Small Animal Surgical Emergencies. Группа авторов

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 colon is to be sutured. The colon is then sutured to the left ventrolateral abdominal wall approximately 2.5 cm lateral to the linea alba. A single row of five to six simple interrupted sutures is placed through the peritoneum and then through the anti‐mesenteric surface of the colon. Attempts should be made to engage the submucosa of the colon without entering the lumen with the suture as this may lead to contamination of the colopexy site. For the incisional technique, the seromuscular layer of the colon is incised along the anti‐mesenteric surface and a corresponding incision is made at the proposed colopexy site in the parietal peritoneum. The edges of the two tissues are sutured in a simple interrupted pattern in two rows. Use of both monofilament absorbable and non‐absorbable suture have been described and suture should be sized appropriately for the patient. No difference if efficacy or complications has been reported with either suture type or colopexy technique [10, 11].

Laparoscopic and laparoscopic‐assisted colopexy has been described in dogs and a cat, respectively [12, 13]. For the laparoscopic procedure, a standard three‐cannula technique was used. The peritoneum and serosa were gently abraded using a gauze sponge introduced through a portal and the colopexy was completed by intracorporeal placement of interrupted sutures. Laparoscopic‐assisted colopexy allowed creation of a pexy through a small incision into the left inguinal region of the patient. This procedure is similar to colopexy performed through a limited paramedian approach but allows for intra‐abdominal visualization of the colon prior to incision into the peritoneum. Complications were not reported for either of these procedures.

8 Gastric Dilatation and Volvulus

       Michael S. Tivers and Sophie Adamantos

       Paragon Veterinary Referrals, Wakefield, UK

Introduction

      Gastric dilatation and volvulus (GDV) is a relatively common acute abdominal condition in deep‐chested, large‐breed dogs [1]. A study of first‐opinion emergency clinics in the UK found a prevalence of 0.64% [2]. Small and medium‐sized breeds of dog are uncommonly affected by the condition. It is extremely rare in cats but has been reported as a spontaneous condition and is also associated with diaphragmatic rupture [3–5].

      There are several syndromes associated with gastric dilatation in dogs, including a chronic form of GDV [6], and acute gastric dilatation without volvulus. This chapter focuses on the management of dogs presenting with acute GDV.

      Dogs with GDV are commonly presented with severe cardiovascular compromise and require rapid stabilization and appropriate management for successful outcomes. Since the condition was first described, mortality has reduced from 33–68% to approximately 15% [7]. Reported survival rates for GDV in referral centers in the past 15 years are between 73.2% and 90.2% [8–15].

      The management of GDV can be divided into the following steps:

      1 Restoration of perfusion.

      2 Gastric decompression.

      3 Anesthesia for exploratory laparotomy.

      4 Gastric derotation and decompression.

      5 Resection of non‐viable tissue.

      6 Gastropexy.

      7 Postoperative care and monitoring.

Pathogenesis

      The pathogenesis of GDV is poorly understood. It is thought that gas accumulates in the stomach as a result of aerophagia and rotation of the stomach occurs.

      Risk Factors

A number of studies have examined the many risk factors associated with GDV