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==== Obstruction ====
==== Obstruction ====
Intestinal obstruction can be the sequel to either mechanical or functional causes. Mechanical obstruction occurs due to physical blockage of the intestinal lumen whereas functional obstruction results from a decrease or inhibition of intestinal motility due to loss of smooth muscle contraction. (Brown et. al, 2007).
Intestinal obstruction can be the sequel to either mechanical or functional causes. Mechanical obstruction occurs due to physical blockage of the intestinal lumen whereas functional obstruction results from a decrease or inhibition of intestinal motility due to loss of smooth muscle contraction. (Brown et. al, 2007).
===== Physical =====
===== Mechanical =====
Mechanical obstruction of the intestine, either acute or chronic, can occur in all species of animals. Acute obstruction usually involves the upper or middle small intestine whereas chronic obstruction typically occurs in the distal small intestine or large intestine. Causes of obstruction can be divided into three main categories: intraluminal, intramural, or extrinsic. Intraluminal causes include food impaction and foreign bodies, intramural causes include neoplasia and extrinsic causes include adhesions, neoplasia and prostate enlargement. The following figure illustrates the pathogenesis occurring in intestinal obstruction [Figure].
====== Foreign Bodies ======
====== Foreign Bodies ======
*Foreign bodies of all types can be found in the intestines. While some may pass through posing no problems, others can cause acute obstruction and lead to pressure necrosis and eventually perforation. Foreign bodies can also be chronic, remaining for long periods of time without causing disturbance.
*Foreign bodies of all types can be found in the intestines. While some may pass through posing no problems, others can cause acute obstruction and lead to pressure necrosis and eventually perforation. Foreign bodies can also be chronic, remaining for long periods of time without causing disturbance.
*Enteroliths, stones consisting of magnesium ammonium phosphate around a central nidus (often a metallic foreign body) occur mostly in horses. Typically, they lodge at the pelvic flexure or the transverse colon and affect horses greater than 4 years of age.
====== Impaction ======
====== Impaction ======
Impacted ingesta/faeces within the intestines can occur in all species though it is especially common in horses. Predisposing factors in horses include poor dentition, a high roughage diet, and general debility.
*Impaction commonly occurs in the equine colon although impaction due to fibrous ingesta can occur in the ileum.
*Impaction can be common, especially in horses following antihelminthic administration.
====== Extrinsic ======
====== Extrinsic ======
Neoplasia, Adhesions, Prostate enlargement
Neoplasia, Adhesions, Prostate enlargement