Introduction

Gastric dilatation-volvulus (GDV) is an acute condition in dogs which is characterized by dilatation and rotation of the stomach typically along its mesenteroaxial axis.¹ This is a life-threatening condition affecting primarily large-breed and deep-chested dogs.^1–5 Affected dogs are at risk of severe hemodynamic compromise, leading to hypovolemic and cardiogenic shock, gastric wall necrosis, bacterial translocation, reperfusion injury, and death.^1,6 Treatment generally includes aggressive IV fluid therapy, stabilization, and decompression followed by surgical gastric derotation and gastropexy. Depending on the surgeon’s assessment of viability, a gastrectomy for removal of devitalized tissues and splenectomy may be warranted in some cases.⁷

In both human and veterinary medicine, the terms torsion and volvulus are both commonly used interchangeably, but the term volvulus is primarily used. In human medicine, gastric volvulus is defined as rotation of the stomach of >180° from its axis, leading to a complete obstruction. The term gastric torsion is defined as a rotation of the stomach of <180° from its axis, leading to a partial obstruction.⁸ In human pediatric patients, the type of rotation does not change the clinical outcome on prognosis or treatment.⁸ In keeping with the literature, volvulus will be used primarily in the rest of this report. The rotation can be further defined by the axis on which the stomach rotates, either the mesenteroaxial axis or the organoaxial axis. The mesenteroaxial axis extends from the greater curvature to the lesser curvature of the stomach (Figures 1A, B). The organoaxial axis extends from the gastroesophageal junction to the pylorus (Figures 1A, C). A simple dilatation is defined as an engorged stomach with froth or air, but the stomach is not malpositioned.³

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The recent human literature has described gastric volvulus as rare but more commonly associated with children <5 yr of age.^8–12 The most common cause was related to congenital diaphragmatic hernias.⁸ In the rarer adult cases, the most common cause of a gastric volvulus is related with hiatal hernias.^8–10,13 There are two forms, acute and chronic gastric volvulus. The acute cases are often associated with adjacent organ deformities along with a higher risk for gastric strangulation, ischemia, and necrosis. Clinical symptoms that can be seen are acute abdominal pain, nonbilious emesis, gastric distension, and acute respiratory distress.^8–10,12 If treated, the acute cases usually have a better prognosis. In chronic cases, patients are usually asymptomatic and overall might be more difficult to diagnose.^8–10,12 Diagnosis of gastric volvulus can be challenging, the use of upper gastrointestinal (GI) contrast studies and computed tomography scan have been used.^8,14 As in veterinary medicine, surgical intervention is the recommended treatment of choice.^1–4,6,15

This case report, to the authors’ knowledge, documents the first canine case of a gastric dilatation organoaxial volvulus.

Case Report

A 9 yr old, castrated male mixed-breed dog weighing 28.4 kg was presented to the emergency department at ACCESS Specialty Animal Hospitals for acute vomiting of white foam for a 2 hr period. Physical examination revealed ptyalism and a distended abdomen that was nonpainful and soft on palpation. The dog was normothermic (38.8°C [101.8°F]), eupneic, and mildly tachycardic (100 bpm) with fair synchronous femoral pulses. He was hypertensive with a Doppler systolic blood pressure measurement of 170 mm Hg. Baseline electrolytes, venous blood gas, and packed cell volume/total solids were evaluated. The venous blood gas showed a mild acidemia (pH 7.355, reference interval 7.39–7.41) with a mild hyperlactatemia (3.2 mg/dL, reference interval <2.5 mg/dL), and mild hyponatremia (144.2 mg/dL, reference interval 145–155 mg/dL) with a normochloremia (119.9 mg/dL, reference interval 110–120 mg/dL), and increased packed cell volume/total solids (60%/8.2). Abdominal radiographs were performed which noted a markedly gas dilated stomach although the stomach position appeared to be normal (Figure 2). A cephalic intravenous catheter was placed and was administered an 1/8 of a fluid shock bolus (300 mL) IV and then started on a buffered crystalloid fluid solution^a at 100 mL/hr. He was administered maropitant citrate^b 1 mg/kg IV q 24 hr and famotidine^c 1 mg/kg IV q 24 hr. One episode of vomiting foam was noted just prior to admittance. He was walked every 2 hr to assist in increasing GI motility.

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The following morning, 8 hr after presentation, abdominal radiographs were performed which showed a persistent markedly gas distended stomach, with only slight improvement compared to the initial radiographs. A nasogastric tube was placed to decompress the stomach, due to gastric distension. He was administered hydromorphone^d 0.05 mg/kg IV and diazepam^e 0.5 mg/kg IV to assist in the placement of a nasogastric tube. A 10 French × 140 cm nasogastric feeding tube^f was placed. A right lateral thoracic radiograph was taken to confirm placement. Four hundred milliliters of a light-brown fluid and ∼1 L of air was removed. The nasogastric tube was suctioned again 4 hr later with 740 mL of light-brown fluid removed in addition to >1 L of air.

