There are dog owners, breeders and even veterinarians who use these three terms interchangeably. Although they often do occur together, they are not all the same thing.
Bloat just means an enlarged stomach - distended with gas or food. In the least threatening situations, that just means the dog ate too much or consumed dry dog kibble, which then increased in volume when the pet subsequently drank water.
Although gastric dilatation (= an enlarged stomach too) (GD) could describe the same situation, veterinarians usually use that term to describe a situation where, for one reason or another, the dog’s stomach is having difficulty propelling food from its stomach into its intestine.
Volvulus, also called gastric dilatation and volvulus (GDV), is a situation where the stomach has flipped over on itself, blocking the normal entry and exit of food. It is the most serious of these three situations. It is life threatening if not attended to promptly. As pressure builds up in the dog's trapped stomach, blood can no longer circulate normally through the stomach walls, Cells are injured, toxins are liberated and dangerous changes in blood composition occur.
I am going to tell you about gastric dilatation and volvulus (GDV) first because it the most serious of the three conditions and because it brings the most worried readers to this page. GDV is one of the life-threatening condition that large and giant dog breeds are most likely to experience. Large breeds with deep narrow chests are also at higher risk. (ref) Some state that the chances of GDV occurring in the lifetime of a giant breed dog is 24%; in a large breeds, 47%. (ref) Others have estimated the likelihood about half that. Likelihood aside, when GDV strikes, it tends to be in the dog’s middle aged and geriatric years.
Veterinarians do not see a lot of GDV cases - but when they do, they have to work diligently and rapidly if they are to save your pet’s life. Dilatation just means enlarged or stretched. A volvulus or torsion is a twisting of an organ revolved around its longer axis – like a baggie half filled with water and suddenly flipped by the corners. In this sort of situation, the stomach expands with trapped air and fermentation gases that can no longer escape forward through belching or pass rearward through the intestine. In this stretched and often twisted condition, vital blood circulation to your dog’s stomach and spleen can be restricted or cut off. The massively enlarged stomach, pressing on the pet’s diaphragm, also prevents normal breathing. (ref1, ref2)
Cases of only a gas filled, enlarged stomach (GD) without twisting do occasionally occur. In those situations, your veterinarian can find no evidence of a volvulus or torsion – only an inability (for reasons unknown) of the pet to rid its stomach of food and trapped gasses. That (GD) diagnosis is often made on the basis of the veterinarian still being able to easily pass a stomach tube down your dog’s throat and into its stomach and confirm the tubes placement using ultrasound or x-rays. In GDV, the tube would encounter the “flipped over” stomach and find no entry.
A classical case of GDV begins quite suddenly - often shortly after your dog consumed a large meal. The first signs you might notice in your dog are anxiousness, restlessness and a disinterest in its usual routines. That is because of the abnormal fullness that is developing in its tummy.
Many dogs begin to pant as their enlarging stomach presses on their diaphragm. They might look or lick at their abdomen, stand with their front legs wider apart, drool, salivate and make failed attempts to vomit, heave and retch. At the most, foam and mucus is all that comes up.
As time goes by their abdomen continues to enlarge. It becomes tight and hard, usually causing them discomfort or considerable pain. If these dogs are not brought to your veterinarian soon, the problem often progresses to weakness, collapse and shock. That is why so many of these cases end up at urgent care 24-hour clinics. By that time, the dog’s gums are often pale and their pulse weak and rapid. Those are all classical signs of shock.
Many problems can cause abdominal enlargement in dogs. But few, other than GDV, come on so suddenly and produce such severe signs. It is often the dog’s lower left side (abdomen) that is most enlarged and firm.
When dogs in this state are radiographed (x-rayed), their gas-filled, enlarged stomach is usually quite apparent. From the position of the gas bubble(s) within it, your vet can often get a good idea if the stomach has flipped over into an abnormal position (volvulus) or if it is just distended (simple bloat (= FE) or dilatation). Read about simple food engorgement or FE at the bottom of this page. The inability of stomach tube, passed down the throat, to enter the stomach helps confirm a GDV problem.
As the problem progresses, laboratory examination of the dog’s blood often confirms metabolic acidosis. It is also common for blood potassium in these dogs to be low. Low blood potassium can affect your dog’s heart rhythm and cause muscle weakness. Blood plasma lactate levels are often increased too. The degree (amount) of elevation often parallels the severity of the case. (ref)
There are other diseases that can have similar symptoms. Your vet will want to rule them out too. One is under-performing adrenal glands (Addison’s disease). Various tumors, spleen or intestinal torsions (twists), intestinal obstructions, hemorrhage, and diaphragmatic hernias might also need to be ruled out.
Yes. It is.
Time is of the essence in getting your dog to your veterinarian. All owners of dog breeds in which GDV commonly occurs need to think ahead. Find out where the nearest 24 hours emergency animal hospitals are in your areas before you need them. Look into their reputations and cost structure. Then tape their phone numbers on your refrigerator. Enter them in your cell phone. Sudden weakness and discomfort in your pet - with no logical explanation - is always an emergency. The most important factor in the survival of dogs with GDV is the speed with which the problem is addressed.
