Gastric dilatation-volvulus

What it is

In gastric dilatation-volvulus (GDV) the stomach fills with gas and fluid (dilatation) and rotates around its long axis (volvulus), so that neither the cardia nor the pylorus can empty it. The distended stomach compresses the caudal vena cava and the portal vein, reducing venous return and cardiac output (obstructive and hypovolaemic shock). The gastric wall, especially along the fundus and greater curvature, becomes ischaemic and may necrose and perforate. Reperfusion injury, ventricular arrhythmias, disseminated intravascular coagulation and endotoxaemia complicate the course.

Who it affects

Large and giant breeds with a deep, narrow thorax: Great Dane (highest risk), Saint Bernard, Weimaraner, Irish setter, Gordon setter, standard poodle, German shepherd, Dobermann, basset hound. Risk increases with age, with a first-degree relative that had GDV, with a nervous temperament and with eating a single large meal a day quickly.

Anatomy involved

• Stomach: seen from the caudal aspect with the dog in dorsal recumbency, it usually rotates clockwise; the pylorus moves from the right ventral abdomen cranially and to the left, dorsal to the oesophagus and gastric body, and the fundus moves ventrally.
• Spleen: attached to the greater curvature by the gastrosplenic ligament, it is dragged along; it may become congested, twist on its pedicle or infarct, and the short gastric vessels may tear.
• Caudal vena cava and portal vein: compressed by the distended stomach.
• Oesophagus: the cardia is twisted closed, so a stomach tube often cannot be passed.

Clinical signs

Acute onset of unproductive retching, restlessness, hypersalivation and progressive cranial abdominal distension with a tympanic sound on percussion. Signs of shock follow: tachycardia, weak pulses, pale mucous membranes, prolonged capillary refill time, tachypnoea and collapse. Ventricular arrhythmias are common, sometimes in the first days after surgery.

Diagnosis

• Clinical picture: a large-breed dog with retching and abdominal distension is a GDV until proven otherwise.
• Right lateral abdominal radiograph: the gas-filled pylorus displaced craniodorsally and separated from the fundus by a soft-tissue band ("double bubble" or "Popeye arm" sign). Free gas suggests perforation.
• Blood work: lactate, electrolytes, acid–base and coagulation guide treatment and prognosis; a markedly high lactate that does not fall with fluids is associated with gastric necrosis.
• Electrocardiogram: to detect ventricular arrhythmias.

Treatment

It is a surgical emergency. First, shock is treated with intravenous fluids through cephalic veins and the stomach is decompressed by orogastric intubation or percutaneous trocarisation. Then surgery, as soon as the patient is stable: the stomach is repositioned, the viability of the gastric wall and spleen is assessed, necrotic gastric wall is resected (or invaginated) and a splenectomy is done if needed, and a gastropexy (fixation of the pyloric antrum to the right abdominal wall) is made to prevent recurrence. Prophylactic gastropexy is advised in high-risk breeds, often at the time of neutering.