An 8-year-old male red kangaroo (Macropus rufus) from a small private zoo was evaluated because of vomiting and anorexia. Clinical signs had been noticed for at least 2 weeks prior, with a reported initial frequency of vomiting 1 to 4 times/d. The severity and frequency of the vomiting had increased over the 4 days prior to initial evaluation to 6 to 10 times/d. The kangaroo's clinical signs had become refractory to treatment with flunixin meglumine and sucralfate administered by the owner at unknown doses. A complete medical history revealed that the kangaroo had a similar vomiting episode a year before, which resolved with medical management under the care of a local veterinarian. Furthermore, there was a history of intermittent vomiting over the past year with several 1- to 2-day periods of malaise and inappetence. This kangaroo lived in a large box stall that connected to a pasture shared with 1 female kangaroo. It had no other known medical history.
Initial physical examination revealed the kangaroo to be bright and alert with a thin body condition (body condition score, 3/9) and mild muscle wasting. The kangaroo weighed approximately 68 kg (150 lb) and stood hunched, appearing to guard a moderately distended abdomen. The patient was observed to vomit 3 times during visual examination. Attempts at cardiothoracic auscultation while the kangaroo was awake caused visible signs of stress, and a complete examination was delayed until the animal was sedated. Deep sedation was achieved after administration of ketamine hydrochloridea (5 mg/kg [2.3 mg/lb], IM, once) and butorphanol tartrateb (0.2 mg/kg [0.09 mg/lb], IM, once). A complete physical examination under sedation was normal except for marked abdominal distension. Blood was then collected from the lateral tail vein and submitted for hematologic evaluation and serum biochemical analysis. Hematologic evaluation demonstrated evidence of dehydration, with elevated PCV (53%; reference range, 46% to 51%)1 and elevated total protein concentration (9 g/dL; reference range, 6 to 6.8 g/dL). The results of the biochemistry profile demonstrated moderate hyponatremia (138 mEq/L; reference range, 146 to 152 mEq/L), mild hypokalemia (4.3 mEq/L; reference range, 4.6 to 5.6 mEq/L), moderately icteric plasma, mildly elevated aspartate aminotransferase activity (124 U/L; reference range, 36 to 43 U/L), and mildly elevated bilirubin concentration (4.5 mg/dL; reference range, 1 to 4 mg/dL). Blood lead concentration and Toxoplasma antibody titers were within reference limits. General anesthesia was induced and maintained with isofluranec in oxygen administered by facemask. Once the kangaroo was anesthetized, an IV catheter was placed in the left lateral saphenous vein. Given the extent of abdominal distention, large patient size, shorter examination times versus radiography or ultrasonography, and excellent cross-sectional and multiplanar detail with image reconstruction, it was determined that CT was the most suitable imaging modality. With the patient positioned in dorsal recumbency, whole body CTd scans before and after contrast media administration (iohexole, 700 mg/kg [318.2 mg/lb] IV, once) were performed. CT images were acquired in a volumetric fashion with contiguous transverse slices, and reconstructed in 1- to 4-mm transverse, sagittal and dorsal plane images, and volume-rendered maximum-intensity projection. The images were displayed in soft tissue, bone, lung, and soft tissue postcontrast windows, and viewed on a commercial picture archiving and communication system.f
Evaluation of the results of CT revealed that the abdominal cavity was distended by a very large, sacculated, gas- and fluid-distended stomach2 (Figure 1). A moderately enlarged, gas- and fluid-filled esophagus was diagnosed as generalized megaesophagus. The dilated esophagus could be traced into the midcranial abdomen, where it tapered, and coursed slightly to the right into a whirl-like structure composed of swirling strands of alternating mesenteric soft tissue– and fat-attenuating tissue (whirl sign)3 around the celiac and cranial mesenteric arteries, with the esophagus at the center (Figure 2). The prehepatic caudal vena cava and portal vein were severely narrowed, particularly through the region of the whirl. The spleen was moderately to severely enlarged,4 had increased contrast enhancement in a speckled pattern, and was abnormally located in the right dorsal abdomen (Figure 3). The small and large intestinal segments were diffusely, mildly distended (up to 1.5 cm in diameter) with gas, fluid, and feces, with normal wall contrast enhancement. Unusually, the small intestine was divided into separate portions, with 1 part located in the left craniodorsal abdomen and the remainder in the caudal and right dorsal abdomen. The tributaries and branches of the portal vein and cranial mesenteric and celiac arteries, originating at the whirl at the root of the mesentery, were subsequently distributed throughout the abdomen toward these displaced viscera. The gallbladder was moderately enlarged and fluid distended. The bile duct was also enlarged and could be traced into the whirl, where it tapered until it was no longer visible. A small amount of fluid was dispersed throughout the peritoneal cavity. The liver was confined to the right cranial abdomen. No evidence of a tumor, foreign body, or other cause of gastrointestinal obstruction was observed. A tooth root abscess of the right lower first incisor was diagnosed on the basis of severe expansion and thinning of the alveolar bone surrounding this tooth with a large amount of periapical lucency.
