Bloat Research Update

Rob Hilsenroth, DVM

Have you ever felt bloated? It’s a condition that many have experienced after eating – that uncomfortably full feeling in your stomach after a big meal or after eating foods that result in a lot of gas production. Bloat for us is unpleasant, but it’s usually a transient, uncomplicated condition.

Bloat in dogs, however, is a completely different condition, with very severe ramifications. In certain breeds of dogs, when the stomach fills with air, it can get so large that it can interfere with breathing, impede circulation, and result in shock. The episode doesn’t necessarily follow eating a big meal. In many instances, a bloated stomach can twist upon itself, causing a life-threatening condition known as gastric dilation and volvulus, or GDV. Regardless of what we call it, bloat or GDV, it’s a serious condition that requires immediate veterinary attention. For the rest of this article we’ll use the term bloat.

Canine bloat occurs most often in purebred dogs that have deep and narrow chests and abdomens. Such breeds as Great Danes, Irish Setters, Saint Bernards, Doberman Pinchers, and Basset Hounds top the list of those at highest risk for developing bloat.

Canine bloat is a distressing disease for dog and owner alike. It often happens to dogs that are otherwise normal and healthy. The onset of the condition is sudden and very painful for the affected dog. Bloat can occur at any age, but older dogs tend to be affected more often. Canine bloat should be considered an emergency situation.

What causes canine bloat?

The exact cause of bloat in dogs is unknown. The reasons why and when bloat is likely to happen are questions that scientists are still trying to answer. Veterinarians believe that bloat is probably caused by several different factors. The most consistent finding is its occurrence, as mentioned above, in dog breeds with deep, narrow chests. Inherited or genetic traits may account for part of a dog’s risk of developing bloat.

Any of a large number of circumstances that can result in excessive amounts of gas or air in the stomach can also con-tribute to canine bloat. Many veterinarians believe that dogs who consume their food ravenously, or those who consume large amounts of food or water at one time are at higher risk of bloating, although this has not been proven.

Swallowed air also contributes to the amount of air in the stomach. Large amounts of air in the stomach may cause it to rise into an unusual position that can lead to the stomach twisting upon itself. This twist of the gas-filled stomach will cut off the vital blood supply to the affected portion of the stomach and cause death unless the twist is corrected.

What are the signs of canine bloat?

The most noticeable sign of bloat is a rapidly enlarging midsection, right behind the rib cage. This enlargement takes place over a period of minutes to hours. Some dogs, however, don’t show any swelling, but will look and act uncomfortable. Most dogs usually have pain in the abdomen, and may walk around with difficulty. Unproductive vomiting, pale gums, and a rapid heart rate with weak pulse rate are also common signs of bloat.

How is canine bloat diagnosed and treated?

The initial diagnosis of bloat is usually made on physical examination by the veterinarian, and it can be confirmed by abdominal radiographs. Passage of a gastric tube is a procedure that can be both diagnostic and therapeutic. It can confirm the presence of gas trapped in the stomach, and it can help to relieve the pressure in the stomach. If the tube can’t be passed all the way to the stomach, it’s often an indicator that a torsion has occurred.

To treat a dog with bloat, the veterinarian must first correct the shock that is present and is the most life-threatening situation. Shock follows the compromise of the circulatory system and the inability of blood to reach the vital organs.

To treat this condition, large amounts of fluid must be administered intravenously to increase the circulatory blood volume. Next, the stomach must be decompressed. If this can’t be accomplished with the gastric tube, a procedure called trocharization is attempted. This involves inserting a large needle directly into the stomach through the body wall. This will have an effect similar to that of letting the air out of a big balloon and will provide temporary relief.

The definitive treatment for bloat is surgery to correct the twist and remove any portion of the stomach that may have been irreversibly damaged. If the stomach has ruptured due to excessive stretching, the prognosis for recovery is extremely poor.

Given the propensity for some dogs to bloat, most surgeons will perform a technique called a gastropexy when they correct a twisted stomach. This procedure affixes the stomach in place by attaching it to the abdominal wall. The aftercare of the bloat patient is also extremely important. Dogs must remain hospitalized with fluids for several days before they can gradually be reintroduced to solid foods.

What is being done about canine bloat?

Morris Animal Foundation recognizes that bloat is a serious condition that happens frequently in many dog breeds. The Foundation is currently sponsoring the study “Prospective Study of Morphometric, Genetic, and Dietary Risk Factors for Bloat” by Dr. Larry Glickman at Purdue University School of Veterinary Medicine.