Radiographs were submitted for radiologist review and the reports are as follows: the initial radiographs showed a severely diffusely enlarged stomach, containing gas, appearing to be in normal anatomic position and moderately diffusely enlarged esophagus, containing gas. The morning radiographs showed the nasogastric feeding tube located within the lumen of the esophagus and stomach on the ventrodorsal projection. The head of the spleen was not detected in the left cranial abdomen (Figure 3). The recheck radiographs showed the stomach to be severely reduced in size but continued to appear in a normal anatomic position. Again, the head of the spleen was not detected in its normal position, this brought concern for 360° gastric dilatation with volvulus. An abdominal ultrasound was then performed by a board-certified radiologist.

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The abdominal ultrasound showed a moderately distended stomach with echogenic material. The pyloroduodenal junction was in the right cranial abdomen, although the duodenum leaving the pylorus extended leftward, coursed towards the right cranial abdomen, and then traveled caudally in a normal orientation. Malpositioning of the spleen with splenomegaly was noted; the spleen was craniodorsal to the stomach spanning the left and right cranial abdomen (Figure 4A). Within the cranioventral abdomen and caudal to the stomach there was a tortuous vessel lacking blood flow, measuring 5.2 mm, presumed to be the splenic vein (Figure 4B). There was scant anechoic effusion noted in the caudal abdomen. Surgery was recommended as a result of the malpositioning of the spleen and the pyloroduodenal junction.

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General anesthesia was induced with diazepam^a 0.5 mg/kg IV and propofol^g 6 mg/kg IV titrated to effect and maintained with isoflurane^h delivered in 100% oxygen. Heart and respiratory rates, noninvasive blood pressure, pulse oximetry, and capnometry were routinely monitored. The dog was placed in dorsal recumbency and the abdomen was prepped aseptically. A ventral midline celiotomy was performed. Abdominal exploration revealed an organoaxial gastric volvulus, rotating 180° on the gastroesophageal junction and pyloroduodenal junction (Figure 1C). The omentum was not overlying the stomach which is typically seen in mesenteroaxial gastric volvulus. The spleen was noted in the right cranial abdomen with no vascular attenuation. The body of the stomach was derotated in a clockwise direction from the right dorsal abdominal region to the left ventral abdominal region. The spleen returned to its normal anatomic position after derotation of the stomach. The remaining abdominal viscera was evaluated for any abnormalities, none were noted. The stomach and spleen were reexamined and exhibited a good blood supply. A routine incisional gastropexy was performed. The patient recovered uneventfully.

Postoperative care included ondansetronⁱ 1 mg/kg IV q 24 hr, maropitant citrate^b 1 mg/kg IV q 24 hr, famotidine^c 1 mg/kg IV q 24 hr, and a buffered crystalloid fluid solution^a (85 mL/hr) with 1.5 mg/kg/day metoclopramide^j. Analgesic treatment was transitioned from fentanyl^j constant rate infusion 3 mcg/kg/min IV to hydromorphone^d 0.05 mg/kg IV q 6 hr. Telemetry was also started to monitor for arrhythmias, with none noted overnight. The patient was bright, alert, and responsive in the morning; ate well; and IV fluids were discontinued. He was transitioned to the following oral medications: maropitant citrate^c 2 mg/kg per os (PO) q 24 hr, famotidine^c 1 mg/kg PO q 24 hr, and tramadol^k 3 mg/kg PO q 6–8 hr. An A-Fast scan was performed which showed a small stomach with no evidence of ileus or abnormalities noted. The patient was discharged that evening. He represented 14 days postoperatively for recheck with suture removal. The patient was doing well with no abnormalities noted on examination, and the sutures were removed. There was verbal communication with the owner 4 mo after surgery, and the dog was still doing well.

Discussion

GDV is an acute, life-threating condition in dogs that is characterized by dilatation and rotation of the stomach. The most common rotation seen in veterinary medicine is mesenteroaxial gastric volvulus.³ There are two studies observed in veterinary medicine related to an organoaxial gastric volvulus; the first study was a 1 yr old harbor seal who was found stranded and euthanized. A necropsy was performed, which revealed a type III hiatal hernia; the lower esophageal sphincter and most of the stomach was within the hernia sac, causing the stomach to rotate.¹⁶ The second study was based on a 1 yr old ferret with an acute onset of vomiting and who was in respiratory distress. Radiographs showed a severely gas-filled distended stomach with the pylorus located in a dorsal and cranial position. An exploratory laparotomy was performed which revealed an organoaxial axis gastric volvulus with a splenic torsion or congestion. The patient became unstable intraoperatively and was euthanized.¹⁷