Sagittal plane CT reconstruction (slice thickness, 2 mm; soft tissue window) of the abdomen of an 8-year-old male red kangaroo (Macropus rufus) evaluated because of a 2-week history of progressive vomiting and anorexia. Patient is in dorsal recumbency. The sacculated stomach is severely enlarged, with gas and fluid distension. Horizontal gas-fluid interfaces (arrows) can been seen within various stomach compartments (the fluid is dependent). Cd = Caudal. Cr = Cranial. D = Dorsal. V = Ventral.
Citation: Journal of the American Veterinary Medical Association 244, 7; 10.2460/javma.244.7.844
Sagittal plane CT reconstruction (slice thickness, 2 mm; soft tissue window) of the abdomen of an 8-year-old male red kangaroo (Macropus rufus) evaluated because of a 2-week history of progressive vomiting and anorexia. Patient is in dorsal recumbency. The sacculated stomach is severely enlarged, with gas and fluid distension. Horizontal gas-fluid interfaces (arrows) can been seen within various stomach compartments (the fluid is dependent). Cd = Caudal. Cr = Cranial. D = Dorsal. V = Ventral.
Citation: Journal of the American Veterinary Medical Association 244, 7; 10.2460/javma.244.7.844
Sagittal plane CT reconstruction (slice thickness, 2 mm; soft tissue window) of the abdomen of an 8-year-old male red kangaroo (Macropus rufus) evaluated because of a 2-week history of progressive vomiting and anorexia. Patient is in dorsal recumbency. The sacculated stomach is severely enlarged, with gas and fluid distension. Horizontal gas-fluid interfaces (arrows) can been seen within various stomach compartments (the fluid is dependent). Cd = Caudal. Cr = Cranial. D = Dorsal. V = Ventral.
Citation: Journal of the American Veterinary Medical Association 244, 7; 10.2460/javma.244.7.844
Dorsal plane maximum-intensity projection CT reconstruction (slice thickness, 10 mm; soft tissue window images obtained after contrast administration) of the patient in Figure 1. The whirl sign, created by contrast-enhancing mesenteric blood vessels swirled with fat-attenuating mesentery, is evident in the cranial midabdomen (arrows), indicating mesenteric volvulus. L = Left. R = Right. See Figure 1 for remainder of key.
Citation: Journal of the American Veterinary Medical Association 244, 7; 10.2460/javma.244.7.844
Dorsal plane maximum-intensity projection CT reconstruction (slice thickness, 10 mm; soft tissue window images obtained after contrast administration) of the patient in Figure 1. The whirl sign, created by contrast-enhancing mesenteric blood vessels swirled with fat-attenuating mesentery, is evident in the cranial midabdomen (arrows), indicating mesenteric volvulus. L = Left. R = Right. See Figure 1 for remainder of key.
Citation: Journal of the American Veterinary Medical Association 244, 7; 10.2460/javma.244.7.844
Dorsal plane maximum-intensity projection CT reconstruction (slice thickness, 10 mm; soft tissue window images obtained after contrast administration) of the patient in Figure 1. The whirl sign, created by contrast-enhancing mesenteric blood vessels swirled with fat-attenuating mesentery, is evident in the cranial midabdomen (arrows), indicating mesenteric volvulus. L = Left. R = Right. See Figure 1 for remainder of key.