Dr. Glickman and his colleagues are investigating the influence of factors such as diet, heritability, and body structure of several high-risk breeds for canine bloat. Dr. Glickman’s efforts will provide valuable knowledge to breeders and owners about the factors that may cause bloat in dogs at high risk for developing this dreadful condition.

Cosponsors of this study are Morris Animal Foundation, the AKC Health Foundation, “Piedde Boue” Working Bouviers (in memory of Chelsea), and the Hill’s Mark L. Morris Lifetime Achievement Award honoring Anne Rogers Clark.

Rob Hilsenroth, DVM, is Executive Director of Morris Animal Foundation. This nonprofit organization sponsors animal health studies at veterinary schools and institutions throughout the U.S. and in other parts of the world. All annual unrestricted contributions to the foundation support health programs – not the cost of administration or fund-raising.

If you’d like to make a contribution, write Morris Animal Foundation, 45 Inverness Drive East, Englewood CO 80112. For more information, call (800) 243-2345.


Bloat Update

Debbie Eldredge, DVM

Canine GDV (Gastric Dilatation/Volvulus), or bloat, is now  considered a problem involving many factors: environmental factors such as stress and genetic factors such as conformation.

Much study has gone into the treatment of bloat. With the exception of some variations in the methods of stabilizing the stomach and the now widely accepted feeling that surgery should always be done and as soon as possible, no real breakthroughs in treatment have occurred over the past 10 years. Mortality from GDV still averages about 30% nationwide.

It makes sense to now try and determine risk factors for bloat and see if we can prevent it. For a while, it was felt that a dog’s diet influenced his chances of developing bloat. Dry foods (especially those with soybean) were suspect. A problem here is that most of the dogs bloating are large breeds and, therefore, eating dry foods. However, so were plenty of large breed dogs that didn’t develop bloat. At this time, the actual diet seems to be a minor factor, if indeed it matters at all.

Feeding one large meal a day, especially if your dog then takes a big drink, may be a contributing factor. It is also felt that vigorous exercise right before or after eating, which leads your dog to pant and possibly gulp air, might help lead to dilatation. Stress is a factor in almost any health problem and GDV is, most likely, no exception.

Dr. Larry Glickman, VMD, heads a research team at Purdue University which is studying bloat under a grant from the Morris Animal Foundation. They’re looking at risk factors in an attempt to predict which dogs might have trouble. They’re also looking at how, if possible, to prevent that trouble from occurring. While the study is still ongoing, there have already been some interesting developments.

Certain breeds are notorious for having an increased incidence of bloat. Many of these are big dogs such as Great Danes, German Shepherd Dogs, Irish Setters and Doberman Pinschers (including a Best in Show at Westminster winner). But Bassets and Dachshunds also make the list. Dr. Glickman’s team feels that chest conformation may be a deciding factor. Many of the high risk breeds have deep, narrow chests. This may affect the ligaments that hold the stomach in place.

Chest radiographs (X-ray pictures) of dogs with bloat and control dogs (matched by breed and approximate weight) will have special measurements checked. This is to see if certain chest depth/width ratios could predict bloat risk.

Bloat is primarily associated with big dogs. But within a weight class, such as 75 to 100 lb. dogs, breed does seem to be a risk factor. For example, an 80 lb. German Shepherd Dog has a much greater risk of GDV than an 80 lb. Golden Retriever. This difference may come down to chest conformation. It may behoove breeders of high risk breeds to choose breeding stock with wider chests if this study continues to bear this theory out.

There is another Purdue study just starting up, again funded by Morris Animal Foundation. Purdue veterinarians are asking other veterinarians to send information on bloat cases and matched controls from their practices.

The data will include chest dimensions. In addition, owners of bloat cases will be carefully interviewed to determine if their dog’s management (including diet factors) may have contributed to the problem. Seventy-five cases will also be followed for one year to see if changes in management or different treatments might make a difference in survival rates.

If you’ve ever lost a beloved dog friend to bloat or have a friend who has, a wonderful memorial would be a donation to bloat research in that pet’s name. One of the best ways to do this is to send money to:

Morris Animal Foundation
45 Inverness Drive East
Englewood, CO 80112

Note on your check that it is for the canine bloat study.

For further reading on bloat, send a stamped, self-addressed business-sized envelope to:
Canine GDV Research Program
Bloat Notes
School of Veterinary Medicine
Purdue University
West Lafayette, IN 47907-1243

or to:
Ralston Purina
P.O. Box 88988
St. Louis, MO 63188
Ask for a copy of Understanding GDV (Bloat) in Dogs.

