Colic is a general term used to describe abdominal pain in the horse. There are many different kinds of colic such as:
1) Sand colic – Horses can ingest sand when they eat hay or grain off of sandy ground. The sand settles out of the GI contents and accumulates in their large colon. The sand grates against the inner lining of the large colon causing irritation. This irritation can lead to mild, intermittent colic episodes and loose manure. Your veterinarian may be able to hear this sand accumulation during his/her physical examination. You may also perform a sand test.
2) Gas colic – Gas can accumulate in a horse’s GI tract and the distension of the intestine causes abdominal discomfort. Gas colics are usually mild and are usually responsive to Banamine therapy. A sudden change in diet may cause an increase in gas production within the intestine and increase the frequency or severity of gas colic.
3) Impaction – Feed may become impacted (unable to move) within the GI tract, most commonly the large colon portion. Horses are more likely to develop impactions when they do not have access to fresh, unfrozen water or if they are not drinking as much water as they should. Your veterinarian may be able to feel an impaction on rectal examination, although it may be located in a section of intestine out of his/her reach.
4) Right dorsal colitis – The right dorsal colon is a segment of the large colon of the horse. This portion of the GI tract is most sensitive to NSAIDs such as phenylbutazone (Bute) or flunixin meglumine (Banamine). Cases of right dorsal colitis are most commonly associated with very high doses of an NSAID, but some horses are more sensitive than others. Horses with right dorsal colitis will show signs of abdominal discomfort and may have diarrhea and/or edema (fluid accumulation) in their lower limbs and under their chest/abdomen. An abdominal ultrasound will help your veterinarian diagnose this condition.
5) Gastric Ulceration – Horses in high-stress situations are predisposed to developing ulcers in their stomach lining. High-stress situations include frequent travel, showing, heavy training, and limited/no turn-out. These ulcers in the stomach lining can be very painful and horses may show this discomfort by acting colicky, grinding their teeth, eating grain meals slowly or refusing grain, being “girthy”, or performing poorly. High doses of phenylbutazone (“Bute”) can also cause serious gastric ulceration. An endoscopic examination is the only way to definitely diagnose ulcers. A change in management of horses with gastric ulcers coupled with medications to treat and prevent gastric ulcers can provide significant relief.
6) Large colon displacement/volvulus – The horse’s large colon is only attached to the body wall in one location and therefore is very mobile. The large colon can twist on itself (become “displaced”) and cause a blockage of both feed and gas. The gas built up in the intestine +/- loss of blood supply can cause intense abdominal pain. Abdominal ultrasound, rectal examination, and pain that is non-responsive to pain medication will help your veterinarian diagnose a large colon displacement. The only treatment for displacement of a portion of the gastrointestinal tract is surgery to replace the colon in the correct position. It is unknown what causes the large colon to displace, but it is thought that intestinal motility (normal movement of the intestine that encourages feed to pass through the GI tract) plays an important role. Things that can interrupt normal GI motility include parasites and abrupt feed change (increased gas production).
7) Strangulating small intestinal lesion – The small intestine is the portion of the intestinal tract between the stomach and the cecum. When this portion of the GI tract loses blood supply it results in severe, unrelenting abdominal pain. These horses are often intensely painful, although every horse expresses pain differently. Abdominal ultrasound, rectal examination, and abdominocentesis (collection of abdominal fluid) will help your veterinarian diagnose a small intestinal problem. The only therapy for a strangulating small intestinal lesion is surgery