Citation: Journal of the American Veterinary Medical Association 244, 7; 10.2460/javma.244.7.844
Dorsal plane CT reconstruction (slice thickness, 2 mm; soft tissue window images obtained after contrast administration) of the patient in Figure 1. The spleen, which is enlarged and has increased contrast enhancement in a speckled pattern, is abnormally located in the right side of the abdomen (arrows). See Figures 1 and 2 for remainder of key.
Citation: Journal of the American Veterinary Medical Association 244, 7; 10.2460/javma.244.7.844
Dorsal plane CT reconstruction (slice thickness, 2 mm; soft tissue window images obtained after contrast administration) of the patient in Figure 1. The spleen, which is enlarged and has increased contrast enhancement in a speckled pattern, is abnormally located in the right side of the abdomen (arrows). See Figures 1 and 2 for remainder of key.
Citation: Journal of the American Veterinary Medical Association 244, 7; 10.2460/javma.244.7.844
Dorsal plane CT reconstruction (slice thickness, 2 mm; soft tissue window images obtained after contrast administration) of the patient in Figure 1. The spleen, which is enlarged and has increased contrast enhancement in a speckled pattern, is abnormally located in the right side of the abdomen (arrows). See Figures 1 and 2 for remainder of key.
Citation: Journal of the American Veterinary Medical Association 244, 7; 10.2460/javma.244.7.844
From these CT findings, the kangaroo was suspected to have an anticlockwise mesenteric volvulus, a GDV ≥ 180° with associated splenomegaly and 45° to 90° splenic displacement, and secondary megaesophagus. An underlying cause for these pathological changes was not detected. Even though contrast enhancement of the abdominal viscera indicated adequate arterial blood supply, venous obstruction was evident. Biliary obstruction was also considered as a differential diagnosis because of the presence of icteric plasma and elevated serum bilirubin concentration. At the time of the CT scan, not all imaging findings had been thoroughly evaluated. Therefore, the kangaroo was recovered from anesthesia pending a complete review of all diagnostic tests. On the basis of the imaging results, combined with hematologic and clinical findings, surgical exploration of the abdomen was elected.
The kangaroo was again anesthetized approximately 4 hours later with midazolamg (0.2 mg/kg, IV, once) and dexmedetomidineh (0.1 mg/kg [0.045 mg/lb], IV, once), an endotracheal tube was placed, and inhalation anesthesia was maintained with sevofluranei in oxygen. The kangaroo was positioned in dorsal recumbency, and the abdomen was clipped of hair and prepared for surgery by means of standard aseptic technique. A routine ventral midline incision was made, and upon entry of the abdomen, the stomach was confirmed to be severely gas distended with omentum covering the ventral portion, similar to what is typically found in dogs affected with GDV. The proximal loops of small intestine were discolored (ie, dusky purple), appeared to be in an abnormal location, and at that time, were markedly distended (Figure 4). The spleen was not immediately identified upon entering the abdomen because it was dorsal to the distended stomach and small intestine. Once located, the spleen was an abnormal blue-gray color and displaced to the right dorsal abdomen. A small volume of serosanguinous fluid was present in the abdomen. The root of the mesentery was palpated and found to be thick and firm. The bowel was examined, and no perforations, foreign bodies, or masses were detected. The gallbladder was observed and found to be full and patent, although expressed with some difficulty. Neither a 1- or 0.75-cm-diameter orogastric tube could be passed into the stomach because of firm resistance at the cardia. The spleen was gently passed dorsally to the distended small bowel loops from right to left into its normal position. This movement was achieved with some resistance and tension, and it was observed that the remainder of the bowel began to change to a similar purple color as the more proximal small bowel loops. A 16-gauge catheter was placed into the stomach to allow gas decompression. Two liters of warm sterile saline (0.9% NaCl) solution was then poured into the abdomen, and the abdominal contents were allowed to float freely to aid in manipulation. Initial attempts to rotate the viscera counterclockwise only added tension to the attachments and exacerbated the dark discoloration of the bowel. Therefore, the intestines, spleen, and stomach were subsequently rotated (from the ventral aspect) in a clockwise direction. The viscera moved without tension and swiftly transitioned to a more normal coloration. The gastrointestinal tract was assessed as viable, and therefore, resection was not indicated. The root of the mesentery was palpated again and found to be relaxed with no suggestion of twisting within the tissue as observed previously. Biopsy samples were obtained from the spleen and liver to help identify any underlying disease that could have contributed to the clinical signs. A gastropexy was performed by scarification along a taenia band of the stomach. A 5-cm incision was made in the right ventrolateral aspect of the body wall, and scarification was performed adjacent to this site. Several simple interrupted No. 1 polypropylene sutures were placed between the sites of scarification, fixing the stomach to the body wall. A 0.75-cm orogastric tube could be passed successfully at this time. Closure of the incision and recovery from anesthesia were normal. Vitamin Ej (40 U/kg [18 U/lb], SC, once) was administered to help prevent stress or capture myopathy in this animal in light of recent confinement, travel, surgery, and hospitalization. Results of histologic evaluation of the spleen were normal; however, the liver showed evidence of biliary obstruction of undetermined chronicity.
