Page 888 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.2 The lower gastrointestinal tr act 863

VetBooks.ir to reduce the risk of causing further tearing of the application of a temporary, indwelling rectal liner
should be performed.
defect. Abdominocentesis should be performed if a
grade 4 tear is suspected.
Prognosis
Management The prognosis for survival of horses with a grade
The management varies with the grade of tear. Horses 1 or 2 rectal tear is good. Grade 3 tears warrant a
with grade 2 tears are treated conservatively with the poor prognosis and grade 4 tears a grave prognosis.
administration of systemic broad-spectrum antimi-
crobials, NSAIDs and laxatives. The same manage- RECTAL PROLAPSE
ment is used in horses with grade 1 tears except that
the administration of antibiotics is not necessary. Definition/overview
Grade 3 and 4 tears should be referred to a hospital Rectal prolapse occurs when rectal tissue evaginates
facility for further evaluation and treatment. In order and protrudes through the anus. It is rare in horses but
to prevent faecal contamination of the abdomen, a can be associated with any condition causing tenesmus.
well-lubricated stockinet packed with cotton should
be inserted into the rectum to a level approximately Aetiology/pathophysiology
10 cm cranial to the tear. The anus is then closed using Any condition causing tenesmus may lead to rectal pro-
towel clamps or a purse-string suture and intravenous lapse in horses. It has been associated with diarrhoea,
systemic broad-spectrum antibiotics and NSAIDs are constipation, intestinal parasitism, proctatitis, colic
administered. Soaking of cotton in povidone–iodine and rectal foreign body and tumour. Type 4 prolapse
prior to insertion has been recommended. usually occurs in mares during foaling or dystocia.
Recent, clean grade 3 tears should be closed pri- The anal sphincter applies pressure on the protruded
marily using either a rectal or an abdominal approach rectal tissue and impinges on the venous return. The
through an antimesenteric small colon enterotomy. protruded tissue eventually becomes oedematous and
In both cases, a pelvic enterotomy should be per- necrotic and is prone to irritation and trauma.
formed to evacuate the contents of the large colon.
Long-duration grade 3 tears are treated medically Clinical presentation
using frequent and careful evacuation of the rectum Four degrees of rectal prolapse have been described
or, optimally, large-colon evacuation through a pel- in the equine. In type 1, only the rectal mucosa (or
vic enterotomy. part of it) protrudes through the anus (Fig. 4.178).
Grade 4 tears should be closed primarily and Type 2 prolapse occurs when there is an eversion of
either faecal diversion through a colostomy or the the entire ampula recti (Fig. 4.179). Type 3 prolapse

4.178 4.179

Fig. 4.178 Type 1 rectal prolapse. Fig. 4.179 Type 2 rectal prolapse.