Bloat (Gastric Dilatation and Volvulus)

Introduction | Causes & Prevention | Symptoms & Signs | Diagnosis & Test | Treatment Options

Bloat (Gastric Dilatation and Volvulus)

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Introduction

Gastric dilatation and volvulus (GDV), commonly called "bloat" or "torsion," is an extremely serious medical condition where a dog's stomach becomes filled with gas that cannot escape. The stomach also can rotate around its short axis, often carrying the spleen along for the dangerous ride. By itself, "bloat" technically refers only to the gaseous distension of the stomach, without the flipping-over, or "torsion," part of the condition. However, most owners think of "bloat" as referring to the syndrome of both gastric distension and rotation, and we will call both conditions "bloat" in these articles. Think of it as if the stomach is a balloon that keeps filling with gas, but the "escape route" is twisted or tied off. Eventually, the balloon will rupture. Similarly, the stomachs of dogs suffering from gastric dilatation and volvulus can rupture, spilling intestinal contents into the abdominal cavity. Bloat is life-threatening and requires immediate and aggressive medical attention if the dog is to survive. Without emergency treatment, bloat can be fatal within a matter of hours of the appearance of clinical signs.

Causes & Prevention

Causes of Canine Bloat
The precise triggers of GDV are not well-understood. However, the physiological processes are. When the stomach rotates on its axis (think of this as the connection between the stomach and the esophagus on one end, and the stomach and small intestine on the other), gas in the stomach becomes trapped. It can no longer escape back up the esophagus through burping (called eructation), nor can it escape down through the gastrointestinal tract, because both the entrance to and exit from the stomach are twisted and thus obstructed. The increasingly distended stomach compresses the diaphragm and the major abdominal blood veins, shutting down digestion and reducing venous blood return to the heart. This, in turn, decreases the amount of blood that the heart can pump out into circulation, which causes an inadequate supply of oxygen to be distributed throughout the dog's body. Vital organs become unable to function, the gastrointestinal tissues start to ulcerate and die (necrose), and within a very short period of time the dog goes into hypovolemic (low circulating blood volume) and hypotensive (low blood pressure) shock. The dog is now fighting for its life. Why this process happens is still a medical mystery. A number of different contributing factors have been suggested, but none have been proven.

Preventing Bloat in Dogs
Once a dog has bloated, it is more likely to bloat again. Surgical options are available to reduce the chance of bloating even before it has happened, as well as to prevent recurrence. The general name for this surgical procedure is gastropexy. When done preventatively, it is called prophylactic gastropexy. Another general term for the procedure is "stomach tacking." There are several different ways that veterinarians can surgically attach, or "tack," the stomach to the abdominal wall in an attempt to prevent it from torsing in the future. While these procedures are usually very helpful, they are not fail-proof. Other preventative measures involve dietary and exercise management and moderation. Many breeders and veterinarians recommend feeding at-risk dogs from elevated feeders, while some advise against this practice. Other suggestions are to restrict activity for an hour or so both before and after meals, and to feed at least twice daily. Dogs that eat a single, large meal of dry kibble and then drink large amounts of water and/or become active seem predisposed to bloat. Dogs with a history of bloat should be taken out of any breeding program.

Special Notes
Bloat is a life-threatening condition. Without immediate medical care, the chance of survival is extremely low. If you own a large deep-chested dog – or indeed any dog -- please make sure that you have a good relationship with your local veterinarian and that you are familiar with the signs of this condition, so that if it happens to one of your dogs, you are prepared to deal with it immediately.

Symptoms & Signs

Introduction
Clinical signs of bloat are not always easy to distinguish from other kinds of gastrointestinal distress. A dog that stands uncomfortably and seem to be in discomfort for no apparent reason could be suffering from bloat (medically referred to as gastric dilatation and volvulus, or GDV), or from a number of other unrelated conditions. However, bloat is a life-threatening condition and a true medical emergency. Recognizing the signs of bloat is extremely important for any dog owner.

When bloat happens in domestic dogs, the stomach essentially becomes cut off from the esophagus on the one end (the tube from the mouth to the stomach), and the small intestine on the other (the tube from the stomach to the end of the digestive tract). The stomach distends with gas and for some reason can flip over to varying degrees, basically twisting and closing off the entry and exit passages for food and digestive contents. The gastric acids, gasses and digestive contents inside the stomach continue to process and expand fairly normally, causing the stomach to rapidly puff up like a balloon with nowhere for the gas to go. This in turn causes pressure on vital blood vessels, reduces the heart's ability to pump sufficient blood to organs and tissues, and ultimately causes the dog to go into shock from oxygen deprivation and very low blood volume and pressure. The stomach can rupture from the extreme pressure, which carries its own deadly consequences. Even if bloat is caught early and appropriately treated by either oral intubation or surgical intervention, many dogs will have cardiac arrhythmias which complicate their recovery. Unfortunately, recurrence is common.

Symptoms of Bloat
In the early stages, a dog that is "bloating" will be uncomfortable and edgy for no apparent reason. It will deteriorate rapidly. In no particular order, without treatment an affected dog will become increasingly restless, painful, weak and depressed. Its abdomen typically will become swollen, firm and excruciatingly painful. It may retch and try to vomit, but those attempts will be largely non-productive. Its breathing will become rapid, shallow and difficult. Its gums and other mucous membranes will become pale to blue, and it will salivate profusely. Its pulse will weaken while its heart rate races. Ultimately, without surgical intervention, the dog will collapse and die within a matter of a few hours. The most obvious physical signs of bloat are firm distension of the abdomen (a very hard, swollen belly), together with obvious abdominal discomfort. Non-productive retching and attempts to vomit are also common. Key clinical signs may include:

Firm, distended abdomen
Non-productive attempts to vomit
Retching
Restlessness
Weakness
Abdominal pain (looking at the belly, biting at it, whimpering, etc.)
Depression
Lack of appetite
Rapid shallow breathing (tachypnea); difficulty breathing (dyspnea)
Profuse salivation ("frothing at the mouth"; normally indicates severe pain)
Pale mucous membranes (gums, others)
Weak pulse
Rapid heart rate (tachycardia)
Collapse
Cardiac arrhythmias (abnormal heart rhythms)
Basically, if your large or giant breed, deep-chested dog is "off," is retching and trying to vomit but cannot, is restless, painful and salivating profusely, take him or her to your veterinarian immediately.

