Surgical procedure
Each dog was slowly administered dexmedetomidine (1 µg/kg) and methadone (0.2 mg/kg) intravenously. Anesthesia was induced intravenously with propofol (initial bolus of 2 mg/kg over 60 seconds followed by incremental bolus doses of 0.5 mg/kg) and maintained using isoflurane in oxygen. A urinary catheter was placed and the metacarpal artery was catheterized. The intraoperative blood pressure was monitored using both invasive and noninvasive techniques. Cefazolin (22 mg/kg) was administered intraoperatively at induction and every 90 minutes thereafter. A loading dose of meloxicam (0.2 mg/kg) was administered intravenously following induction. Intraoperatively, the dogs received a loading dose of lidocaine (2 mg/kg) intravenously followed by lidocaine CRI (33 µg/kg/min) and fluid therapy with lactated Ringer’s solution (6-7 mL/kg/h).
Each dog was positioned in dorsal recumbency, and both the ventral abdomen and the perineal area were prepared for surgery. A ventral midline abdominal approach was used, starting from the xiphoid to the pubis, and showed a moderate amount of peritoneal effusion.
To increase the colorectal exposure, bilateral pubic and ischial osteotomies were carried out. The division between the right and left adductor muscles was incised sharply, taking care to stay exactly on the midline to minimize the risk of hemorrhage. The adductor muscles were then elevated subperiosteally from the pubis and ischium with a 0.25-inch Key periosteal elevator. Then, elevation was continued until the obturator nerves and approximately two-thirds of the obturator foramina were visible. The prepubic tendon was incised along the pubis to the level of the proposed pubic osteotomy sites, and a 2-mm pin chuck was used to drill two holes on either side of the four proposed osteotomy sites. The osteotomies of the right and left pubis and ischium were then created using a sagittal oscillating saw. The internal obturator nerves were protected with a malleable retractor while the osteotomies were performed. The internal obturator muscle was elevated subperiosteally from the right pubis and ischium, allowing for the resection of the central bony plate to the left. Upon increased colorectal exposure, an anastomotic dehiscence was evident (Figure 1A). Initially, the dehiscence was isolated by sterile gauze. Debridement and primary closure of the colon and rectal stumps were attempted, which resulted in tension upon closure. To decrease the tension on the anastomosis, a jejunal grafting technique was utilized. A 5-cm segment of healthy jejunum (Figure 1B), including the jejunal artery and vein, were isolated and mobilized from the middle of the jejunum. The graft donor site was closed using an end-to-end anastomosis with a 4-0 polydioxanone suture (PDS) in a simple, continuous appositional pattern (Figure 1C). The pedicled jejunal segment was transposed to the anastomotic site. Cranially, the rectal and jejunal stumps were sutured in place using an end-to-end anastomosis with a 4-0 PDS in a simple interrupted pattern (Figure 2A). The rectal portion was hard to scarify and anastomose using this approach. The use of a transanal technique was thus necessary. The jejunal caudal stump was closed with a 4-0 PDS using a continuous Parker-Kerr inverting suture technique. A Doyenne clamp was inserted through the anus into the abdomen by a second surgeon to pull out the caudal jejunal stump through the anus (Figure 2B). The abdomen was lavaged with 5 L sterile saline, and a Jackson Pratt drain was placed in the peritoneal cavity and was closed without complications. The dog was then positioned in sternal recumbency and the perineal surgical field was prepared using an external operator. The jejunal caudal stump was externalized using a Doyenne clamp, and the Parker-Kerr suture was removed. A transanal-rectal-jejunal end-to-end anastomosis was performed using a 4-0 PDS in a simple continuous appositional pattern. The jejunal-rectal anastomosis was then replaced through the anus (Figure 2C).
Major complications were classified as a dehiscence of one or both of the anastomotic sites and severe rectal bleeding, whereas minor complications were classified as tenesmus, leakage, diarrhea, and fecal incontinence.