Intraoperative photograph of the patient in Figure 1, during emergency laparotomy via a ventral midline approach. A—Notice the distended, twisted stomach with tightly wrapped omentum ventrally (large arrow) and distended, twisted loops of small intestines (small arrow). The spleen is not visible. B—Following repositioning of the viscera, the decompressed, normally located stomach (large arrow), relaxed loops of small intestines (small arrow), and the spleen are visible in the left side of the abdomen (arrowhead). See Figures 1 and 2 for remainder of key.
Citation: Journal of the American Veterinary Medical Association 244, 7; 10.2460/javma.244.7.844
Intraoperative photograph of the patient in Figure 1, during emergency laparotomy via a ventral midline approach. A—Notice the distended, twisted stomach with tightly wrapped omentum ventrally (large arrow) and distended, twisted loops of small intestines (small arrow). The spleen is not visible. B—Following repositioning of the viscera, the decompressed, normally located stomach (large arrow), relaxed loops of small intestines (small arrow), and the spleen are visible in the left side of the abdomen (arrowhead). See Figures 1 and 2 for remainder of key.
Citation: Journal of the American Veterinary Medical Association 244, 7; 10.2460/javma.244.7.844
Intraoperative photograph of the patient in Figure 1, during emergency laparotomy via a ventral midline approach. A—Notice the distended, twisted stomach with tightly wrapped omentum ventrally (large arrow) and distended, twisted loops of small intestines (small arrow). The spleen is not visible. B—Following repositioning of the viscera, the decompressed, normally located stomach (large arrow), relaxed loops of small intestines (small arrow), and the spleen are visible in the left side of the abdomen (arrowhead). See Figures 1 and 2 for remainder of key.
Citation: Journal of the American Veterinary Medical Association 244, 7; 10.2460/javma.244.7.844
The kangaroo was treated with crystalloid fluidsk (3 mL/kg/h, [1.4 mL/lb/h], IV, continuous rate infusion) supplemented with 2.5% dextrosel and potassium chloridem (15 mEq/L), buprenoprhinen (0.01 mg/kg [0.005 mg/lb], IV, q 8 h), flunixin meglumineo (0.5 mg/kg [0.23 mg/lb], IV, q 12 h), famotidinep (0.5 mg/kg, IV, q 24 h), and penicillin G procaineq (20,000 U/kg [9,000 U/lb], SC, q 24 h). The first day after surgery, the kangaroo was quiet and alert but had not shown any interest in food and had not defecated. Serosanguinous fluid was observed to be oozing from the incision site focally, but there were no signs of dehiscence. In the evening, the kangaroo was sedated with midazolamg (0.2 mg/kg, IV, once) to facilitate cleaning and bandaging of the incision site. Mirtazapiner (0.4 mg/kg [0.18 mg/lb], PO, q 24 h), an appetite stimulant frequently administered in small animals, was administered, and the kangaroo was observed eating hay shortly thereafter. The next morning, the abdominal incision continued to accumulate fresh blood at the same site, and an IV catheter placed 48 hours previously was still slowly oozing blood from the venous cut-down site. Given the increased activity of hepatic enzymes prior to surgery, and the potential for a protein-losing enteropathy following correction of the volvulus, there was concern that the kangaroo might have developed a coagulopathy. Blood was collected for a coagulation panel, which was suggestive of a mildly prolonged (Russell's viper venom) clotting time (27 seconds; canine range, 19 to 25 seconds) and normal D dimer concentration for a postoperative patient (404 ng/mL). Vitamin Ks (3 mg/kg, SC, once) was administered and the incision bandaged. Over the next 5 days in the hospital, the kangaroo steadily appeared brighter and became more active, suggesting its comfort level was improving. The incision site appeared clean and dry. The kangaroo was maintained on all previously described treatments and defecated normally starting 3 days after surgery.
