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Gastric Dilation Volvulus - Bloat
WHAT IS IT?
Gastric bloat and the commonly associated torsion (or twisting of the stomach) is one of life's true emergencies. It is still a condition that, when it occurs, fills vets and dog owners with dread and if it is suspected you are recommended to move fast and get help as it is a condition that progresses rapidly. Gastric bloat (or dilatation volvulus) is a rapidly fatal condition arising from the abnormal accumulation of gas within the stomach (dilatation) which may lead to rotation of the stomach (volvulus). The result is closure of the oesophagus (the tube connecting mouth and stomach) and interference with the blood flow returning to the heart. Make no mistake this is a life threatening problem and is rapid in onset and effect. In some cases the bloat is just a gas-enlarged stomach but this often becomes complicated by the stomach rotating and twisting closing off the two exits (to the oesophagus and the duodenum), thus trapping the gas in the stomach. As gas continues to be produced the expanding stomach places pressure on the abdomen closing off the portal vein, which is the vessel that drains blood from the intestine, and the posterior vena cava, the vessel that returns blood from the body to the heart. The result is dramatically reduced blood flow to the heart.
HOW WILL I RECOGNISE IT?
Gastric dilatation and volvulus rapidly induces a complex series of physiological changes which are responsible for the high mortality rate associated with this condition. It is not surprising that if the major veins from the abdomen and body are failing to return blood to the heart that there will be a back-pressure preventing blood flowing to the organs in the abdomen. This includes the kidneys and liver, as well as the bowel. The blood supply supplying the head and brain will continue but the heart will be under some considerable stress due to the lack of blood returning and the inevitable pressure changes. The lack of proper function in the kidneys and liver will not sustain life for long and the spleen which is closely associated with the stomach will be likely to be trapped and swollen too. Finally the stomach wall being seriously deprived of blood and oxygen will deteriorate and, in particular, the tissue making up the stomach-wall will start to die. Quite often during surgery the twisted stomach wall will be black and necrotic if it has been in torsion for too long. Survival is greatly improved with early detection and aggressive management prior to considering surgery, but mortality rates can still be high.
So it is important to recognise the signs of bloat and these can described as follows: retching, unproductive vomiting, excess salivation, abdominal distension, fast laboured breathing and circulatory collapse. Most of these symptoms are pretty dramatic. What could bloat and torsion be confused with? Attempts to vomit could be gastritis, but with dilatation/volvulus nothing is actually vomited. Even the excessive saliva and dribbling can be simply due to abdominal pain, but combined with a rapidly distending stomach and fast laboured breathing the diagnosis is more obvious. Bloat is very painful, especially when torsion has occurred and as the circulation collapses the dog will go into shock and become unconscious. All this can literally happen within one hour thus the urgency of the situation is clear.
WHAT CAN BE DONE?
The aims of successful case management are to at first treat the shock and stabilise the patient, secondly to remove the gas from the stomach and finally to restore the stomach to its normal place and to fix it permanently in that position. This all sounds fairly straightforward but it is not. The main problem rests with releasing the accumulated gas, for too rapid reductions in the pressure in the abdomen will allow blood to flood back to the heart and the circulation, in attempting to compensate for this sudden change, will often fail and the dog dies from cardiovascular shock. Furthermore, the intestine will be full of toxins from the damaged bowel and stomach wall and so is the blood trapped in the vessels surrounding the bowel will tend to convey this toxin towards the liver and heart. Release the pressure too rapidly and these poisons will flood to the liver and overwhelm its abilities to absorb the toxin and detoxify it. The resultant overflow passes into the main blood stream and again shock and death is the risk. This is why successful treatment first requires the use of intravenous fluids and steroids, to combat the shock, and only then followed by a careful release of the accumulated gas, to avoid rapid pressure changes and circulatory collapse. All this controlled return to normal is carried out against a background of urgency and the two do not always go together comfortably especially if the animal is unconscious and close to death. Not surprisingly even with the greatest care it can go horribly wrong.
Surgery, to restore the stomach to its rightful place, is actually the last thing to be done, quite a long time after the initial treatment and once the patient has been stabilised on fluids. The cause of bloat is not well understood but it has been associated with the abnormal swallowing of air and an inability to regurgitate it. Predisposing factors which greatly increase the risk of developing bloat are: feeding large amounts of cereal based food once a day, exercise after feeding and increasing age. Associate this with large breeds of dog with deep chests and abdomens compared to their width and this encapsulates the dogs likely to be at risk.
The article was originally published in Dog World.and our thanks go to Prof Steve Dean for allowing us to use it here. We feel that it explains the condition of GDV in a most uncomplicated way.
The following is a list of possible epidemiological aspects that could influence GDV :
GDV increases with age
Purebred dogs are more likely to be affected
Giant breeds are more likely than large breeds
Narrow and/or deep chest increases GDV risk
Single meal feeding increases risk
Dry dog food containing soya bean meal might increase risk
Exercise immediately after eating increases risk
“Stressed, fearful” dogs more likely to suffer than “calm” dogs are
Inflammatory bowel disease increases risk of GDV
Abnormal esophageal function increases risk of GDV
Long hepato-gastric ligaments (these carry the left and right gastric arteries) could increase risk of GDV
Aerophagia (air swallowing) increases risk of GDV
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