Understanding Colic

By Sarah Gee
©Voice, November 2005

If you’re a horse owner, chances are you’ll have to, at some point, deal with colic. Colic is the number one killer of horses. It has a myriad of causes and a variety of symptoms. It is among horse owners’ worst nightmares. However, there are ways to reduce the risk of and treat colic.

What is colic?
First, one must understand the term. Colic is not a disease; it is merely a term used in reference to a condition of pain. Specifically, colic refers to abdominal pain most often originating from the digestive tract. In other words, when someone says their horse has colic they’re basically saying that their horse is feeling pain in its abdomen.

The American Association of Equine Practitioners classifies colic in horses into three groups - intestinal dysfunctions, intestinal accidents, and enteritis or ulcerations. Intestinal dysfunction, the most common category, simply means that the horse’s bowels are not working properly. Intestinal dysfunction can be caused by gas distention, impaction, spasms, and paralysis. Intestinal accidents occur less frequently and include displacements, torsions, and hernias, whereby sections of the intestine become trapped or pinched in the body cavity. The term “Twisted Gut” is often used in these cases. Intestinal accidents almost always require emergency surgery. Enteritis or ulcerations are colics related to inflammations, infections, and lesions within the digestive tract. They can be caused by numerous factors including stress, disease, salmonellosis, and parasites.

Common colic culprits
As stated above, the causes of colic are myriad. The following is a list of some of the most common culprits.

• Parasites
• Over consumption of high energy feeds that change the
environment in the digestive tract.
• Abrupt changes in the physical or chemical form of the diet.
• Side effects of certain medicines.
• Ingesting poisons, toxins, mold, or other materials that
do physical damage to tissue or change the normal
environment of the digestive tract.
• Stress caused by changes in housing, transportation, or daily routine.
• Sand impaction – ingestion of sand my occur when being fed
off the ground or when the horse has a craving for an
unnatural substance.
• Enterolith formation or formation of a mass in the large
intestine that results in an obstruction. May be due to
consumption of foreign materials such as wire, nails, or
fencing material, which serves as an object of origination for
concretion or stone formation.
• Inadequate water consumption.
• Poor quality feeds.

Why do horses colic?
So, why are horses so prone to colic? Well, a brief tour of the horse’s gastrointestinal tract provides the answer. Once chewed, food passes down the esophagus into the stomach. The horse’s stomach is small, holding only about 9 – 16 quarts. After a period of digestion in the stomach, food passes into the small intestine, which is approximately 72 feet in length with a diameter of 3 – 4 inches and a capacity of 10 – 14 gallons. The majority of the small intestine hangs from a curtain-like membrane called the mesentery. The mesentery is attached to the body wall at one point in the middle of the abdomen under the spine. The caecum, a large blind-ended outpouching over 3 feet long with a capacity of 6 – 8 gallons, rests at the junction of the small and large intestines. Food passes from the small intestine into the caecum before passing into the large intestine. Together, the caecum and large intestine form the horse’s “fermentation chamber,” allowing it to gain nutritional support from the complex carbohydrates contained in grasses and other forage. With a length of 10 – 13 feet, a diameter of 8 – 10 inches, and a capacity of over 13 gallons, the large intestine fills a significant part of the abdomen. Surprisingly, this large, unwieldy structure is tethered to the body wall at only two points – at its beginning (where it joins the small intestine and caecum) and at its end (where it joins the short, narrow small color which leads to the anus).

As the preceding tour suggests, there are a number of areas in the horse’s digestive tract that have the potential for problems. The small stomach can be easily overloaded. That coupled with the horse’s inability to vomit, predisposes the horse to stomach rupture. The small stomach can also be ruptured by the build up of gas. The small intestine is only connected to the body wall by the mesentery, which is only attached at one point. This means that the small intestine can easily move around or fold over and become trapped or pinched.

The length of the small intestine requires it to make numerous turns, turns in which blockages may occur. The blind-ended caecum sits in a position that makes it prone to blockages as food passes in and out. Like the small intestine, the large intestine is primarily free in the body cavity (attached only at its beginning and end), making it ripe for twists and folds. Also, the way it lays in the body cavity, in a double U formation with one U stacked on top of the other, means that food must travel through a number of 180-degree bends. Those bends are prime locations for blockages. Finally, the narrow diameter of the small colon makes it a likely site for impaction as food leaves the relatively wide large intestine.

Reducing the risk
Ok, we have the common causes and an understanding of why colic is so prevalent, now we need to know what we can do to reduce its incidence. As in all things equine, management is key in reducing the risk of colic and, although not all cases are avoidable, the following guidelines can maximize a horse’s health and make it less prone to colic.