Six days after surgery, the kangaroo was anesthetized to address the tooth root abscess. A buccal alveolectomy and extraction of the right mandibular first incisor were completed. A full-thickness triangular mucogingival flap was used to cover the defect. A sample for anaerobic and aerobic bacterial cultures was taken from the periapical lesion, and the tooth was submitted for histologic evaluation. Aerobic bacterial culture grew an Aeromonas sp and an Enterococcus sp, whereas the anaerobic bacterial culture grew a Bacteroides sp and a Fusobacterum-like species. Histopathologic findings on evaluation of the tooth confirmed marked periodontitis with cellular infiltrates in the periodontal ligament and a mixed population of bacteria consistent with a tooth root abscess.
The following day, it was observed that no feces had been produced since the previous morning. Gastrointestinal sounds were also decreased, and there was concern that the repeated anesthetic episodes may have caused generalized ileus. Abdominal radiographs were obtained and showed diffuse gas distension of the stomach and colon, consistent with ileus. Metoclopramidet (0.2 mg/kg, SC, q 12 h) was administered, and treatment with mirtazipine, famotidine, and flunixin meglumine was continued. By the following day, the kangaroo had an improved appetite but still had not produced feces. The kangaroo was discharged from the hospital to the care of the owners with hopes that returning to a normal environment would help to decrease stress, increase appetite and activity, and stimulate gastrointestinal motility. During the 3 weeks following discharge from the hospital, the owners reported that the kangaroo's appetite and fecal output steadily returned to normal. The kangaroo subsequently developed progressive anemia secondary to presumed gastric ulceration and was euthanized at home by the primary veterinarian 3 months after discharge. No necropsy was performed.
Discussion
Kangaroos are macropod marsupials in the order Diprotodontia.1 The red kangaroo is a large macropod with a reported5 mean male weight of 66 kg (145.2 lb). They have unique gastrointestinal anatomy, being fore-gut fermenters with a complex, composite, spiral stomach consisting of saccular and tubular regions with a small hind stomach aborally.6 Compared with cats and dogs, the esophagus opens into a more caudally located cardia, near the border of the 2 forestomach regions. Digestive system diseases, including dental disease, cecal ileus, bacterial overgrowth, parasitism, toxoplasmosis, and intestinal neoplasia, are all commonly reported.1 Mesenteric and gastrointestinal volvulus has been reported7 as the cause of death in a few captive kangaroos, diagnosed at necropsy, with disease of the gastrointestinal tract described as the leading cause of death in 1 population (31% of deaths).8 However, abdominal volvulus, defined as the acquired twisting of the gastrointestinal tract, mesentery, omentum, and other abdominal organs,9 is not common. In particular, mesenteric volvulus has been infrequently reported in the veterinary literature in any species. It has been reported rarely in cats10 and in a dugong11 but is more commonly seen in horses,12,13 cattle,14 rabbits,15 pigs,16 and dogs.17 In veterinary patients, these diseases have historically been diagnosed on the basis of results of radiography, ultrasonography, and surgical exploration, whereas contrast-enhanced multidetector CT is the current modality of choice for evaluating acute abdominal pain and gastrointestinal symptoms in people.18–23 The use of contrast-enhanced CT to evaluate abdominal disease in canine patients is increasingly accessible, with safe, fast examinations facilitating rapid and accurate diagnosis.24–26
The CT whirl sign, first described by Fisher3 as a distinctive whirl-like pattern of collapsed small-bowel loops encircling the superior mesenteric artery in a case of small intestinal volvulus in a human patient, is an important characteristic of gastrointestinal volvulus.9 It may be seen when an organ (usually intestine) rotates around its mesentery, with the appearance of a whirlpool or hurricane formed by a mass with an internal architecture of swirling strands of soft tissue created by the branching mesenteric vessels against a background of mesenteric fat.9,27,28 Various forms of volvulus in humans have since been diagnosed with the aid of the CT whirl sign, including stomach, small bowel, large bowel, and splenic volvulus.18,21–23,29–39 This sign is best appreciated when the imaging plane is perpendicular to the axis of rotation; therefore, multiplanar reconstructions (ie, in transverse, dorsal, and sagittal planes) may be necessary for identification of the whirl.9,28 Modern multiple detector array CT scanners enable acquisition of images with a notable decrease in slice thickness versus older technology, thus improving spatial resolution so that it is nearly isotropic; high-resolution multiplanar reconstructions are therefore readily produced.40 In our patient, the axis of rotation ran in a dorsoventral direction; thus, the whirl was most clearly visible on dorsal plane images (Figure 2).
