means stone in Greek, and the prefix gives a hint to anatomical location.)
Occasionally, parasites can cause impaction colic. In heavily infested horses
(usually young horses), a massive parasite die-off from deworming can cause a
blockage in the gut. Appropriate parasite control helps avoid this.
If you live in a dry, sandy location such as the Southwest, sand impactions can
occur. Over time, some horses with chronic exposure to sand accumulate it in the
gut. This sand settles and collects, eventually leading to signs of colic and a partial
blockage. Occasional feed supplementation with psyllium, a dense fibrous material that helps cling to sand to move it through, can help prevent sand colic. But
best of all is preventing the ingestion of sand by feeding on mats or out of feeders.
A horse’s intestinal tract is enormous; if you laid it out end to end, it would be
nearly 100 feet long. After the small intestine, feed then is pushed to the hind
gut, which is made up of the 4- to 5-foot-long cecum, the large colon, and lastly
to the small colon, before entering the rectum.
While in transit, feed has numerous twists and turns to navigate, and to make
matters more complicated, some pieces of colon aren’t securely tied down. Suspended in the abdominal cavity by connective tissue, some sections of the large
colon are relatively moveable.
Normally, this is no problem. However, sometimes a section of colon becomes
distended with gas and floats somewhere its not supposed to be and gets stuck.
This is medically called a “
displacement,” and can be a big problem.
Displaced colons can get caught on
other organs, like the spleen.
If a segment of colon sits on top
of the spleen for a period of time,
blood flow is cut off. Gas and fluid
continue to accumulate and distend the digestive tract, putting the
horse in severe pain. If blood flow is
restricted long enough, parts of the
intestine will start to die. This is a
One other cause of a twist is
something called a pudunculated
lipoma. Ranging from the size of a fist
to a basketball, these are benign fatty
tumors frequently found in older
horses. Usually, they cause no problems, but sometimes a lipoma will
grow from a stalk and hang down into
the abdominal cavity. Occasionally,
The hind gut is
made up of the
cecum, the large
colon, the small
colon and the
Large colon: 10-12 feet
long; 100-liter capacity
Cecum on right, not
shown: 4-5 feet long;