into the hearts of the toughest and most seasoned horsemen. Colic can be considered the proverbial equine equivalent of a human heart attack in its unexpected occurrence, its need for immediate veterinary attention, and the unpredictability of its outcome.

Colic is probably the number-one premature cause of death in horses. It affects all breeds, uses, ages, and genders. It occurs on the best- and worst-managed horse farms, and it can bring the strongest horse down to its knees in seconds.

But regardless of the best management, colic can be an unexpected and fatal pathologic occurrence. It is rare that a seasoned equine professional has not had a horse affected by a significant episode of colic at some time in his or her career.

Roughly 85% of colics are manageable with proper medical support. The other 15% are in need of surgical intervention.

Colic surgery first became possible in the early 1960s. Until the early 1980s, the anticipated surgical success rate for colics at the average surgical facility was only about 30%. Today, a competent surgical hospital should deliver about a 90% success rate, if the referrals are timely and appropriate.

The best place for a colicky horse, especially if the bout has lasted more than a few hours, is a fully equipped equine hospital with appropriate surgical capabilities. Early recognition, prompt referral, and competent care are the three most important factors in effecting a successful outcome.

Types of colic

The first action horsemen should take when confronted with a case of colic should be immediately to take away the horse's food and water until details of the cause of colic can be determined.

Spasmodic colic is simply a temporary interruption of the normal digestive tract's progressive downstream motility patterns. It can occur for a multitude of interrelated reasons, such as sickness, dehydration, electrolyte imbalance, infection, and more commonly, parasitic larval migration. Parasite larvae migrate throughout the year; however, they tend to show the greatest activity during the seasonal changes of both spring and fall. These times, too, are coupled with the greatest changes and inconsistencies in nutritional management, feeds, and weather. The early lush spring pastures are one situation to properly monitor; just as important is the early winter loss of pasture, coupled with the increased winter diet of drier stored hays.

Spasmodic colics can be temporary and self-limiting, or they can signal the beginning of a tailspin, inevitably requiring surgical intervention.

Simple spasmodic colics can be responsible for the horse's initial ineffective ability to purge itself of the gases of digestion and fermentation, which are constantly produced. This can lead to gas colic. These types of colics are the most responsive to an early therapeutic trailer ride. (Some cases of colic have been observed to resolve themselves when the horse is loaded onto a trailer or van and hauled down the road.) However, if colic is bad enough to warrant a therapeutic trailer ride, the destination should be an appropriately equipped equine hospital in relative proximity rather than returning the horse to the home farm one hour later, only to find that the therapeutic trailer ride did not work.

Lunging also may be effective in expelling gas and even relieving spasmodic colic.

None of these simple therapeutic options should be carried out, nor should medical treatment be given, without at least first informing your attending veterinarian that you have a horse that is colicking and your projected plan of care.

Impactions are among the most common and usually the most successfully treatable forms of colic. They usually affect the pelvic flexure portion of the large bowel, where it proportionately has its most narrow diameter, complicated by a restrictive physical turn in the digestive tract. However, obstructions can occur at any point within the digestive tract.

Impactions can be caused by a multitude of spasmodic conditions that limit normal digestive motility, coupled with constipation due to a significant dietary change (usually to a more dry and coarse hay), limitations in water intake, or both. Treatment options are aimed at calming the discomfort, decreasing the spasms, hydrating the horse systemically with intravenous fluids and/or oral fluids, and lubricating the digestive tract with mineral oil.

It is not good practice to administer mineral oil through a nasogastric tube to a horse without confirming it has an impaction. Later surgical correction and even a more rapid physical deterioration can be the end result of inappropriate oiling. In fact, no colic should be treated as a simple impaction without a proper diagnosis first, because without a proper diagnosis, more serious, life-threatening conditions could be missed, improperly treated, or both.

Proper evaluation for colic includes a physical examination, recording the heart rate and degree of digestive motility, passing a nasogastric tube to identify if any fluid is already built up in the upper digestive tract, and the most important finding, rectal examination.

Digestive shutdown

Total loss of normal digestive motility is referred to as ileus, which can be temporary and correctable or it can be permanent and ultimately fatal. Ileus can be a secondary result of a simple spasmodic colic; it can be a progressively developing result of either a physical or a physiologic obstruction; and it can be an end result to even the most straightforward of surgical corrections. Ileus cannot totally be prevented, but it can be managed, and its occurrence can be decreased with proper precautionary care. Patients can be lost to ileus subsequent to an initially successful surgery.

Obstructions can be physical, as with an impaction or a twist, or they can be physiologic and of equally significant consequences. Dead bowel from a shower of blood clots due to parasitic larval migration, from a twist, or from a strangulating tumor (lipoma) must be removed surgically, and the sooner the better.

Small portions of less than 50% of the involved bowel can be removed successfully (resection) and the healthy sections can be reattached (anastomosis). Unfortunately, when a horse has larger amounts of devitalized bowel, euthanasia is the only sensible option. Removal of too much bowel could make the horse a digestive cripple, thereby committing it to a lifelong special feeding program, potential significant weight loss, and unthriftiness.