The CT whirl sign is a moderately sensitive but highly specific marker for gastrointestinal volvulus, with a high positive predictive value and an OR of 254 in predicting the presence of small bowel obstruction necessitating surgery in people.18,28,30,36,41 The sign is highly suggestive of, but not pathognomonic for, gastrointestinal volvulus, as any situation that produces rotation or twisting of the mesentery and its contents may produce a whirl composed of bowel loops, mesentery, or blood vessels. Examples in human patients include adhesions, prior abdominopelvic surgery, or comorbidities such as cancer.36,42 Experience in human medicine suggests that it is a highly relevant predictor of appropriate clinical management,30 with early detection of the sign being crucial to improve prognosis and patient survival.39
In dogs, mesenteric volvulus occurs when intestines rotate around the root of the mesentery causing occlusion of the cranial mesenteric artery and its branches.43 Blood flow to the duodenum, jejunum, ileum, cecum, ascending colon, and proximal descending colon is compromised when these vessels are occluded.17 The degree of vascular obstruction and resulting ischemia can vary depending on the degree of rotation, which can be estimated from the tightness of the whirl, and therefore, severity of clinical signs and prognosis can also vary. Mesenteric volvulus is well described in humans.17 Survival rates in human patients improved with the advent of surgical intervention, and 1 retrospective study44 of 182 patients reported a survival rate of 92%, even when up to 50% of the bowel was necrotic. Survival rates in animals vary between studies and species, with horses having the highest reported postoperative survival rate (80%).12 This relatively high survival rate in horses is likely due to rapid surgical intervention as well as improvements in anesthesia and perioperative care, as reported in horses with small intestinal strangulations in general (not limited to mesenteric volvulus).45 Studies17,43,46 in dogs have found survival rates of 0%, 10%, and 42%. The generally poor prognosis and high variability in survival rates in dogs are likely due to the difficulty in achieving a quick diagnosis, considering that the clinical signs can be nonspecific and the condition of the animal can decline rapidly. Recognition of the severity of the disease and swift surgical intervention if possible are necessary to provide the best chance of survival.
Typically, clinical signs of mesenteric volvulus in dogs, including vomiting, diarrhea, hematochezia, shock, tachycardia, circulatory collapse, and death, are acute and severe.17 However, chronic mesenteric volvulus has been reported in 1 dog with intermittent clinical signs for 4 months.47 The clinical signs of the dog described in that report47 were quite similar to those of the kangaroo, although the chronic volvulus was attributed to adhesions from prior surgery, which was not a confounding factor in this kangaroo. In both cases, by the time a referral was made for a more thorough diagnostic workup, the long duration of illness allowed considerable weight loss to occur. Systemically, both animals had mild dehydration but were not in shock and had only moderate signs of abdominal discomfort. Interestingly, the dog described in the previous report47 also had elevated cholestatic and hepatocellular leakage enzymes. Biopsy samples taken at surgery in that dog indicated a chronic obstruction of hepatic venous outflow, as demonstrated histologically. The kangaroo of this report had evidence of obstruction of biliary outflow, but the extent of obstruction and chronicity remained unclear on histologic evaluation. The biliary obstruction in this kangaroo, like that in the dog described in the prior report,47 was likely secondary to mechanical obstruction and ischemia from the volvulus. Portal hypoperfusion with resulting ischemic hepatopathy as can occur in GDV48–51 might also be associated with mesenteric volvulus.47,52
Gastric volvulus involves abnormal rotation of the stomach along 1 or both of its axes. Abnormal gastric distension can predispose to volvulus, and a wandering (displaced) spleen is frequently associated with the condition.9,34,53 Gastric volvulus may be acute or chronic (or intermittent)53,54 and can be lethal. Most dogs with chronic GDV have weight loss, chronic vomiting, lethargy, and abdominal pain; the most common finding at exploratory celiotomy is a 45° to 90° rotation in a clockwise direction.54,55 In comparison, patients with acute GDV have been reported48 to commonly involve clockwise rotations ≥ 180°, often with concurrent splenic congestion. Although unfamiliar gastric anatomy particular to this species, combined with severe gas distension, made interpretation of CT images of the stomach somewhat difficult, imaging and surgical findings in this patient as well as the inability to pass an orogastric tube prior to derotation were felt to be most consistent with an acute GDV ≥ 180°.
