This list of types of horse colic is not exhaustive but details some of the types which may be encountered.
This is most likely to occur in horses that graze sandy or heavily grazed pastures leaving only dirt or sand to ingest. The term sand also encompasses dirt. The ingested sand or dirt accumulates in the pelvic flexure, right dorsal colon and the caecum of the large intestines. As the sand or dirt irritates the lining of the bowel it can cause diarrhea. The weight and abrasion of the sand or dirt causes the bowel wall to become inflamed and can cause a reduction in colonic motility and in severe cases even peritonitis. Horses should not be fed from the ground in areas where sand, dirt and silt are prevalent although small amounts of sand or dirt will still be ingested by grazing.
These are round balls of mineral deposits often formed around a piece of ingested foreign material, such as sand or gravel. When they move from their original site they can obstruct the intestine. They are not a common cause of colic in horses, but are known to be more common in states with a sandy soil and where an abundance of alfalfa hay is fed, such as California. Once a horse is diagnosed with colic due to enterolith it usually requires surgery to correct the condition.
Pelvic flexure impaction
This is caused by an impaction of food material (Grass, Hay, Grain) at a part of the large bowel known as the pelvic flexure of the left colon where the intestine takes a 180 degree turn and narrows. Impaction generally responds well to medical treatment, but more severe cases may not recover without surgery. If left untreated, severe impaction horse colic can be fatal. The most common cause is when the horse is on box rest and/or consumes large volumes of straw, or the horse has dental disease and is unable to chew properly.
Occasionally there can be an obstruction by large numbers of roundworms. This is most commonly seen in young horses as a result of a very heavy parasite infestation that can subsequently cause a blockage and rupture of the small intestine. Deworming heavily infected horses may cause dead worms to puncture the intestinal wall and cause a fatal peritonitis. If a heavy worm infestation is suspected. It is often the result of a poor deworming program. Horses develop immunity to parascarus between 6 months age and one year and so this condition is rare in adult horses.
Left dorsal displacement
Left dorsal displacement is another of the physical horse colic types where the left dorsal colon becomes trapped above the spleen.
Right dorsal displacement
Right dorsal displacement is another displacement of part of the large bowel. Although signs of this horse colic may not be very severe, surgery is usually the only available treatment.
Various parts of the horse's gastrointestinal tract may twist upon themselves. It is most likely to be either small intestine or part of the colon. Occlusion of the blood supply means that it is a painful condition causing rapid deterioration and requiring emergency surgery.
Intussusception is a form of equine colic in which a piece of intestine "telescopes" within a portion of itself. It most commonly happens in the small intestine of young horses and requires urgent surgery.
Spasmodic colic is the result of increased peristaltic contractions in the horse's gastrointestinal tract. It can be the result of a mild gas buildup within the horse's digestive tract. The signs of this horse colic are generally mild and respond well to spasmolytic and analgesic medication.
Horses form ulcers in the stomach fairly commonly. Risk factors include confinement, infrequent feedings, a high proportion of concentrate feeds, excessive non-steroidal anti-inflammatory drug use, and the stress of shipping and showing. Most ulcers are treatable with medications that inhibit the acid producing cells of the stomach. Antacids are less effective in horses than in humans, because horses produce stomach acid almost constantly, while humans produce acid mainly when eating. Dietary management is critical. Bleeding ulcers leading to stomach rupture are rare.
Other causes may show clinical symptoms of colic in horses. Strictly speaking colic refers only to signs originating from the gastrointestinal tract of the horse. Signs of equine colic may be caused by problems other than the GI-tract.