The amount of damage to the local blood vessels and the circulatory system are the defining prognostic parameters that can lead to bowel necrosis (tissue death), enteritis,  and circulatory shock. Again, major surgical intervention and diagnostic evaluation are most successful with prompt referral and immediate attention.

Successful surgeries

Horses have undergone major, radical, surgical interventions and have successfully returned to every type of previous activity from racing to breeding. Even foals or yearlings affected prior to their racing careers later have performed to maximal expectations. For example, Lil E. Tee underwent a bowel resection prior to entering training, and he went on to win the 1992 Kentucky Derby (G1).

Surgical intervention for colic in a pregnant mare is now a common procedure. The fetus, like its anesthetized mother, will sleep during the surgery and have no long-term post-surgical complications. Fortunately, with today's safe general anesthetic agents, pregnant mares can be operated on without major risk to the survival of the fetus. It is rare for a colic surgery to contribute to a dystocia weeks or months later, although it is possible. Rather, it is the uncorrected colic that is the more significant problem for both the mare and her unborn foal.

While regard for the foal's well-being is taken very seriously, colic surgery is intended first and foremost to save the mare's life; if the mare does not survive, obviously neither will the fetus.

Adverse outcomes

Earlier prejudices held that horses having undergone colic surgery had a greater incidence of a second colic episode or need for surgery. These views are dissipating in favor of the opinion that a horse may have another unrelated colic episode. However, there are unique exceptions. Some broodmares have a tendency to repeatedly displace their large bowels, for which select surgeons have developed and sometimes perform a permanent surgical correction. However, poorly managed horses and horse farms have a higher incidence of needing surgery again, especially if the pre-existing situations that caused the horse to colic are not corrected.

Some horses previously operated on for colic can be affected later by adhesions, bands of scar tissue that bind together two anatomic surfaces that normally are separated from each other, thereby causing the horse to colic again. This also can be the case with the post-surgical complication of peritonitis, which is an inflammation of the membrane that lines the inside of the abdomen. However, the onset of peritonitis usually is rare following surgery performed by a skilled surgeon.

It is important for an experienced surgeon to properly select those horses for surgery that have a reasonable chance of leading a normal life and having an uneventful post-surgical recovery. Equally important, a horse that the surgeon determines during surgery not to have a reasonable chance for a normal post-surgical life should be considered not to be recovered; that is, the horse should not be brought out of anesthesia. Post-surgical complications for horses with major gastrointestinal problems can be significant, such as peritonitis, toxemia, and laminitis. It can be more humane not to wake up horses in this unfortunate category.

Post-operative care

Recovered horses usually require several post-surgical days, if not a couple of weeks in the hospital, to get intensive supportive aftercare and to receive optimal medical therapy. Horses often are not fed any solid matter until a few days after surgery because their digestive tracts can be prone to decreased motility during this period. Horses are hydrated intravenously with electrolyte fluids, and after two to three days, they slowly are introduced to oral water and often given just mouthfuls of fresh grass. Administration of antibiotics also is necessary. By the third day, small amounts of loose mashes are fed, and wet hay can be fed a couple of times a day. Most horses are back to a reasonably normal feeding of moistened feed within the first week after surgery. 

Most surgeons place a full belly bandage on the horse after surgery that is replaced approximately every week, or as needed.

Minimize colic hazards

Optimal management is paramount to decrease the incidence of colic, promptly recognize its presence, and expeditiously act in the most appropriate manner to produce a better final outcome. Changes in diet, stabling, weather, and management routines often can precede bouts of colic. Consistency in feeding programs and other healthcare issues also minimizes the incidence of colic.

Dental problems can contribute to a horse's inability to properly chew or digest feeds, which causes the fiber size to be too bulky to pass easily through the intestinal tract. If a horse has an episode of impaction colic, a good policy is to have a veterinarian check its teeth after the colic is resolved and perform dental care if needed.

Having a proper deworming program in place is necessary, but it is no guarantee against ever having colic. Better understanding of the life cycles of parasites and new medications have enabled elimination of pathologically migrating larvae rather than simply eliminating the adult parasites.

Dewormers have been introduced recently that successfully eliminate tapeworms, which previously had been underestimated as a cause of colic.

Use of phenylbutazone, a nonsteroidal anti-inflammatory drug (NSAID), in too high a concentration or used too often also can lead to gastritis, colic, and gastric, duodenal, and oral ulcers. NSAIDs should be used prudently, and if they are suspected to be causing a problem, the horse should be treated with omeprazole (GastroGard), cimetidine, ranitidine, or other appropriate medications.

Stress can be one of the most significant contributory causes of colic. For more information on this subject, see "Stress, colic, and baseball" in the April 30, 2005, issue of Thoroughbred Times.

Gregory Beroza, D.V.M., is a board-certified surgeon and practitioner. He is director of the Long Island Equine Medical Center in Huntington Station, New York, and he has an office at Belmont Park. He often writes articles under the title HorseDoc Reports. His website is www.horsedoc.com