The first job of your veterinarian is to stabilize your pet’s blood circulation. That treatment often requires intravenous fluids and medications to counter shock. Read about the various techniques and medications that are used in GDV cases in detail here.
Supplemental oxygen might be required. If the gas pressure in the stomach cannot be relieved by other means, emergency surgery to return the dog’s stomach to its proper position is often required. But the chances of successful recovery from surgery are best when the dog’s general condition can be stabilized before the surgery begins. Often, attempts will be made during that surgery to prevent the dog’s stomach from ever shifting or twisting again. Read more about that procedure, called gastropexy, farther along in this article.
No veterinarian can explain that to you with certainty. Although we have observed the problem for more than 100 years, veterinarians understand quite little about the underlying dynamics that cause it to occur.
We know your dog’s genetics plays and important part. We know that deep chested and large-bodied dogs are at greater risk. We know that the chances of GDV increase with age. But the underlying causes lie deeply buried in your dogs “second brain” its autonomic nervous system.
The autonomic nervous system is the part of your dog’s brain that controls unconscious activity. That includes the actions of the muscles that propel food through the digestive system. (ref) Besides the digestive system, the autonomic nervous system controls most of the body functions one does not conscious think about – things like blood pressure, heart beat and breathing rate. The highway that leads from its command center in the brain (the hypothalamus) to your dog’s digestive system and stomach is a branch of the dog’s vagus nerve.
GD is a gastric motility issue - a slow down in the ability of your dog’s stomach to rhythmically pass food from its stomach to its intestine. (ref) Some call this delayed gastric transit time. It probably occurs considerably more frequently in elderly dogs than we realize. Similar slowdown occurs in older humans and older animal models as well. (ref1, ref2, ref3, ref4) The medical term for these malfunctions of the autonomic nervous system is dysautonomia. Since the system can malfunction in a large number of ways, cases of GDV that veterinarians lump together today as a single disease probably have many different underlying causes. For instance, stomachs that are contracting normally and convening your dog’s food adequately will still over-fill (=GD) if the stomach’s pyloric valve fails to open. Relaxation of your dog’s pyloric valve is another function of its autonomic nerves. The signaling mechanism is very complicated and can fail at many points and for many different reasons. (ref1, ref2, ref3)
Another hint that underlying autonomic nerve problems are the source of GDV is that the breeds of dogs that have the highest incidence of GDV are the same breeds with the highest incidence of megaesophagus. Proper contractions of the esophagus are also under the control of the dog's autonomic nerves. Dogs that suffer from megaesophagus are at increased risk for GDV as well. (ref) Human studies tend to confirm this. (ref)
When your dog’s digestive system is not conveying food properly throughout its length, other things occur. One of them is a change in the species of bacteria and fungi that find your dog’s intestinal tract hospitable – its intestinal biome. Past studies indicate that dogs that are prone to GDV-type issues are also more prone to inflammatory bowel disease (IBD). IBD has also been associated with changes in the type of bacteria that inhabit your dog’s stomach and intestines (its gastrointestinal tract). (ref) The condition is called dysbiosis. (ref)
In 2017, researchers in Seattle WA, knowing that Great Danes are highly prone to GDV, explored the possibility that the dogs that experienced GDV were, in some way, genetically different from those that didn’t. Their results appeared to show that the immune systems of the dogs that experienced GDV were having problems telling the difference between “good” bacteria – necessary for proper stomach emptying – and “bad” bacteria that inhibited the process. If that imbalance in bacteria is the cause or the result of GDV and IBD remains to be explored. You can read there study here and a commentary on it here.
We know that age also changes the dynamics of the intestinal immune system as well as the ability of the stomach and intestines to propel food as it should. (ref) But other veterinarians suggest that the reason GDV affects older dogs is that, with time, the ligaments that support your dog’s stomach become flabby and allow the organ to flip over. Particularly when your dog is deep chested.
On occasion, gastric misalignment or volvulus occurs as a chronic, non-emergency condition. When it does, the signs of the problem are much less dramatic or specific. They include weight loss, inactivity, chronic vomiting and abdominal pain. (ref) Occasional cases of GDV progress more slowly and less typically, resulting in an abnormal position for the stomach and chronic indigestion.
No one has found medications that are effective in preventing GDV, GD or simple Bloat in dogs. There has been work in developing drugs that promote stomach emptying (decrease gastric transit time) in humans; but the results have not been breathtaking. (ref) If some GDV cases are due to pyloric valve spasm, perhaps sildenafil might be helpful. It appears to be in megaesophagus. (ref) I do not know of its prior use in dogs for GDV or GD and I would be very hesitant to give a bloat-prone dog that medication if abnormally high pyloric valve tone had not been adequately documented.
I think that the most important thing you can do to lessen the risk of GDV is to divide your dog’s daily food intake to multiple smaller meals throughout the day. Canines where designed by Nature to eat as much as possible when food was available to them – what wild canine knew when food might be available to them again? That’s not how our dogs live today. Many of today’s dogs have the opportunity and ability to eat in one sitting, amounts of food that are not healthy for them. US military guard dogs were fed once a day throughout the 1990s. Among those dogs, GDV was the 5th most common cause of death. (ref) In the rhesus monkeys I once cared for, once-a-day feeding of dry kibble commonly caused fatal bloat as well.
