or hypoperfusion should be excluded prior to pharmacological therapy. Metoclopramide (1–2 mg/kg/day as an IV constant rate infusion) can be used in this situation as a prokinetic, once other causes of ileus have been excluded.
Acute Kidney Injury
Acute kidney injury is a common complication of critical illness in dogs and has been associated with an increased risk of death. Its importance as a prognostic factor is being investigated and may play an important role in the outcome of patients suffering from GDV.
Systemic Inflammatory Response Syndrome and Disseminated Intravascular Coagulation
SIRS and DIC are common causes of death in dogs with GDV and can be difficult to manage. Should either of these processes be suspected, symptomatic therapy should be instituted. Investigation for underlying septic peritonitis should be initiated, as this may be a trigger in some cases. There are no specific therapies for either of these syndromes, the dogs should be supported with oxygen supplementation, fluid therapy and blood products as required, and should be carefully monitored for organ dysfunction.
Outcome and Prognosis
Dogs managed appropriately for GDV have a good prognosis with the majority of dogs surviving. Published surgical survival rates for GDV are variable. In the three largest studies (306–382 dogs) in the past 10 years from referral practice, the survival rate was 83.5–90.2% [7, 11, 12]. Survival rate is similar but possibly lower in first‐opinion practice, with 79.3–81.7% of surgically treated dogs surviving to discharge [2, 12]. It is worth remembering that a proportion of dogs are euthanized prior to surgery, presumably due to cost limitations, comorbidity, or perceived poor prognosis. The proportion of dogs that die or are euthanized prior to surgery has been reported as 23.3% in academic referral practice in North America, 37.4% in first‐opinion emergency practice in the UK, and 37.5% in a mixed population of first‐opinion emergency practice and private referral practice in Australia [2, 11, 12]. Younger dogs and those ambulatory at presentation were significantly more likely to have surgical management, suggesting that these factors may be linked to the decision to perform euthanasia.
As mentioned earlier, several studies have found significantly increased mortality rates for dogs with gastric necrosis and for those treated with gastric resection and splenectomy. This is perhaps unsurprising and likely reflects the severity of disease in these individuals and the potential technical challenge of gastric resection in particular. It is worth remembering that a proportion of dogs with gastric necrosis are euthanized perioperatively due to the severity of their disease and the perceived poor prognosis.
A great deal of discussion has taken place over the association with lactate and mortality [13, 14, 28–31 50]. As the findings of these studies are somewhat contradictory at this stage, lactate should not be relied on as a sole marker for prognosis [13, 14,28–31, 50]. Other factors associated with a poor prognosis include the presence of pre‐ and postoperative cardiac arrhythmias, having a splenectomy with or without gastric resection [7], and the occurrence of acute kidney injury, DIC, or sepsis [9, 25]. Few factors have been associated with decreased mortality other than time from presentation to surgery, with increased time associated with reduced mortality [7]. If an appropriate gastropexy is performed, recurrence rate is low [51].
9 Intestinal Volvulus
Elizabeth LaFond1 and Kristina Kiefer2
1 Veterinary Specialists of Sydney, Miranda, NSW, Australia
2 VetSSMART LLC, St. Paul, MN, USA
Definition and Pathophysiology
The terms “torsion” and “volvulus” are often used interchangeably. Torsion (from L. torquere, to twist) is a twisting of a structure on its long axis with one end fixed. Mesenteric torsion is a pathological rotation of the intestinal tract around the axis of the mesenteric root, resulting in rapid occlusion of the cranial mesenteric artery [1]. By necessity, mesenteric torsion involves all the intestine supplied by the cranial mesenteric artery and its branches. Intestinal volvulus (from L. volvere, to roll or turn) refers to twisting of the intestine upon itself at any point, causing obstruction. By definition, then, intestinal volvulus necessarily occurs whenever there is mesenteric torsion; however, intestinal volvulus may occur in isolation (segmental intestinal volvulus) without the presence of true mesenteric torsion. For this reason, the most accurate term to use is “intestinal volvulus” and is the term that is used preferentially in this chapter when further specificity is not warranted.
The cranial mesenteric artery branches to form the jejunal, ileocolic, right colic, middle colic, and pancreaticoduodenal arteries (Figure 9.1). Occlusion of the cranial mesenteric artery impairs blood flow to the majority of the intestinal tract, leading to ischemic necrosis, gastrointestinal toxin release, and shock [1]. Both mesenteric torsion and intestinal volvulus can result in mechanical obstruction of the intestine. With complete torsion of the mesenteric root, there is complete occlusion of mesenteric blood flow (Figure 9.2). The occlusion of blood flow leads initially to venous and lymphatic obstruction and subsequent bowel wall edema with vascular engorgement, and results in mucosal sloughing and hemorrhage into the intestinal lumen. With unchecked progression of these changes, the disease process rapidly leads to patient death. Patients that survive probably suffer from incomplete mesenteric torsion, in which some blood supply is maintained, or suffer from volvulus of only a portion of the intestinal tract.
Presentation
Intestinal volvulus is a rare condition in small animal veterinary medicine, which limits available information to that which can be extrapolated from case reports and retrospective studies [13–21]. The condition is found primarily in dogs, although a few case reports affecting cats have been published [4, 13, 17]. In dogs, the condition is more commonly found in large breeds, with a higher incidence reported in German Shepherds [12] and English Pointers [9] and rare reports in small breeds [14, 16].
The history associated with presentation is typically considered to be acute to peracute and is often non‐specific (Figure 9.3). Clinical signs include weakness, restlessness, lethargy, recumbency, hematachezia, emesis, hematemesis, diarrhea, abdominal pain, abdominal distension, and/or shock [3, 9, 15].
In most patients, physical examination reveals some degree of hypovolemic, septic, or toxic shock, depending on the duration of clinical signs [15]. Pale mucous membranes, tachycardia, prolonged capillary refill times, and weak peripheral pulses are common findings [12]. Abdominal pain and distension are typical, although not pathognomonic [18, 20].
Differential diagnoses that may present in a manner similar to intestinal volvulus include gastric dilatation and volvulus, intussusception, hemorrhagic gastroenteritis, viral gastroenteritis, intestinal foreign body obstruction, and trauma. While cause and effect is impossible to establish definitively owing to the paucity of reports in the literature, cases of intestinal volvulus have been reported to occur concurrent with other gastrointestinal diseases such as foreign body ingestion, parvovirus, gastric dilatation and volvulus, pancreatic insufficiency, lymphocytic–plasmacytic enteritis, ileocolic neoplasia, previous abdominal surgeries, congenital malformations, and trauma [6, 9, 10, 12, 16, 22]. While a relationship among these conditions is only speculative, identification of intestinal volvulus should prompt thorough evaluation for an underlying cause. One study demonstrates an association between intestinal volvulus
