In dogs that have gastric dilatation volvulus (GDV), also known as gastric dilation, twisted stomach, or gastric torsion, the stomach is stretched too far and rotates due to an abundance of gas. When referring to GDV or gas distension without stomach torsion (a typical change after eating), the term "bloat" is frequently used in a generic sense. Gastric dilatation is a serious illness that primarily affects large breeds of dogs with deep chests. Bloated dogs are agitated and unable to relax; they may drool saliva and vomit foamy foam. GDV is a serious illness that must be treated right away in canines, it is an emergency as bloat kills in less than an hour. Even with treatment, dogs still experience mortality rates between 10 to 60%. The mortality rate after surgery ranges from 15 to 33%.
What is bloat (GDV Syndrome)?
Bloat is an accumulation of gas in the stomach. The gas can be produced from the fermentation of food material in the stomach or from swallowing air. In normal dogs, burping quickly relieves the pressure in the stomach but in some dogs, there is a problem that prevents the normal emptying of the stomach. Gas continues to build up causing the stomach to inflate like a balloon. As the stomach swells it may flop over to one side. This can block off the exit for gases - making the problem progress more rapidly. The stomach can also twist on itself. If this occurs the condition is termed gastric dilatation and volvulus (GDV) and is a life-threatening condition. When a dog's stomach becomes distended with gas and twists on itself, the blood supply to the stomach and other organs is cut off.
Which breeds of dogs are more predisposed to bloat?
Large breed dogs, particularly the German Shepherd Dog, Irish Setter and Great Dane, are most at risk from this condition. Other breeds include Boerboel, Saint Bernard, Dobermann Pinscher and Weimeraner. Bloat most commonly affects middle-aged or older animals.
What are the clinical signs of bloat (GDV Syndrome)?
Generally, the first signs noticed in a dog affected by bloat are restlessness coupled with retching and drooling of saliva. The dog may show attempts to vomit but only a little frothy foam may be produced. The abdomen may become swollen and firm to the touch (although this isn't always obvious). Affected dogs may look at their sides or show other signs of abdominal pain. Some dogs may cough and others want to drink a lot of water. As the condition progresses the dog may have difficulty breathing and eventually will collapse and be unable to get up. If untreated, dogs that develop a twist in the stomach will die. If a dog is suspected of having bloat, it is an emergency and time is of the essence because bloat can kill in less than an hour.
How does bloat (GDV Syndrome) happen?
First, there are potential predisposing factors that lead to bloat. These include:-
Large and giant breed dogs although it can occur in small dogs and cats.
Deep-chested breeds with an increased thoracic depth:width ratio, the main predisposing characteristic possibly due to prevention of belching or burping.
Gastric distension due to significant gas accumulation resulting from aerophagia (excessive air swallowing, which goes to the stomach instead of the lungs) as well as from carbohydrate fermentation.
Eating out of raised food bowls.
Highly stressed individuals.
Older age.
Having a first-degree relative with a history of GDV.
The initial stages of dilatation involve the buildup of gas in the stomach due to aerophagia and ingesta fermentation. When the typical mechanisms of eructation (belching), vomiting, and, less significantly, pyloric outflow fail, stomach fluids and intestinal secretions also build up and the gastric content cannot escape the stomach.
Simple dilation may be the extent of the syndrome's progression, or, when viewed from below, the stomach may start to rotate clockwise or anticlockwise around its oesophageal attachment (the muscle tube via which food travels from the throat to the stomach). The most typical type of volvulus involves rotation between 90° and 270° in a clockwise orientation.
Concurrent pathophysiological changes or functional alterations brought on by GDV include the following:-
With or without torsion, stomach enlargement results in compression of the caudal vena cava, portal vein, and splanchnic veins, which lowers preload, lowers cardiac output and causes hypotension.
Significant stomach distension inhibits the diaphragm's normal excursion, increasing the respiratory rate and effort and causing hypoxemia from insufficient ventilation brought on by gastric distension and reduced diaphragmatic motility.
Large volumes of blood are sequestered in the portal circulation, which leads to the development of hypovolemic shock. Along with central venous pressure, cardiac output, stroke volume, and arterial pressure, venous return also declines.
The most frequent and harmful electrolyte abnormality is hypokalemia, which is brought on by potassium loss into the stomach lumen.
The short gastric arteries that supply the greater curvature and fundic regions of the stomach are torn and occluded, resulting in the development of gastric necrosis. These regions' gastric mucosa is especially susceptible to severe ischemia, which can cause perforation and the necrosis of sizable portions of the stomach.
About 40% of patients with GDV experience cardiac arrhythmias. cardiac arrhythmias brought on by myocardial ischemia, hypoxia, and reperfusion damage from reduced venous return in the early stages of the illness.
As gram-negative bacteria multiply in the ischemic stomach and are allowed to get through the gut wall into the blood, endotoxemia may form, further aggravating the shock syndrome.