• Establish a daily routine, including feeding and exercise.
• Feed a high quality diet comprised primarily of roughage.
• Avoid feeding excessive grain and energy-dense supplements.
• Divide daily rations into two or more smaller feedings.
• Feed hay free choice.
• Set up a regular parasite control program.
• Provide exercise and/or turnout every day.
• Make changes to exercise regimens gradually.
• Provide fresh, clean water at all times (except when the horse
is excessively hot).
• Avoid putting feed on the ground, especially in sandy soils.
• Check hay, bedding, pasture, and environment for potentially
toxic substances such as blister beetles, noxious weeds, etc.
• Reduce stress – pay special attention to horses when
transporting them or changing their surroundings, such as at shows.

Recognizing colic
Of course, not every case of colic is preventable so the next thing that needs to be covered is how to tell if your horse is suffering from colic. There are numerous indications that a horse has colic. Usually, a horse will show only a few signs during an episode of colic. Seeing any of the following signs should prompt you to take a closer look and keep a watchful eye on your horse.

• Turning the head toward the flank.
• Pawing
• Kicking or biting at the abdomen.
• Stretching out as if to urinate without doing so.
• Repeatedly lying down and getting up or attempting to do so.
• Rolling, especially violent rolling with grunting sounds.
• Sitting in a dog-like position or lying on the back.
• Lack of appetite
• Putting the head down to water without drinking.
• Lack of bowel movements.
• Absence of, or reduced, digestive sounds.
• Sweating (unrelated to exercise or hot weather)
• Rapid respiration and/or flared nostrils (unrelated to exercise).
• Elevated pulse rate (greater than 52 beats per minute).
• Depression
• Lip curling (unrelated to sexual interest)
• Cool extremities
• Holding the head in an unusual position.

In general, the more obvious the signs of pain, the more serious the problem. Also, in horses with serious conditions, the signs of pain usually persist and may even worsen with time, whereas in horses with mild colic, the signs of pain may be intermittent or may disappear after a short time.

What to do
While a number of colic cases do resolve without medical attention, a significant percentage do require prompt medical care that may actually include emergency surgery. If you suspect your horse is suffering from colic, the following is the best-suggested plan of action.

1. Remove all feed and water.
2. If necessary, move horse to small enclosure so you see him better.
3. If it’s dark, arrange for lighting.
4. If the horse just wants to stand, allow him to do so, if he’s
rolling or in danger of hurting himself, walk him around but
do not tire him out.
5. Call your veterinarian and be prepared to supply the following –
• Specific signs of colic and their severity
• Pulse rate – measured over the heart (just behind the left
elbow) or over an artery (at the sides of the fetlock or on the
underside of the lower jaw)
• Respiratory rate (breaths per minute)
• Rectal temperature
• Color of gums
• Moistness of gums
• Capillary refill time (tested by pressing on the gums,
releasing, and counting the seconds it takes for color to return)
• Digestive sounds (if any)
• Bowel movements, including color, consistency, and frequency
• Any recent changes in management, feeding, or exercise
• Medical history including deworming and any past bouts of colic

After hearing this information, the veterinarian will decide on a course of action. Follow his advice. Do not administer any drugs to the horse unless specifically directed to do so by your veterinarian.

6. Keep a close eye on the horse until the signs of colic resolve
or the veterinarian arrives.

Treatment
Veterinary treatment of colic can be categorized as medical or surgical. Routine medical procedures include the passage of a nasogastric tube, rectal examination, accessing vital signs, and administering medications for sedation , pain relief, and laxatives. Complex medical procedures include hospitalization for laboratory tests including blood samples and abdominal fluid samples, and supportive therapy and medications. Surgical procedures can involve the positioning of a displaced section of intestine, manipulating an obstruction, decompressing a gaseous formation, removing a diseased or compromised section of intestine, or removing the contents of the stomach, ceacum, or intestine.

In conclusion
The key to minimizing the incidence of colic is good management. The key to minimizing the impact of colic is to identify the problem early and call your veterinarian immediately. Treat every episode of colic as potentially serious and involve your veterinarian from the outset; try never to jeopardize your horse’s health for the sake of a few dollars.

References:

Can You Prevent Colic
www.xcodesign.com/aaep/displayArticles.cfm?ID=24

Colic in Horses,
University of Kentucky Cooperative Extension Service publication #ASC-128

Colic: Minimizing its Incidence and Impact in your Horse www.xcodesign.com/aaep/displayArticles.cfm?ID=25

Colic Prevention Tips
www.xcodesign.com/aaep/displayArticles.cfm?ID=191

The Colic Fact Sheet
www.equusite.com/articles/health/healthColicFacts.shtml

Understand Colic in Horses
by David W. Freeman, PhD and Carolynn MacAllister, DVM.
Oklahoma Cooperative Extension Service publication #F-3921