Dogs at Increased Risk of Bloating
Deep-chested, older, large and giant-breed dogs of either gender are at the greatest risk of developing bloat, although any dog of any age or breed can be affected by this deadly condition. Purebred dogs in these categories seem to be at an increased risk over mixed breed animals, and having a parent or sibling who has suffered from bloat also is associated with an increased risk of developing the disorder. Other risk factors include dogs with narrow and deep chests, once-daily feeding, rapid eating, exercise soon after eating, consumption of large amounts of food or water at one sitting, stress, low body weight and fearful temperament. Breeds commonly affected include the Great Dane, Weimaraner, Saint Bernard, Gordon Setter, Irish Setter, Doberman Pinscher, Old English Sheepdog, Standard Poodle and Bassett Hound.

Diagnosis & Tests

Introduction
Bloat, which is a medical condition called gastric dilatation and volvulus (GDV), is an extremely serious condition that can occur in any dog but is most common in older large and giant breed dogs with narrow, deep chests. It is not difficult for a skilled veterinarian to diagnose bloat (and/or torsion, a common accompanying condition where the stomach twists on its axis, blocking the entry or exit of accumulating gas).

How Bloat is Diagnosed
A diagnosis of bloat is made based on several factors. The breed and history will often provide a strong suspicion of bloat, if the patient is a large, deep-chested dog over 2 years of age with sudden onset of a distended belly and signs of abdominal pain. The physical exam will also often reveal the telltale signs of an enlarged abdomen, with severe abdominal pain and usually excessive salivation ("frothing at the mouth").

The onset of shock is diagnosed by the presence of pale mucous membranes with poor capillary refill time (normally assessed by looking at the dog's gums, touching them firmly with a finger and assessing how long it takes for them to go from white-ish back to pink), increased heart rate, and poor pulse quality. Radiographs (commonly called X-rays), are usually taken after the dog's stomach is decompressed via a tube inserted through the mouth down into the stomach, and/or by a needle inserted into the stomach through the abdominal wall, to release the abnormal gas build-up if at all possible. If the dog is bloating, the radiographs will show a stomach distended with gas. The pylorus, which is the opening between the stomach and the intestines through which food passes for digestion, will be displaced if the dog has a twisted, or torsed, stomach. This is clinically referred to as a "double bubble" sign on abdominal films and is diagnostic for gastric dilatation and volvulus. Only a veterinarian can confirm a diagnosis of bloat. Again, bloat is an extreme medical emergency, and it is not something to be addressed by the internet or in-home treatments.

Special Notes
Owners of large or giant breed, deep-chested dogs should be keenly aware of the symptoms of bloat. This is a life-threatening condition that can occur at any time or under any circumstances. It is very treatable if caught early.

Treatment Options

Introduction
When an owner sees signs that suggest bloat, they should take their dog to the hospital immediately. If left untreated, and if the dog is suffering from gastric dilatation and volvulus, the dog will die in almost every case. The goals of treating this condition are to resolve the shock caused by reduced blood flow in circulation (hypovolemia), to decompress the bloated stomach, to correct the position of the stomach surgically if it has torsed, to surgically remove devitalized or dying stomach, spleen or intestinal tissues as necessary, and to "tack" the stomach to the abdominal wall through a procedure called "gastropexy" to reduce the chances of recurrence of this condition.

Treatment Options
When a dog comes into the veterinary hospital with clinical signs of bloat, the veterinary team will unite to prepare for emergency surgery to save the dog's life. Typically, intravenous catheters will be placed to provide fluids for the dog to try to correct shock. Antibiotics may also be given. The bloated stomach may be decompressed by intubation (putting a tube through the mouth, down the esophagus and into the stomach, if possible), to provide an escape route for the accumulating gas). This is called orogastric intubation. If this is not possible or is unsuccessful, the veterinarian may attempt to relieve the gastric distention by a procedure called percutaneous trocarization of the stomach. Basically, this involves preparing the abdominal entry site and then inserting a large needle through the body wall into the stomach. If successful, there will be a hissing sound and foul-smelling gas will come out through the needle, much like "popping" a balloon.

When the stomach has actually flipped over, or torsed, surgery will be necessary to return the stomach to a normal position. There are several different procedures that veterinarians can use to accomplish this result. It may be necessary to remove the spleen as well, if it is involved in the twisting/torsion. When abdominal surgery is performed to correct the consequences of bloat, it typically is recommended that the surgeon tack the stomach to the abdominal wall via a procedure known as a gastropexy. This can greatly reduce the chances of a recurrence of GDV.

Owners should know that heart arrhythmias commonly occur within the first 36 hours after bloat surgery. Most veterinarians will want to keep the dog in the hospital for at least that period of time post-operatively, to monitor the heart's function.

Prognosis
Dogs who develop bloat (gastric dilatation and volvulus) and who are treated surgically still have an approximately 15% chance of dying. It the stomach (gastric) lining has already started necrosing (dying) by the time of surgery, survival rates are even worse. However, if caught early, and if a gastropexy is successfully performed, the chances of recurrence are slim.

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