Colic, Small Colon Causes
Abnormalities involving the descending (small) colon are infrequent, accounting for <5% of conditions characterized by colic in one study. The more common causes include meconium retention, impaction, and foreign body obstruction. (Merck)
Pelvic masses
A persistent mild colic may be found when intra-pelvic masses impinge upon the gastro-intestinal tract. Most commonly these are haematomas. Peri-anal lesions, such as melanomas may also produce these signs.
Neurological deficits
A complete or partial paralysis of the small colon and rectum may occur with polyneuritis equi, resulting in a lack of faecal expulsion, and consequent obstruction. A diagnosis is made via a neurological examination. Treatment is palliative only, although the condition can be managed for many years by manual emptying of the rectum.