Exposure of the left colon and identification of the colorectal junction. 

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... technique has been used but never widely acclaimed. Gastrointestinal anastomoses by invagination were performed to restore gastroduodenal, ileocolic or colocolic continuity [3,4]. Experimental studies stated that the technique of anastomosis by means of invagination proved to be a most effective method of joining two parts of the colon, and both histology and the elec- tronic microscope verified the exact conjunction of the different layers [5]. The aim of this paper was to study both the external and internal features as well as the microscopic configuration of the telescoping colocolic anastomosis in dogs. 70 mongrel dogs weighing 10 to 15 Kg were ob- tained from the animal house of the faculty of veterinary medicine, Suez-Canal University, Egypt, and were housed and fed a standard laboratory diet and water up to 2 pm. Animals were fasted, except for water, for 12 hours before the surgical intervention. Neither mechanical bowel preparation nor intraoperative bowel irrigation were performed. All the experiments were done in the surgical department, faculty of veterinary medicine, Suez-Canal University, Egypt. The local ethics committee for the use of laboratory animals approved all experimental procedures. Appropriate animal care and use were performed according to imple- mentation and compliance with the Animal Welfare Act. The animals were premedicated preoperatively by intramuscular administration of chlorpromazine hy- drochloride 1 mg/kg body weight 20-30 minutes prior to surgery. Induction of anesthesia was achieved by IV administration of sodium thiopental (Thiopental sodium, EPICIO, Egypt) 2.5 % solution 20-30 mg/kg [6] via a 20 gauge intravenous cannula. Anesthesia was maintained during the operation by further small doses of thiopental sodium. The skin of the abdomen was shaved, and antisep- sis was performed using povidone-iodine. A midline incision of approximately 5 cm was made below the umbilicus to the symphysis pubis. After reaching the abdominal cavity, the left colon was exposed and the colorectal junction was identified (Figure 1). Division of the sigmoid colon was done between two non-crushing intestinal clamps (Figure 2), and bowel continuity was restored using our technique. Four invaginating sutures were performed as through and through sutures starting from 10 mm from the edge of the distal segment, then from the submucosa-serosa of the proximal segment. The needle was then introduced again about a half cm apart into the serosa-submucosa of the proximal segment to the through and through of the distal segment. Another suture was applied to the opposite end of the colonic segments. By turning the position of the intestinal clamps, the posterior aspect of the colonic segments was put into view, and the same two sutures were repeated, creating the four sutures. By tying these sutures, invagination of the proximal segment into the distal one was invited (Figure 3). Between these four sutures, the rim of the distal segment was sutured to the serosa of the proximal one (Figure 4) [7]. All dogs were observed in the postoperative period and data were collected day by day. Postoperative antibiotics [Ceftriaxone, Sandoz Egypt] were given intramuscularly as 25 mg / Kg / 24 hours, and the intravenous Ringer ’ s acetate solution was administered in a dose of 40-60 ml/ kg / day [8 ] for two days; free access to plain water was then allowed. Dogs received subcutaneous injections of tramadol (2 mg/kg) just after recovery and another dose in the evening [9]. After the scheduled three- week post-operative period [7], all survived animals were reopened for a second-look laparotomy to detect the following parameters: 1- External appearance of the anastomosis 2- Internal appearance of the anastomosis 3- Histopathological study The authors advocated a descriptive scaling system for evaluating the external anastomotic configuration. On gross examination, anastomotic lines were rated as good if there were no evidence of leakage or stenosis. A fair rating was assigned if there was stenosis only but not a leak, and a rating of poor was reserved for any evidence of leakage with or without stenosis [4]. Ste- nosis or stricture was considered where the proximal segment of the anastomosis was twice larger than that of the distal segment [5]. Internal appearance of the anastomosis : was checked for: a- A mucosal ulcer was considered if there was any mucosal loss near the suture line. Animals were classified accordingly as having good mucosal creeping, fair mucosal covering or ulcer formation. b- Perianastomotic ischaemia or necrosis. Animals were classified as having or not having areas of ischaemia or necrosis at the perianastomotic lines. c- Fate of the invaginated segment. Animals were classified as having their invaginated segment disappeared or still present (Figure 5). A good rating was considered with good mucosal creeping, no ischaemia or necrosis and disappearance of the invaginated segment. A fair rating was consid- ered with fair mucosal creeping, few ischaemia or necrosis and disappearance of the invaginated segment. A poor rating was considered in ulcer formation, massive ischaemia or necrosis or persistence of the invaginated segment. We relied on the already documented system of histological grading for the healing process proposed by Saber [1]. 1- Mucosal healing: 1- no epithelialization, 2- at- tempt at epithelialization, and 3- glandular formation. 2- Inflammatory cell exudate: 1- heavy infiltration, 2- moderate infiltration, and 3- mild infiltration. 3- Fibroblastic activity: 1- mild fibroblastic infiltration, 2- moderate infiltration, and 3- heavy infiltration. 4- Neo-capillary formation: 1- mild infiltration, 2- moderate infiltration, and 3- heavy infiltration. External appearance of the anastomosis was measured after the scheduled 3-week postoperative period; the majority of animals (52 / 70) were rated good (74.2%) and a fair rating was seen in 18/70 dogs (25.8 %), while no poor rating was detected in our experiments. During the second-look laparotomy, no fecal peri- tonitis was found in the animals ’ perianstomotic areas. Internal appearance of the anastomosis : (Table 1) Gross examination of the interior aspect of the anastomotic areas revealed that there were no mucosal ulcers in 43 animals with good mucosal creeping, 15 dogs with fair mucosal covering and 12 dogs with scattered mucosal ulcers. Regarding the perianastomotic ischae- mia or necrosis, there was no ischaemia or necrosis in animals. The invaginated segments were completely disappeared under cover of the mucosal ...