Acute gastric dilatation-volvulus (GDV) is an overdistension of the stomach with gas, fluid, or ingesta combined with rotation of the stomach on its mesenteric axis.
Systems. The stomach alone or in conjunction with the spleen can become devitalized due to distension and rotation. Collapse of the circulatory system can lead to cardiac arrhythmias and possible death. Multiple organ systems (liver, kidneys, brain) may also suffer damage due to a hypotensive state or bacteremia. Occasionally there is transient dysfunction of the esophagus.
Genetic Implications. Some families of large and giant breed dogs are thought to be at greater risk for developing GDV, especially if there is a first-degree relative (sibling, offspring, parent) with a history of at least 1 episode of GDV.1
Breed Predilection. Great Danes, Saint Bernards, Weimaraners, Irish setters, Gordon setters and bloodhounds appear to be at greatest risk for developing GDV.1, 2 Overall incidence of GDV in large and giant purebred dogs was reported to be 15.7% and 8.7% respectively.2 The Great Dane, assuming a longevity of 8 years, has a 42% incidence. Smaller breeds and cats are occasionally affected; dachshunds appear to be at increased risk.
Age and Range. Large and giant breed dogs greater than 5 years of age have a much higher risk factor than younger dogs.1
Gender. Male dogs, whether neutered or not, are at slightly higher risk of developing GDV than females. 2
This syndrome has a multifactorial etiology. It is presumed that gastric dilatation is the result of the animal's impaired ability to empty gas, primarily swallowed air from the environment, from the stomach and eructate when excessive gas accumulates.
Personality Traits. There appears to be a direct relationship between temperament and the tendency to develop GDV. Hyperactive animals with a fearful or "unhappy" personality are more likely to develop GDV. Stress can also precipitate GDV.1, 2
Body Condition & Anatomic Factors.
- Thin or lean body condition (giant breeds)2
- High abdominal depth (large & giant breeds)3, 4
- High thoracic-depth-to-abdominal-depth ratio (large breeds)3, 4
- Degree of thoracic depth-to-width ratio (Irish setters)5
- Rapidly eating large amounts of food (especially when fed once daily)
- Eating out of a raised feed bowl
- Feeding dry foods with fat listed as one of the first 4 ingredients
- Feeding foods containing citric acid and moistening them prior to consumption
- Feeding food with bone listed as one of the first 4 ingredients6
Gastric distension causes functional and mechanical obstruction, and relief of distension through eructation or the passage of gastric contents aborally through the pylorus is impaired. It is thought that laxity of the hepatogastric and hepatoduodenal ligaments allows enough gastric mobility to predispose to clockwise rotation of the gas-filled stomach (when viewing the animal from behind).
The short gastric vessels may become twisted, thrombosed, or avulsed. The latter can cause a hemoabdomen. Gastric distension results in decreased blood flow to the stomach wall and impairment of blood flow through the caudal vena cava and portal vein. This can result in decreased cardiac output, myocardial hypoxia, hypovolemic shock, and hypotension-leading to inadequate tissue perfusion to all organs including the heart, pancreas, kidney, stomach mucosa, and small intestine.
Cardiac arrhythmias may result from myocardial necrosis secondary to ischemia, neurohumoral factors, or toxic (endotoxin) cardiac damage. Concentrations of serum cardiac troponin I and troponin T have been recently shown to be associated with severity of ECG abnormalities.7
Cardiac and hypotensive conditions can also lead to an increased rate of endotoxin release by intestinal bacteria. Enteric bacteria and toxins move across the intestinal mucosal barrier and enter the circulatory system. Concurrent portal vein occlusion decreases the ability of the reticuloendothelial system to handle toxins and absorbed (translocated) bacteria. Hypoventilation can result from impairment of diaphragmatic movement. The spleen can become congested, thrombosed, and necrotic secondary to torsion. One report describes GDV occurring in two dogs after splenic torsion.8 There is some evidence to suggest reperfusion injury is responsible for the high mortality rates associated with GDV. 9
History. Recent episodes of self-relieving mild to moderate gastric distension, anorexia, or occasional vomiting are reported. Restlessness, retching, and ptyalism may also be observed. Depending on the length of illness, dogs become depressed and recumbent, develop a tympanic abdomen, and exhibit apparent abdominal pain (Glasgow composite pain score 6-7). This pain score reflects a dog that has some degree of groaning, is slow or reluctant to move at times, will have some degree of discomfort when palpating the abdomen, is quiet and occasionally tense. However, in some instances, owners will not recognize any degree of discomfort in their dog at the time of presentation.
Physical Examination.A grossly distended, tympanic stomach; abdominal pain; splenomegaly; and evidence of circulatory shock are often observed. Hyperpnea and dyspnea may also be present. Pulse deficits may be palpated.