1 mg/kg SQ q24 h
CRI, constant rate infusion; IV, intravenous; SQ, subcutaneous.
Complications and their Management
Together with the complications commonly associated with gastrointestinal surgery (peritonitis, dehiscence, and infection), patients with intestinal volvulus are at risk for further ischemic necrosis of bowel, reperfusion injury, bacterial translocation, and short bowel syndrome [9, 20].
Ischemic Necrosis
Ischemic necrosis is very often apparent at the time of laparotomy (Figures 9.4 and 9.5). Because of the extent of the intestine involved, the surgeon may be conservative regarding intestinal resection or may opt not to resect any intestine, resulting in residual necrotic tissue or progressive necrosis. Residual necrotic bowel leads to bacterial translocation and often fatal outcomes. In rare cases, the abdomen is managed open, or a second‐look surgery within a few days of the first is planned to reassess bowel integrity [9]. Further resection of compromised bowel is the treatment of choice for ischemic necrosis. If in doubt about perfusion to the intestines, mesenteric vasculature should be palpated to assess for pulses. If pulses are absent, ischemic necrosis is of higher concern.
Reperfusion Injury
Reperfusion injury secondary to intestinal volvulus may be unavoidable. It can lead to multiple organ dysfunction syndrome, systemic inflammatory response syndrome, or acute respiratory distress syndrome [43]. These conditions carry a grave prognosis. Therapy is aimed at aggressive supportive care.
Short Bowel Syndrome
Short bowel syndrome is an intestinal malabsorptive condition that results from extensive resection of small intestine [31, 44]. The syndrome is characterized by loss of body condition, chronic diarrhea, steatorrhea, nutritional and metabolic disorders, and fluid and electrolyte abnormalities. The average length of small intestine in dogs is considered to be approximately 3.5 times their length from crown to rump [2]. The length of bowel resection that leads to short bowel syndrome is variably reported as greater than 70–85% of the small intestine [31–33].
Few cases of short bowel syndrome are reported in the veterinary literature [31, 32,44–46]. With nutritional and supportive care, patients have been reported to adapt to the loss of bowel over one to two months; however, soft stools are frequently reported and long‐term nutritional management is necessary [31, 32, 46]. Factors that may affect the severity of symptoms include the function or presence of the ileocolic valve, the health of the remaining bowel, and the length of bowel resected [44]. In a more recent study, length of bowel resected did not seem to effect long‐term outcome in dogs that lived for a sufficient amount of time for adaptation [31].
Client education is critical. Owners should be prepared that the adaptive period requires vigilance and commitment. Despite strict adherence to dietary recommendations, significant diarrhea episodes will occur. In fact, owing to the severity of clinical signs, many of the reported cases were euthanized before a sufficient amount of time for intestinal adaptation had passed.
Therapy for short bowel syndrome is aimed at maintaining fluid and electrolyte homeostasis, providing adequate nutrition through an easily digestible diet, and controlling diarrhea [32, 46]. Pharmaceutical management frequently uses antibiotic therapy to prevent bacterial overgrowth, histamine‐2 antagonists to reduce stomach acidity, and motility modifiers to increase intestinal smooth muscle tone [32, 46]. Surgical techniques to increase intestinal surface area, modify intestinal transit times, and replace the function of the ileocecal valve have been investigated. Most studies have used the dog as a model for human disease, and most techniques have not been investigated for practical use in veterinary medicine [32,47–58].
Prognosis
Prognosis is traditionally considered poor [1, 3, 6, 7, 9, 12, 15, 18, 20], although successful recoveries have been reported. One retrospective study [20] had a higher recovery rate than previously reported [4, 10, 16], with 5 of 12 dogs recovering from surgery without enterectomy. Perhaps early recognition, immediate supportive and surgical intervention and anticipation of, and preemptive treatment for, the most severe sequelae can improve the success of recovery. Breed and time to intervention are suspected to play a role in prognosis [3–10,13–15, 18, 20, 21]. It has been proposed that a partial torsion of the mesentery carries a better chance of survival than a complete torsion [9]; however, recurrence is possible, even though risk factors for recurrence are unknown (Case Report 9.1). Unfortunately, owing to the rarity of the condition, a prospective study assessing outcomes and factors influencing survival is unlikely.
10 Colonic Torsion
Chloe Wormser
Elite Veterinary Surgery, Northway Animal Emergency Clinic, Saratoga Springs, NY, USA
Introduction
Colonic torsion is a life‐threatening condition characterized by rotation of the colon around its mesenteric attachment. This results in partial to complete cessation of colonic blood flow. If untreated, necrosis of the colonic wall and septic peritonitis due to colonic perforation are potential sequelae. In cases where the torsion involves the cecum and ileocolic junction, the cranial mesenteric vessels and small intestines are often also compromised. In contrast, torsion of the descending colon may leave cranial mesenteric blood flow largely unaffected and appears to carry a more favorable prognosis than that of mesenteric torsion [1].
Pertinent Anatomy
The colon can be divided grossly into three segments: ascending, transverse, and descending. The ascending colon and transverse colon are relatively fixed in position due to their attachments to the mesoduodenum and mesocolon. The descending colon is the longest and most mobile segment of the large intestine [2].
The colon receives its blood supply from branches of the cranial mesenteric artery, except for the aborad half of the descending colon which is supplied by branches of the caudal mesenteric artery (Figure 10.1) [3]. The blood supply to the colon is distinct from that of the small intestines in that arteries enter the colonic wall via short branches known as vasa recti. Venous drainage is by way of the portal vein [2].
Signalment and Clinical Presentation
Colonic torsion has been infrequently described in dogs. The majority of patients are large breeds and young to middle aged [1]. The most common clinical signs associated with the disease include vomiting, depression, inappetence, and diarrhea, with or without tenesmus. Less commonly, dogs can present in hypovolemic shock with marked abdominal distension and/or pain [1, 4, 5, 6]. Colonic torsion has been described in dogs with previous gastric dilatation‐volvulus that underwent gastropexy. In approximately half of these cases, large intestinal entrapment and strangulation around the previous gastropexy site was found at the time of abdominal exploratory surgery