Considering the relatively stable medical status of the kangaroo when it was first evaluated, the decision to perform an exploratory laparotomy was not immediately clear. The gastrointestinal tract, although gas distended, did not feel particularly thick or turgid on abdominal palpation. Hematologic evaluation also suggested mild dehydration and electrolyte imbalances, but given the frequency of vomiting, this was expected and likely could be quickly addressed with fluids and electrolyte replacement. However, the information obtained from CT, specifically demonstration of the whirl sign, was a critical factor in the decision-making process, resulting in surgery being performed the same day rather than pursuing medical management overnight.
This case demonstrates the possibility of mesenteric volvulus as a chronic condition and suggests that it can be successfully treated and managed in a kangaroo. In this patient, the mesenteric volvulus may have occurred secondary to pain and anorexia from a primary tooth root abscess, resulting in aerophagia, altered gastrointestinal flora, and subsequent gas distension of the gastrointestinal tract and ileus. The ensuing mesenteric volvulus was loose enough to preserve arterial supply but still caused venous obstruction. We hypothesize that GDV occurred more acutely, secondary to vomiting and ileus caused by the other gastrointestinal pathological changes. The volvuli in turn caused hepatic hypoperfusion and biliary stasis identified histologically. The sequence of events underscores the importance of proper diet, dental care, and husbandry for captive marsupials. Furthermore, this case demonstrates the successful diagnosis, treatment, and management of mesenteric volvulus in a nondomestic species. Although 1 report56 of canine splenic torsion describes a whirled or corkscrew-like soft tissue mass containing vessels as representing a rotated splenic pedicle on contrast-enhanced CT, to our knowledge, this is the first documented use of the CT whirl sign to provide critical diagnostic information used to direct case management in veterinary medicine. In cases of suspected abdominal volvulus in small animals, use of contrast-enhanced helical CT could be considered to aid diagnosis, with careful evaluation for a whirl sign as an indicator of volvulus.
ABBREVIATION
| GDV | Gastric dilatation-volvulus |
Ketaset, 100 mg/mL, Fort Dodge Animal Health, Fort Dodge, Iowa.
Torbugesic, 10 mg/mL, Fort Dodge Animal Health, Fort Dodge, Iowa.
IsoFlo, Abbott Animal Health, Abbott Park, Ill.
Aquilion LB 16-slice CT scanner, Toshiba Medical Systems, Tokyo, Japan.
Omnipaque, 350 mg of iodine/mL, GE Healthcare Inc, Princeton, NJ.
Kodak Carestream Vue Solutions, Carestream Health Inc, Rochester, NY.
Midazolam, Hospira Inc, Lake Forest, Ill.
Dexdomitor, Pfizer Animal Health, New York, NY.
SevoFlo, Abbott Animal Health, Abbott Park, Ill.
Vitamin E 300, Agri Laboratories Ltd, St Joseph, Mo.
Plasma-Lyte A, Baxter Healthcare Corp, Deerfield, Ill.
Dextrose 50%, VetOne, MWI Veterinary Supply Co, Boise, Idaho.
Potassium chloride injection, Hospira Inc, Lake Forest, Ill.
Buprenex, Reckitt Benckiser Pharmaceuticals Inc, Richmond, Va.
Banamine, Intervet/Merck Animal Health, Summit, NJ.
Famotidine injection, APP Pharmaceuticals LLC, Schaumburg, Ill.
PenOne Pro, VetOne, MWI Veterinary Supply Co, Boise, Idaho.
Mirtazapine, 15 mg, Teva Pharmaceuticals, Wales, Pa.
Vitamin K1 Phytonadione injection, Hospira Inc, Lake Forest, Ill.
Metoclopramide injection, Hospira Inc, Lake Forest, Ill.
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