Rectal prolapse occurs in a wide range of species and may be caused by enteritis, intestinal parasites, rectal disorders and other underlying conditions. Diagnosis can be made based on the clinical signs (ie, a cylindrical mucosal mass protruding from the anus). Treatment includes lavage of the protruding tissue, reduction, and placement of a temporary purse-string suture. Local anesthesia may help reduce straining and aid in prolapse reduction, especially in large animals.
In rectal prolapse, one or more layers of the rectum protrude through the anus due to persistent tenesmus associated with intestinal, anorectal, or urogenital disease. Prolapse may be classified as incomplete, in which only the rectal mucosa is everted, or complete, in which all rectal layers are protruded.
Etiology of Rectal Prolapse in Animals
Rectal prolapse is common in young animals in association with severe diarrhea and tenesmus. Causal factors include:
severe enteritis
endoparasitism
disorders of the rectum (eg, foreign bodies, lacerations, diverticula, or sacculation)
neoplasia of the rectum or distal colon
urolithiasis
urethral obstruction
cystitis
dystocia
colitis
prostatic disease
Perineal hernia or other interruption of normal innervation of the external anal sphincter may also lead to rectal prolapse.
Animals of any age, breed, or sex may be affected. Rectal prolapse is probably the most common GI problem in pigs due to diarrhea or weakness of the rectal support tissue within the pelvis. In cattle, it may be associated with coccidiosis, rabies, or vaginal or uterine prolapse; occasionally, excessive “riding” and associated traumatic injury may be causative in young bulls. It is common in sheep with short tail docking and especially in feedlot lambs, in which high-concentrate rations may be causative. The use of estrogens as growth promotants, or accidental exposure to estrogenic fungal toxins, may also predispose large animals to rectal prolapse.
Clinical Findings and Diagnosis of Rectal Prolapse in Animals
Diagnosis is based on the primary clinical sign, a cylindrical tissue mass protruding from the anus
The primary clinical sign, an elongated, cylindrical mass protruding through the anal orifice, is usually diagnostic. The mass must be differentiated from prolapsed ileocolic intussusception by passing a probe, blunt instrument, or finger between the prolapsed mass and the inner rectal wall. In rectal prolapse, the instrument cannot be inserted because of the presence of a fornix. Other common signs include ulceration, inflammation, and congestion of the rectal mucosa. Shortly after the onset of a prolapse there is a short, nonulcerated, inflamed segment of rectal tissue; later, the mucosal surface darkens, hardens, and may become necrotic.
Courtesy of Dr. Sameeh M. Abutarbush.
Treatment of Rectal Prolapse in Animals
Treatment includes lavage of the protruding tissue, reduction, and placement of a temporary purse-string suture
In all animals, identifying and eliminating the cause of prolapse is of primary importance.
In small animals, treatment includes prompt replacement of viable prolapsed tissue to its proper anatomic location, or amputation if the segment is necrotic. Small or incomplete prolapses can be manually reduced under anesthesia by using a finger or bougie. Warm saline lavage and lubrication with a water-soluble gel should be applied to the prolapsed tissue before reduction. Alternatively, hypertonic sugar solution (50% dextrose or 70% mannitol) applied topically may be used to relieve edematous mucosa. The placement of a loose, anal purse-string suture for 5–7 days is indicated. Straining may be prevented by applying a topical anesthetic (1% dibucaine ointment) or by administering a narcotic epidural injection before or after reduction or correction. Postoperatively, a moistened diet and a fecal softener (eg, dioctyl sodium sulfosuccinate) are recommended. Diarrhea after surgery may require treatment.
When questionable viability of tissue prohibits manual reduction, rectal resection and anastomosis are required. When rectal tissue is viable but not amenable to manual reduction, celiotomy followed by colopexy is indicated to prevent recurrence. As in medical management, epidural anesthesia may be used to reduce straining.
In large animals, caudal epidural anesthesia is suggested to reduce straining, facilitate repositioning of the prolapse, and permit surgical manipulations. Reduction and retention with a purse-string suture is recommended. The suture should be loose enough to leave a one-finger opening into the rectum in pigs and sheep, and slightly larger in cattle and horses. Rectal prolapse in mares, if neglected, can lead to prolapse of the small colon. The blood supply to the small colon is easily disrupted. Replacement of a rectal prolapse with prolapse of the small colon followed by purse-string suture of the anus has a poor prognosis.
More aggressive treatment of the prolapse is dictated by the condition of the rectum. In general, the prolapse may be salvaged by conservative measures, unless obvious deep necrosis or trauma to the tissue exists, or the everted tissue is firm, indurated, and cannot be reduced. Under these circumstances, submucosal resection or amputation should be considered. Amputation of the rectum should be reserved for severe cases. Complete amputation has a higher incidence of rectal stricture formation, especially in swine. A prolapse ring, syringe case, or plastic tubing may be used as an alternative to surgical amputation in pigs and sheep. Postoperatively, the animal should receive antibiotics. Fecal softeners may be used in horses. Usually, it is not economically feasible to repair rectal prolapses in lambs ready for market.
Key Points
Rectal prolapse is typically the consequence of other diseases that result in significant tenesmus or is caused by nerve injury that results in anal sphincter incompetence.
Diagnosis of rectal prolapse is based on physical examination. Further evaluation may be needed to determine the cause.
Treatment requires either manual reduction of the prolapsed tissue or surgical resection and anastamosis.
