Gastric-Dilatation-Volvulus, or GDV and colloquially known as “Bloat,” is a severe, life-threatening condition that affects large, deep-chested dogs, and is always a surgical emergency.
How Bloat Starts
Bloat occurs when the stomach gets stretched out and then twists 360 degrees on its long axis. Picture the stomach as nothing more than an out-pouching of a long, skinny tube. That tube is the GI tract – it enters the stomach via the esophagus, and leaves the stomach as the duodenum, the first section of the small intestine. So with the stomach being just an out-pouching of this long tube, if it twists around the axis of the tube it closes off the entry and exit into the stomach at each end. When this happens the gas that is naturally produced in the stomach has no place to escape. This causes the dilatation in the name Gastric-Dilatation-Volvulus. Besides twisting on the long axis the stomach also flips so that the exit and entrance to the stomach essentially change place. This is the volvulus that is referred to in the name, as well. So with the entrance and exit to the stomach closed off and flipped around, nothing but bad things happen next. The first thing that happens is that the stomach fills with gas over the course of the next few hours. This causes the “bloat” most people refer to. This bloat causes intense pain, and also partially blocks the return of venous blood to the heart via the vena cava. This causes the dog to start to go into hypovolemic shock. At the same time, the buildup of gas and acid in the stomach causes extreme disruptions in the electrolyte and acid-base status of the dog. This electrolyte disturbance also causes cardiac abnormalities including severe arrhythmias. Left unattended the pet usually dies in less than 24 hours.
Signs of Bloat
The first sign that an owner will see is that the pet acts like they need to vomit, but can’t. They can’t vomit because the entrance to the stomach is twisted shut, so nothing can pass back up the esophagus to exit. This often presents to the owner as a large amount of salivation and retching action, but with no production of vomit. These signs present usually within one hour of the stomach twisting. The second sign the owner will see is extreme depression. The dog will be reluctant to move and often stands with a head down position, salivating heavily. This will present within 90 minutes of the stomach twisting. At that point the stomach will start to inflate to a size that will now be noticeable to an observant owner. The abdomen will be distended and hard, and oftentimes the pet will wince when palpated. At this point the owner has precious little time to get the pet to the veterinarian. At one lecture I went to on this condition the surgeon discussing it had done a study of approximately 80 bloats he had seen. By his calculation the dog has an approximately four hour window to get to surgery to have a decent chance at survival. Essentially his point was that after four hours of torsion the dog has a less than 50:50 chance of survival. The diagnosis of bloat on our end is fairly straight forward. I feel a hard structure in the abdomen, take an x-ray, and there is a specific sign we see on the x-ray called the Reverse-C sign in the stomach. (See accompanying x-ray). When that sign is present it’s a 100% confirmed case of GDV, and immediate surgery is indicated.
Surgical Correction of Bloat
The surgery is relatively challenging. The textbook recommends passing a stomach tube to decompress the stomach first, but it’s been my experience in every GDV surgery I’ve done that passing the tube is all but impossible due to the twisted entrance to the stomach, and essentially just wastes time that the dog doesn’t have. So I now always take the dog straight to surgery and decompress the stomach with a large-bore needle once I have the abdomen open. Once the stomach is decompressed I can then de-rotate it and reposition it in its normal position. At that point we pass a stomach tube to further decompress and evacuate gas and gastric contents. Once the stomach is back in place and decompressed the stomach needs to be tacked to the abdominal wall to prevent the condition from recurring. There are many ways to accomplish this, and each surgeon has their preference. I do mine with multiple large-gauge non-absorbable sutures to ensure that the stomach doesn’t release from the wall. In addition to decompressing and de-rotating and tacking the stomach, sometimes other surgical measures need to be taken as well. In many bloats the spleen is involved in the torsion and can suffer severe ischemia (lack of blood flow). When this happens, the spleen must be removed to prevent further post-surgical complications. And in extremely rare instances part of the stomach can also become ischemic. In that case the surgeon has to make a judgment call as to whether to resect the effected part of the stomach. This is a good prognostic indicator that the pet is in extremely critical condition. Post surgery complications can be many, and the pet should be hospitalized for several days after surgery to make sure any complications can be addressed. I always warn my clients that the dog can still die up to 48 hours post-surgery. This arises because of the severe electrolyte and acid-base disturbances that occur during the bloat. This is one of the big reasons why time is so critical in getting the pet to surgery. There are many theories as to what causes bloat in dogs. Many things have been researched, including feeding the dog with an elevated food bowl, or feeding specific diets. However, the latest lecture I attended on bloat presented convincing evidence that the problem is with the dog eating and especially drinking too much at once. Think of a water balloon that’s over distended with water. Picture holding that balloon by the knot and letting it hang, and how that severely strains the neck of the balloon. In dogs there is a ligament that runs from the outflow of the stomach to the abdominal wall, called the gastro-phrenic ligament. When the stomach gets over-distended with water it strains this ligament just like the neck of our water balloon. This allows the stomach to get out of position, and gastric-dilatation-volvulus ensues. So the recommendation for owners with large, deep-chested dogs (e.g. Great Danes, German shepherds, Dobermans, greyhounds, etc) is to feed smaller meals more frequently, don’t allow the pet to gulp down large volumes of water, and do not allow the pet to be exercised or allowed to run for a minimum of one hour after they eat. And most importantly – if you even remotely suspect something’s wrong with the dog’s abdomen – get to the vet immediately.