In dogs with mesenteroaxial gastric volvulus, the survival rates can be high, ranging from 73 to 90%, if patients are treated with surgery in an appropriate time frame.^1,4,6,15 In patients who are treated medically, recurrence and death have been reported to have a mortality rate of 76–80%.^1,4,6,15 Radiographically, a right lateral recumbent radiograph is used to confirm the diagnosis of a typical GDV, showing a pyloric malposition with entrapment of air noting a “double bubble” sign or a “Popeye arm sign.” Physical examination abnormalities are usually consistent with a distended abdomen with a tympanic area in the cranial abdomen and unproductive retching. Hemodynamically patients can appear stable if acute, although this can change rapidly if appropriate treatment is not initiated. In recent studies, if the lactate concentration is >6 mg/dL, there is a higher risk for gastric necrosis and additional complications, which could lead to further serious injury (ischemia-reperfusion injury, multiple organ dysfunction syndrome, and/or systemic inflammatory response syndrome).^1,6,18,19 Also, if the hyperlactatemia does not improve within 24–48 hr, the prognosis is significantly decreased. ^1,6,18,19 The more prevalent breed of dogs reported have been the German shepherd dog, Great Dane, mixed-breed dogs, and standard poodle, followed by the Labrador/Golden retrievers. Age and size have not been noted to be a predisposition. In this patient, the right lateral projection was not radiographically definitive, but this patient did have a distended abdomen and was a deep-chested dog. It is unknown if the risk factors (e.g., eating dry food only, eating fast, having a nervous demeanor, and eating only one meal a day) would be similar for organoaxial gastric rotation dogs.

A gastropexy is the standard prophylactic surgical intervention, although technique may vary among surgeons. An incisional gastropexy was chosen in this case as a result of the surgeon’s experience and degree of efficiency. Other types of gastropexy include minimally invasive (endoscopic-assisted, laparoscopic-assisted gastropexy), belt-loop gastropexy, and circumcostal gastropexy.^1,3,4,15 Surgical techniques may vary depending on associated gross findings and the surgeon’s experience level. In veterinary medicine, there are only a few unsuccessful cases describing an organoaxial gastric rotation and both died before any surgical procedure was attempted.

In humans, the organoaxial gastric volvulus is rare, and it is more commonly noted to occur in young children <5 yr to infants, although it has been reported in adults. The mortality rates in both acute and chronic cases in children are low at 6.9% if treatment is performed.⁸ One child was documented to die at home because the parents elected to take him home to seek a second opinion.⁸ The chronic cases overall have a mortality rate of 2.7%.⁸ The common predisposing factors appear to be congenital diaphragmatic hernias in children and hiatal hernias in adults. In a current study with children, 23% of patients presented with life-threatening signs consisting of apnea, cyanosis, acute respiratory distress, gastric distension, and acute abdominal pain.⁸ About 71% of that population were infants <12 mo of age. Most children were treated with surgical intervention, with open gastropexies primarily performed. The common clinical symptoms noted in children was nonbilious emesis, although in adults, nonproductive retching appeared to be the primary complaint.^8,20

Confirmation of organoaxial gastric volvulus diagnosis appears to be a challenge in human medicine. One author comments on being aware of common patterns that can be consistent with gastric volvulus, including nonbilious emesis, epigastric pain, sudden onset of persistent retching, and less commonly, respiratory signs.⁸ Diagnostically, radiographs appear to be the tool used, but they may not be definitive. On right lateral radiographic projections, a mesenteroaxial volvulus will have an upright stomach with the pylorus above the gastroesophageal junction. In contrast, an organoaxial volvulus will have the pylorus facing downward with the greater curvature of the stomach higher than the lesser curvature and in front of the lower portion of the esophagus.²¹ Abdominal ultrasound, contrast upper GI studies, fluoroscopy, and computed tomography scans have been used as additional imaging and appear to play a role in the confirmation of an organoaxial gastric rotation. An abdominal ultrasound was performed in this patient after noting an abnormally positioned spleen with persistent gastric dilatation, which confirmed malpositioning of the spleen and malpositioned duodenum.

The dog in this case report presented mostly asymptomatic and continued to have mild clinical signs for 12 hr after presentation. Hyperlactatemia was not significant in this patient and could potentially be correlated with a partial obstruction. The author believes that, as a result of the organoaxial rotation of this patient’s stomach and decompression, the vascular supply was not as severely compromised. Anatomically, it is thought that the short gastric vessels are stretched with an organoaxial gastric volvulus versus being twisted with mesenteroaxial gastric volvulus, causing an obstruction of the blood supply to that region of the stomach, leading to gastric necrosis. Secondarily, with a severely dilatated stomach, the caudal vena cava and/or the portal vein are compressed, causing a decrease in preload; however, current studies in dogs are not present to confirm primary vascular compromise. Surgical abdominal exploration may be warranted if a patient presents with acute vomiting with persistent gastric dilatation and diagnostics are not consistent with a mesenteroaxial gastric volvulus.

Conclusion

GDV is a condition that is seen in both veterinary and human medicine. In veterinary medicine, it is more common to see an emergent presentation, resulting from a mesenteroaxial gastric rotation showing the classic radiographic and clinical signs. As in human medicine, an organoaxial gastric rotation can be possible, although it is rare. Veterinarians should be familiar with this rotation as the diagnosis can be more challenging and could be missed if radiographic diagnosis alone is depended on. Surgical intervention can yield a good outcome as in cases of mesenteroaxial rotation. Radiographically, the positioning of the stomach may appear normal, but if there is concern with malpositioning of surrounding structures (i.e., spleen), further imaging and exploratory surgery should be considered.