What Causes My Horse to Colic?

Colic simply refers to abdominal pain suffered by the horse.  It is also one of the most common ailments that horses suffer. In fact, up to 5% of all horses will suffer colic in any given year.

For horses under the age of 20, colic is responsible for 30% of all deaths. However, the majority of horses (~90%) survive just fine with timely intervention, so it’s important for horse owners to be educated and able to identify the signs of colic.

Due to its prevalence in horses, there have been many studies looking at types and causes of colic. A 10-year study published by the Western College of Veterinary Medicine in Canada evaluated 604 cases of gastrointestinal colic. The overall study found that colic was more common in geldings (50% of all cases) when compared to mares (30%) and stallions (20%). There was also a breed disposition where Quarter Horses and Thoroughbreds tended to have more bouts of colic compared to other breeds.  The most interesting data from the study were the types of colic suffered by the horses in the study. The most common types of colic included:

  • Large colon impaction (21%)
  • Large colon displacement (17%)
  • Spasmodic colic (12%)
  • Large colon volvulus (7%)
  • Lipoma (7%)

Large colon impaction colic was the most common type of colic seen in this study. Typically, in this type of colic, partially digested feed, usually forage, builds up in the large intestine. Other blockages, such as worms or sand, are also common. As time passes, the blockage builds and the feedstuff is no longer passing within the digestive tract, thus becoming “impacted.” Causes of impaction colic can be attributed to dehydration, parasitic infection (buildup of worms in digestive tract), ingestion of sand, or eating large meals of dry forage.

Large colon displacement happens when part of the colon rotates on itself, resulting in a blockage of the digestive tract. The colon is U-shaped in the horse and is quite mobile. Thus, when something like gas builds up within the colon, it can cause the organ to twist on itself. Gas can build up in the hind gut of the horse when they are overfed grain (concentrate). No other causes are directly linked to this type of colic.

Spasmodic colic is one of the more painful types of colic in horses. This is when the smooth muscle lining of the digestive tract starts to spasm, thus causing the pain. While no direct causes are known, it is thought parasitic buildup or recent deworming, stress, heavy physical activity, dietary changes or even drinking large amounts of cold water are all thought to be contributing factors.

Large colon volvulus is also often called “twisted gut.”  This is when a portion of the colon twists back on itself, causing a blockage of the digestive tract. Similar to large colon displacement, because the colon is U-shaped and mobile, a buildup of gas can cause the colon to twist. This is also seen in postpartum mares. Once the foal is born, the sudden extra room in the abdomen of the horse can predispose it to either colon displacement or this twisted gut condition.

Lipoma is when a tumor (usually benign) gets wrapped around the small intestine or small colon of the horse. This is most commonly seen in older horses, with an average age of 17 years old, whereas the average age for other types of colic was 7 years old. Exact causes are not known and it can affect thin or fat horses alike.

There are many other types of colic. However, those cited above are some of the most common types of colic suffered by horses worldwide. It is worth noting that in this study, these were horses brought to the veterinary school and were most often severe cases. Many sources cite impaction colic as the most common colic seen worldwide.

Some of the major contributors or causes of colic include:

  • Dehydration. See Is Your Horse Drinking Enough Water article for more information.
  • Rapid change of diet. See Safely Transitioning Your Horses Diet article for more information.
  • Stress. Overtraining, transport, postpartum and other stressors increase the chance of colic. See Tips to Decrease Colic Risk While Traveling for more information.
  • Poor dental health leading to less chewing and reduction of particle size of feed prior to swallowing. See Managing a Horse’s Dental Health article for more information.
  • Low quality forage.
  • Overfeeding concentrate. Always stick to 5 lb of concentrate or less per meal to avoid overloading the hindgut with starch, which can cause gas and other issues.
  • Recent deworming. Killing off large volumes of parasites (worms) can lead to impaction.
  • Putting feed out on sandy soils. It is always suggested to put feed in a feeder or on a feed pad.

Every horse owner needs to be aware of colic. It is also worth reading our other article, Is My Horse Colicing, to familiarize yourself with the signs and symptoms of a horse suffering from colic. If you are concerned about your feeding plan, please contact us for advice or to answer any of your questions!

The study quoted in this article is:
Causes of gastrointestinal colic in horses in western Canada: 604 cases (1992-2002)

Article By: Chris Mortensen, Ph.D.
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