Bloat: Not Just A Stomach Ache

Debbie Eldredge, DVM

Among dog people, bloat is the  common name for the medical  problem gastric (stomach) dilatation-volvulus, or GDV. Not only is bloat a complex problem, but it can be a fatal one as well. Certain breeds appear to have a higher risk, and environmental factors can play a part, too (see the accompanying article).

In a case of bloat, the stomach becomes greatly distended. Usually, there is a combination of air, food and water, often with foamy bubbles as well. As the stomach distends, pressure is put on ligaments that connect the stomach to the liver and spleen holding it in place. Eventually the stomach rotates.

With the rotation, or volvulus, the dog’s condition becomes much more acutely critical. The rotation physically closes both the entry and exit from the stomach. The dog now has no chance of relieving the distended stomach by vomiting or having the materials pass on into the intestines. The pressure from distension alone can decrease blood flow to the tissues of the area, and the volvulus can actually stop blood flow. Without the flow of oxygen and nutrients from the blood, many tissues will become necrotic and die.

Severe shock, both from blood volume and oxygenating problems, as well as sepsis (infection) will soon occur. Death will result if the situation is not corrected.

Treatment can be as complicated as the bloat itself. The first necessity is to decrease the distension of the stomach, relieving the pressure on the blood flow. Your veterinarian will first try to pass a large tube down your pet’s throat, through the esophagus and into the stomach to allow the excess gas to escape.

In plain gastric dilatation, this may bring immediate, complete relief. More commonly, the tube will be unable to pass into the stomach due to a volvulus. In those cases, your veterinarian will probably relieve the pressure by carefully placing 1 to 3 large, sterile needles directly through the body wall into the stomach. The gas will frequently escape with a loud hiss.

Once the stomach is decompressed, your pet is out of immediate danger. Your veterinarian will try to pass the tube again and, if possible, empty the stomach by flushing into the tube, and may even put some medications directly down the tube into the stomach.

Treatment for shock must also be started right away. This usually consists of IV (intravenous) fluids, antibiotics and, depending on your dog’s individual case, possibly steroids.

It is now generally felt that surgery should be done in most bloat cases and as soon as possible. Surgery allows your veterinarian to directly examine the stomach and the spleen for any necrotic lesions, to remove any dead tissue which could serve as a source of toxins and infection and to do one of a variety of corrective surgeries that will help to prevent a recurrence of the whole dilatation/volvulus complex.

In a typical medical Catch 22, problems can arise even as you are fixing the volvulus. (Remember, however, if this condition is left untreated, your pet will die.) If the stomach has been twisted for any length of time, toxins are released from the oxygen-starved tissues when blood flow returns. For this reason, your dog will be carefully monitored after the surgery for infection, continuing of shock, and heart arrhythmias.

Lisa is a very knowledgeable dog owner who is particularly careful about bloat. She has German Shepherd Dogs, which are a breed prone to this problem, and she lost one of her dogs to bloat about two years ago. This was despite her taking the standard bloat precautions – feeding two meals a day, keeping her pets quiet both before and after meals, and always having fresh water available.

Lisa came home from work in May of this year and found her 7 year old neutered male German Shepherd Dog, Blue, attempting to vomit. His abdomen was distended, too, and Lisa knew right away what was happening. She called our clinic and reached Dr. Stas Demson, who was on emergency call. He had her drive right over – bloat is a definite emergency!

Blue was still in decent shape because Lisa caught him early on. An IV catheter was placed and he went right into surgery. At surgery, it was determined that his spleen had torsed (twisted) also and this was causing his stomach dilatation. I find the involvement of the spleen particularly common in German Shepherd Dogs, and sometimes the spleen has the cancer hemangiosarcoma. Blue’s spleen was damaged, so it had to be removed.

Luckily, none of his stomach was necrotic. After removing the spleen, Dr. Demson then did a surgery called a gastropexy, where the stomach wall is actually sutured to the body wall. This greatly reduces the chances of the stomach being able to flip again in the future. Without a surgery such as this, the rate of recurrence in bloat is very high.

Blue was fortunate – Lisa caught his problem early, he was treated right away, and he avoided the post-operative complications of infection or heart arrhythmias. In fact, by the next morning he felt good enough to remove his own IV catheter!

Blue went home two days later on antibiotics, multiple small feedings and drinks daily, and strict confinement – with leash walks only – until his stitches came out ten days later. This German Shepherd Dog was one of the lucky ones!