Small Intestine Impaction - Horse

Description

Small Instestinal impaction causes total or partial obstruction of the instestinal lumen resulting in colic. The obstruction is most often associated with ascarid impaction, ascarid infection in young horses, or ileal impaction due to ingestion of bermuda grass in the USA or tapeworm infection in the UK.

Impaction may also result due to postoperative ileus; the risk can be minimised by good surgical technique, appropriate postoperative care and the adminstration of prokinectic drugs.

Signalment

Foals and yearlings are particularly susceptible to infection with ascarids, impaction usually occurs following the adminstration of an anthelmintic with a high efficacy.

Ileal impaction is more common in younger animals which are at greater risk of infection with tapeworms such as Anoplocephala perfoliata.

Diagnosis

Clinical Signs

Clinical sigs are of simple small intestine obstruction. There will be additional signs of parasite infestation in cases associated with ascarid and tapeworm infection.

The severity and speed on onset of clinical signs is determined by the level of the obstruction. Proximal obstructions will progress more rapidly than distal ones.

Passage of a stomach tube will produce nasogastric reflux depending on the site of obstruction and its duration; for a proximal obstruction fluid will build up in the stomach after approximately 3-6 hours, and for a distal obstruction, after 12 hours. Gut sounds will decrease as the small intestine becomes distended and atonic.

On rectal examination the small intestine is palpable as distended loops; in the early stages of ileal impaction a tubular structure may be felt in the mid abdomen.

Signs of colic

See Colic Diagnosis in Horses

Treatment

Surgical management is recommended for small instenstine impaction. A ventral midline laparotomy is carried out to gain access to the small intestine and assess

See Medical Treatment of Colic in Horses

Refernces

• Mair, T.S, Divers, T.J, Ducharme, N.G (2002) Manual of Equine Gastroenterology, WB Saunders.
• Merck & Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial