Rectal prolapse may be predisposed by conditions which increase intrapelvic pressure or abdominal straining such as persistent riding behavior, coughing, coccidiosis and chronic diarrhoea. Vaginal prolapse in females and urinary tract obstruction in males may also predispose to rectal prolapse. Any partial, intermittent prolapse may lead to rectal mucosal injury and irritation, more straining and eventually complete prolapse.
Once prolapsed, the blood supply becomes compromised and affected tissue will swell, become congested, oedematous and eventually necrotic. Without intervention there is a risk of peritonitis and death.
Occasional cases may be seen in the live export process.
A large cylindrical mass of dark congested friable tissue protruding from the anus will probably be prolapsed rectum but should be differentiated from anal warts which are hard, pale and nodular, and vaginal prolapse, which protrudes from the vulva.
Treatment should not be delayed as swelling and necrosis will rapidly make manual or surgical correction more difficult.
Small, recent rectal prolapses with little swelling may be reduced manually under caudal epidural anaesthesia to reduce straining, and using soapy water or lubricant to help with replacement. Insert a loose, anal purse-string suture to prevent recurrence while leaving a two finger opening to allow passage of faeces. Remove after one week by which time swelling will have disappeared if the underlying condition has been corrected.
If the prolapse is irreducible because of necrosis, size or trauma, then submucosal resection or amputation should be attempted. Submucosal resection is preferred to amputation because there is less risk of rectal stricture.
A field amputation method involving poly- or PVC pipe (about 2.5cm in diameter) has been used effectively on export vessels (Manefield GW, Control and Therapy article number 4770, 2007). The pipe is inserted into the prolapsed rectum and rubber bands or suture material applied over the prolapse to form a tight ligature against the pipe, with the ligature placed close to the anal spincter. The animal will defaecate through the pipe during healing. At the site of the ligature healthy proximal tissue will anastamose and the tissue distal to the ligature will necrose and fall away with the pipe after a week or so. A set of 3 different diameter pieces of pipe can be carried on board in case prolapses occur.
Alternative approaches to amputation have also been described. One approach involves placing a series of U-sutures around the base of the prolapse. A 23cm Gerlach needle carrying two 30cm lengths of heavy duty absorbable suture (sutures 1 and 2) is inserted into the lumen of the prolapse and the prolapsed tissue penetrated from the inside to the outside. The Gerlach needle is then used to carry the inner end of suture 2 and a new suture 3 from the lumen to the outside about 3 cm from the first penetration. Suturing continues in this manner for the circumference of the prolapse until there is a series of U-sutures around the prolapse. Each suture is tightened and tied, then the prolapse excised about 2 cm distal to the sutures. No haemorrhage occurs due to the ligation of the tissues. Spontaneous retraction of the stump occurs.
Simultaneously treat any underlying cause such as pneumonia, urolithiasis or diarrhoea. Prompt euthanasia is recommended if the prolapse cannot be corrected or amputated.
Prevention and treatment of predisposing underlying diseases and conditions such as pneumonia, riding behaviour or urinary obstruction are required to prevent rectal prolapse. If these diseases and conditions occur, then there must be awareness of the possibility of rectal prolapse occurring and systems for early detection and intervention should be implemented.