Small Colon Impaction - Horse

Also known as:

Colic Impaction Simple Obstruction Descending Colon Simple Obstruction Descending Colon Obstruction Descending Colon Impaction Descending Colon Mechanical Obstruction Small Colon Obstruction Small Colon Simple Obstruction Small Colon Mechanical Obstruction

See also:

Colic, Small Colon Causes

Description

Different from other types of impaction in predispositions and clinical appearance(BLiks) Impaction of the descending colon is seen in ponies, miniature horses, and adult horses with limited access to drinking water or with other causes of intestinal stasis. Most recently, the condition has been associated with salmonellosis, although a cause and effect relationship has not been proved. Pain may be severe if the obstruction is complete. In such cases, tympany of the colon occurs secondarily, and ileus results. The diagnosis is made in adult horses by palpating the obstructing mass in the ventral portion of the abdomen on rectal examination. Foreign body obstruction of the descending colon must be considered if the horse is <3 yr old; the offending material may be rubber fencing, nylon fibers from halters or lead shanks, hay net, or feed sacks. Horses with impactions may be treated medically with analgesics, IV fluids, and gentle enemas. Often, however, surgery is required to evacuate the colon due to severity of pain and gas distention.

Aetiology

Key risk factor is diarrhoea(117 in Bliks). The oedema of the colonic mucosa associated with pro-infammatory causes of diarrhoeal disease that is usually noted in the ascendng colon but may extend into the transverse and small colons. Once diarrhoeal disease is initiated, large volumes of ingesta are rapidly expelled from the ascending colon into the small colon, which has a far smaller diameter, especialyl if it is oedematous. This may result in the intial appearance of diarrhoea, followed by intermittent episodes fo colic that may be explained by impaction. Horses should be closely observed for impaction even if dirrhoea is present. Post-diarrhoeal disease is not the only form of small colon impaction. These impactions can be formed as simple collections of ingesta or in response to luminal narrowing.

Diagnosis

Other parameters that are typically elpful for assessing the severity of colic such as heart rate, were not predictive of obstruction in horses with small colon impaction(117). Refractory colic is less pronounced in this disease.

Treatment

Horses may be treated medically during the ealry stages with fluids, laxatives and analgesics. The key clinical sign that idnicates the need for surgery is abdominal distension associated with distension of the large colon.

Prognosis

The prognosis associated with impaction of the descending colon is fair unless it is complicated by severe colitis after the obstruction has been removed. The prognosis is good.(Merck)