Disseminated intravascular coagulation (DIC) can result from septicemia, haemorrhage, ischemia-reperfusion injury, severe hypertension, severe tissue hypoxia, and endotoxemia, as well as from stomach necrosis and dilutional coagulopathy after vigorous fluid resuscitation.
Raised liver and kidney enzyme concentrations are examples of enzyme alterations.
How is bloat, Gastric Dilatation Volvulus diagnosed?
The diagnosis is based on the dog's history, physical examination, detection of a distended gas-filled stomach and other signs indicating the condition. If the breed of the dog is predisposed to gastric dilation, this is also taken into account. Diagnosis may be confirmed with an X-ray as it can show whether the stomach is twisted or not. A twisted stomach is much more dangerous. If there is no twist to the stomach, a tube is passed into the dog's stomach to allow the trapped gas to escape.
The stomach contents can also be washed out through this tube which may help to improve the dog's condition. Blood samples are also taken and perhaps an Electrocardiogram (ECG), as dogs with bloat may develop abnormal heart rhythms. In severe cases, treatment may be started before all test results are obtained as early treatment may be essential to save the dog's life.
How is Gastric Dilatation Volvulus Syndrome treated?
Animals with bloat experience shock, thus this condition is treated with intravenous fluids (a drip) and other medications. A tube is inserted into the stomach to release some gas and relieve pressure on the internal organs in order to treat the bloat itself. This isn't always possible, though, because the stomach is occasionally twisted and prevents the tube from entering. It could be required to do surgery in some situations to empty the stomach. Sadly, no matter how it is treated, the disease is serious. Even after surgery, about 3 out of every 20 canines will not survive. Upon surgery, some dogs will suffer extensive organ damage.
What is a gastrostomy tube?
A gastrostomy tube is a rubber pipe placed at the time of stomach surgery. One end of the tube is attached to the inside of the stomach. The other end passes through the stomach wall and then through the body wall and is fixed to the outside of the body. This tube serves 2 purposes; any gas produced in the stomach can be safely vented through the tube without risk of stomach dilation, and the stomach becomes fixed to the body wall at the point where the tube leaves. This prevents stomach twisting from ever happening again. The gastrostomy tube may be left in place for a week and can be removed without further surgery when the dog is making good progress. After removal, a small hole will be left in the body wall but this soon heals.
Does Bloat Recur?
Dogs that have experienced stomach dilatation are susceptible to experiencing it once more. In fact, if prophylactic measures are not implemented, 8 out of 10 dogs who have bloat will experience it again. Surgically the stomach can be joined loosely to the interior of the body wall (known as gastropexy). As a result, there is a much lower chance of a repeat episode because the stomach is kept from twisting and moving. In actuality, only 3 out of 100 bloated dogs will experience another episode after this treatment.
How is the risk of Gastric Dilatation Volvulus (GDV) reduced?
Unfortunately, many of the risk factors for bloat cannot be changed. But there are some sensible steps that can be taken to lessen the risk. In vulnerable breeds and people, feeding multiple little meals each day (instead of one large one) can help lower the risk. It can be beneficial to separate dogs when eating so that there is no competition for food and eating is not hurried because swallowing of air is enhanced when dogs eat quickly. There are barrier bowls on the market intended to slow a dog's feeding. Avoid strenuous activity and binge drinking for an hour before and after eating.
Contrary to popular perception, feeding a dog from a raised food stand actually raises the risk of bloat. Instead, avoid doing this and feed your dog as usual from the ground.
Another thing that may contribute to bloat formation is stress. A disruption in routine, such as boarding kennels, dog shows, or the addition of a new dog to the household, can kick off an episode in extremely sensitive dogs, thus owners of such dogs should be extra cautious during these times.
References
Raghavan M, Glickman W R & Glickman L T (2006) The Effect of Ingredients in Dry Dog Foods on the Risk of Gastric Dilatation-Volvulus in Dogs. JAAHA 42 (1), 28-36.
Glickman L T et al (2000) Incidence of and breed-related risk factors for gastric dilatation-volvulus in dogs. JAVMA 216 (1), 40-45.
Aronson, Lillian R.; Brockman, Daniel J.; Brown, Dorothy Cimino (2000). "Gastrointestinal Emergencies". The Veterinary Clinics of North America. 30 (1): 558–569. doi:10.1016/s0195-5616(00)50039-4.
Beck J, Staatz A, Pelsue D, Kudnig S, MacPhail C, Seim H, Monnet E (2006). "Risk factors associated with short-term outcome and development of perioperative complications in dogs undergoing surgery because of gastric dilatation-volvulus: 166 cases (1992-2003)". J. Am. Vet. Med. Assoc. 229 (12): 1934–9. doi:10.2460/javma.229.12.1934.
Glickman L, Glickman N, Schellenberg D, Raghavan M, Lee T (2000). "Non-dietary risk factors for gastric dilatation-volvulus in large and giant breed dogs". J. Am. Vet. Med. Assoc. 217 (10): 1492–9. doi:10.2460/javma.2000.217.1492.