for this purpose (2‐0 for large dogs, 3‐0 for small dogs and cats). The suture should be tied tight enough to prevent prolapse while allowing enough space for soft stool to pass without inciting tenesmus. To avoid excessive tightening of the suture a spacer, such as a 3‐cc syringe casing or a finger, is placed in the rectum prior to tightening and tying the purse‐string suture.
For moderate to severe, viable, complete prolapses, patients should be placed under general anesthesia to allow adequate relaxation of the rectum and perineal muscles. Epidural anesthesia can also be useful in preventing rectal spasming and providing analgesia during the reduction process as well as during the recovery. In additional to cleaning the prolapse, hyperosmotic agents can be applied to help reduce tissue edema and swelling. Various agents, including 50% dextrose solution, 70% mannitol, glycerol solution, and granulated sugar can be used for this purpose, although there is no evidence that supports the effectiveness of one agent over another. Again, gentle and consistent pressure applied to the prolapse will promote reduction. For large prolapses, this process can be time consuming but rewarding (Figure 7.2). Once reduced, a rectal exam should be performed to ensure normal anatomy prior to placement of a purse‐string suture as described above.
With the prolapse reduced, further treatment should focus on medical management of the primary inciting cause. Additionally, patients should be fed a low‐residue diet and placed on a stool softener such a lactulose or polyethylene glycol while the purse‐string suture is in place. Anti‐spasmodic medication such as aminopentamide hydrogen sulfate (Centrine®, Fort Dodge Animal Health; 0.01–0.03 mg/kg subcutaneously, intramuscularly, or orally every 8–12 hours) can be considered, but should be used cautiously as there is the potential for serious adverse effects, including ileus [8]. Topical steroids have also been recommended by some to treat anorectal inflammation [5]. Purse‐string sutures should be left in long enough to allow medical therapies to take effect in treatment of the primary disease process. Published recommendations range from five days to two weeks and are likely related to the severity of the prolapse and initial clinical signs [5, 6, 8].
Surgical Intervention
Rectal resection and anastomosis is indicated for patients presenting with prolapsed tissues that are necrotic, severely traumatized, or irreducible. Surgery should be performed as soon as the patient is deemed stable for general anesthesia. Epidural anesthesia can be useful for improving analgesia. Antibiotics that target Gram negative and anaerobic bacteria, such as a second‐generation cephalosporin, are administered perioperatively.
Figure 7.2 (a) Two‐year‐old female intact mixed‐ breed dog presented for rectal prolapse of 24 hours' duration. Note the severe congestion and edema of exposed rectal mucosa. (b) Post‐prolapse reduction. The patient was placed under general anesthesia and given an epidural. Granulated sugar was applied to edematous mucosa as a hyperosmotic agent. A purse‐string suture was placed following reduction and patient was treated for colitis and intestinal parasitism.
The perineal region is clipped widely for surgery. The patient is positioned in sternal recumbency with the pelvis raised on a padded rectal stand. If a rectal stand is not available, the pelvis can be elevated by using vacuum sandbags or other positioning devices (Figure 7.3). The area is prepped and draped. Placement of a sterile cylindrical structure, such as a syringe, blood collection tube, or test tube within the rectal opening can aid with the identification of the rectal lumen when suturing. The surgeon should identify the level at which tissues appear healthy near the anus. Stay sutures of 3‐0 monofilament suture are then placed proximal to this line of demarcation, closer to the anus. Bites should be full thickness through both the layers of the prolapsed rectum (outer everted rectum, and inner non‐everted rectum). A total of four sutures should be adequate to promote proper tissue positioning and to help maintain apposition of the rectal wall layers.
The diseased tissue is resected by incising through both layers of the prolapse distal to the stay sutures. To improve ease of tissue layer identification, resection and anastomosis should be completed in segments. Suturing is performed with 3‐0 or 4‐0 monofilament, prolonged absorbable suture using a simple interrupted pattern with 2–3 mm spacing. Full thickness bites are ideal to ensure incorporation of the submucosa (Figure 7.4). Upon completing the anastomosis, the tissues are lavaged and stay sutures are removed to allow reduction of the exposed rectum. A purse‐string suture is not needed following surgery. Depending on the patient's underlying condition, additional surgery, such as a colopexy, may be indicated.
Figure 7.3 A patient with rectal prolapse positioned for rectal resection and anastomosis. Note the padding underneath the hips.
Source: Image courtesy of S. Volk.
Figure 7.4 (a) Intraoperative image of rectal resection and anastomosis. A 1‐ml syringe has been placed within the rectal lumen to provide support to the tissue and to aid in identification of prolapse layers. Stay sutures engaging both layers of the prolapse are present at the dorsal and right lateral aspect of the prolapse. The most dorsal aspect of the prolapsed tissue has been incised to allow anastomosis of the healthy rectal tissue in a simple interrupted pattern. (b) The rectal and anal mucosal anastomosis has been completed with the syringe remaining in place. The stay suture and syringe will be removed allowing the mucosa to invert into the anus.
Source: Images courtesy of S. Volk and L. Aronson.
Continuation of antibiotics beyond surgery is not indicated. Immediate postoperative care should include appropriate analgesia, such as opioids. Additional supportive care may be required depending on the patient's clinical status. As with all rectal prolapse patients, postoperative patients should be fed a low‐residue diet and treatments geared at the primary disease process instituted. Stool softeners should be avoided unless constipation is a serious concern. Alternatively, psyllium or fiber supplement, may be administered as a bulk forming laxative to help promote normal and comfortable defecation.
Risks associated with rectal resection and anastomosis include fecal incontinence, incisional leakage or dehiscence, prolapse recurrence, and stricture formation [9]. The risk of stricture formation may be increased in cats, thus circumferential resection and anastomosis has traditionally been discouraged [6].
Colopexy can be considered for patients that experience a recurrence of rectal prolapse after having received appropriate therapy for any underlying predisposing condition. Prior to colopexy, the prolapse must be reduced. If the prolapse is irreducible or the tissue is compromised, rectal resections and anastomosis should be performed prior to the colopexy procedure.
Colopexy is most commonly performed through a ventral midline laparotomy. After completing a full abdominal explore, the descending colon is isolated and retracted cranially. While the colon is retracted, a non‐sterile assistant performs a digital rectal exam to confirm complete reduction of the prolapse. Both incisional and non‐incisional colopexy techniques are effective. For a non‐incisional colopexy, the serosa of the anti‐mesenteric surface of the colon is scarified as is the parietal peritoneum where the