Some owners of GDV dogs have described their pets as “greedy” eaters. I do not know if that is generally true. (ref) There are even veterinarians who believe that it is possible that the weight of large meals stretch the ligaments that would normally prevent a dog’s stomach from “flipping” over (volvulus) (ref) Some stretching of that ligamental system also occurs during normal aging.
Some breeders believed that heavy exercise just before or after eating can bring on GDV. I do not know if that is true. But others have found that moderate exercise before and after meals was actually beneficial. (ref1, ref2)
Many believe that a diet of dry dog chow is more likely to cause GDV that a diet or fresh or canned food. According to that theory, dogs tend to drink a large amount of water subsequent to consuming dry kibble. The kibble swells and the stomach inflates. In my opinion that, in itself, is more likely to cause the “simple bloat” discussed at the end of this article that GDV. But I cannot tell you that with certainty either.
A Purdue University study suggested that feeding your dog from a raised bowl increased its chance of developing GDV. Most folks who feed their dog from elevated dishes are doing so because of megaesophagus/swallowing issues. Since GDV and megaesophagus have the same autonomic (nervous) dysfunction as their underlying cause, I do not think that the raised bowls were the true cause of GDV. We know that megaesophagus dogs are at greater risk of developing GDV. They also found that high fat content food, citric acid and pre-moistening the food also increased GDV risk. High meat-content dog foods tended to decrease GDV risk. Those authors suggested that withholding water for about an hour before and after meals might be helpful. You can read that study here.
Two studies I know of linked GDV to the size of food particles – finding that dogs fed a coarser chunk meat diet was less likely to experience GDV than ones fed a fine particle diet. (ref1, ref2) I have always been a fan of cooking at home for your dog. Doing so lets you control food consistency as well as ingredients. Read about that here and here.
Others have found that having fats or oils within the first four ingredients listed on a dry dog food label appeared to increase the chances of GDV in dogs. (ref) Dietary fat is thought to slow stomach emptying. And studies in laboratory animals tend to back that up. (ref1, ref2) So I would feed my GDV-prone dog a low fat diet. Fat is not a necessary nutrient for dogs. How the fiber content of a diet affects your dog’s gastric emptying time remains unknown.
Breed, family history of GDV or a history of megaesophagus, swallowing or IBD problems increase a dog's risk for GDV. But I would also be cautious in my feeding choices and schedule if your dog is predisposed to gagging, throat (laryngeal) problems or coughing after drinking because the same autonomic nerve centers involved control the stomach. (ref)
When your veterinarian must perform surgery to get the twist out of your dog’s stomach and remove the gas and debris that are distending it, your vet will almost certainly ask your permission to attempt to make it impossible for the problem to reoccur in the future. That surgical technique is called a gastropexy. It involves creating a scar between your dog’s stomach wall and its nearby abdominal wall. The technique differs based on the preference and training of your veterinarian, but all techniques remove the slick protective surfaces from a small portion of your dog’s stomach and a similar size area on its right abdominal wall. Bleeding surfaces, sutured together, will heal as one unit. So, with time, the dog’s stomach can no longer slide about as freely in the dog’s abdomen. In critically ill dogs, irreparably damaged portions of the stomach and even the spleen might have to be removed as well. There are many surgical techniques. Read about some of them here.
One report suggested that greater than 80% of GDV dogs will experience a future GDV event and die with in a year if a gastropexy is not performed. (ref) When dogs are just too weak to tolerate the extended surgical time required to perform the gastropexy, a second operation to do so can be postponed until your dog is stronger. At that time, the gastropexy can often be performed through two much smaller incisions. (ref)
There are veterinary surgeons who suggest that all dogs of high-risk breeds receive a prophylactic (preventative) gastropexy. I believe that in most cases, that is an over-reaction. Do consider it when siblings or parents of your dog developed GDV while being fed and maintained in the ways I suggested. When circumstances exist in your life that prevent you from supplying your dog a lifestyle that lowers GDV risk, you might consider a prophylactic gastropexy for your pet as well. If your personality demands that the risk of GDV be close to zero, consider it as well.
It doesn’t take the complex issues I have been discussing until now to cause a dog’s stomach to be too full. Simple gluttony plus the swell-potential of the things dogs eat are sufficient to cause a severe tummy ache - or worse. Dry dog chow is 6-10% water (moisture content). The natural diet of carnivores, lean meat, is about 80% water. When your dog fills his/her stomach with dry kibble and then drinks water, that dry kibble is going to swell considerably.
Gastric dilatation/volvulus (GDV) and gastric dilatation (GD) are not the common condition of puppies and adult dogs that simply overeat and end up with a bloated abdomen and a severe tummy ache. Most dogs that arrive with a history of food engorgement can be treated conservatively once GDV and neurogenic GD have been ruled out. Read more about "simple" food engorgement here and here.