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Report: Dog Bloat – A Disease That Kills

Shortly before 3 o’clock on the morning of August 5, 2007, Donna Hedl was jolted awake by shouts of her niece and nephew, who were visiting Donna and her husband Joe in their Roselle, Illinois, home.

Something was wrong with Congo, the family’s six-year-old German Shepherd!

“He was retching, but to no avail,” Mrs. Hedl recounted later. “There was a slight foam around his mouth and he was constantly swallowing.”

As she watched, Congo’s behavior became more peculiar. The dog would sit glassy-eyed and hang his head, or crawl behind a chair and stoop as if to defecate… but, again, to no avail.

Then Mrs. Hedl noticed a slight swelling in Congo’s abdomen.

“My first thought was bloat… but of course that just couldn’t happen to my dog,” she said. “Besides, the last time he had eaten was more than twenty-four hours earlier.”

When she called the animal hospital in nearby Dundee at 3 a.m., Mrs. Hedl said that the dog had been poisoned, an assumption based on the fact that the Hedl’s yard had recently been sprayed with weed killer. But when she mentioned the abdominal swelling, she was told to bring the dog to the clinic immediately.

Within an hour, Congo was under the glaring lights of an operating table and the Hedl’s original fear had been confirmed. The dog was suffering from acute gastric dilatation – bloat.

Congo’s experience was by no means unusual. He was just one of the thousands of dogs that are stricken by bloat each year.

(Some veterinary authorities claim that more than 60,000 dogs per year in the United States have attacks of bloat. That’s nearly 200 dogs per day. Others put the estimate even higher, claiming that many dogs die of the disorder annually.)

Strike Two

Although Congo was saved by the prompt work of Dr. Raymond Norlin and Dr. David McLaughlin, the Hedl’s troubles did not end with just the bill for surgery.

On November 4, nearly three months to the day after the first incident, Congo had a second attack. The circumstances and symptoms (beginning with dry vomiting) were almost identical to those of the first episode. It was late at night and the dog had not eaten since midnight of the previous day – and then only about two cups of a commercially prepared dry dog food.

“I tried getting him to drink water, hoping he had something caught in his throat,” Mrs. Hedl said, “but knowing that wasn’t what was wrong.”

By the time the Hedls rushed Congo to the clinic he “looked like he was in whelp with twenty pups.”

After being unable to pass a stomach tube or stimulate the stomach muscles with drugs, Dr. Norlin and Dr. Roger Yates were again forced to operate. They found a stomach solidly packed with pasty, partially digested food, and swollen so much that the stomach wall was badly torn.

The veterinarians repaired the damage as best they could, then kept the dog under observation for three days.

(Congo has had more corrective surgery than you can imagine. In addition to the two bloat operations – the first requiring removal of the spleen and the second leaving a foot-long external scar – the dog has had the pectineus muscle in one leg severed and the ball of the hip removed to relieve hip dysplasia, and had two growths removed in another operation.)

At last report, Congo was home with the Hedls, romping and playing as if nothing had happened – but restricted to a special diet and constantly under the watchful eye of his owners, who fear another attack would kill him.

Searching For Answers

Congo was one of the luckier ones. Many dogs do not survive their first bloat attack; fewer still make it through a second. What causes such tragedies and what can be done to prevent them?

At present, neither question can be adequately answered.

In June of 1976, a panel of eight scientists from various areas of veterinary and human medicine met in Denver to discuss these questions and to plot a course for future investigation of the disease.

The panel was organized by the Morris Animal Foundation, which has given canine bloat research high priority and has established a special Bloat Fund to finance it. Though disagreement did exist among the scientists on that panel, a number of observations about bloat can be drawn from the discussion:

Acute gastric dilatation seems to be most prevalent in the larger breeds – Great Danes, German Shepherds, Irish Setters, etc. - although it has also been seen on occasion in the smaller breeds. It has been suggested that the depth of the chest, rather than the actual body size, is the factor that makes certain breeds particularly susceptible.

Congo’s case notwithstanding, most bloat attacks follow a big meal and the consumption of large amounts of water. For some unknown reason, the food does not pass normally through the digestive system, but remains in the stomach.

(Congo’s small dinner remained in his stomach, slowly swelling, for more than 24 hours; the stomach normally empties within 8 to 16 hours.)

Many bloat cases include a twisting of the stomach, which pinches off the escape routes of the digestive material. However, this twisting is more often the result of bloat than a cause of it, since many instances of gastric dilatation involve no twist.

The first hint the dog owner has that something is amiss would probably be a look of discomfort and restlessness in the dog. The dry vomiting and swelling that Mrs. Hedl described would soon follow.

Exactly What Is Happening To Your Dog?

It is critically important that the dog receive prompt medical attention if these symptoms occur. The stomach can quickly swell to the size of a basketball, damaging and straining many body systems and increasing the likelihood of future trouble.

Let’s trace the changes that can take place in a dog’s body during an attack of bloat accompanied by twisting of the stomach:

As the stomach swells with gas, it begins turning on a longitudinal axis, always in a clockwise direction. This initial twisting – called torsion – is dangerous, but not as critical as the stage it could lead to. That is volvulus, a clockwise turning of the stomach on a vertical axis.

(If the stomach were pictured as a football lying lengthwise in the body cavity, torsion would be analogous to a spiraling turn, while volvulus would resemble an end-over-end motion.)

The distortion of the stomach shuts off the openings at each end, like putting kinks in a garden hose. This traps food and prevents the escape of gas (which is normally not a major byproduct of digestion in the stomach, but seems to be produced in gastric dilatation cases.)

The spleen, which normally lies to the left of the stomach, is carried around to the right abdominal wall. Although the blood flow from the heart to the stomach and spleen is relatively unimpaired, the returning veins are squeezed, causing those two organs to become congested with blood.

Impaired blood flow results in shock.

Organs other than the stomach and spleen may also be affected. The portal vein – carrying waste products from the intestines to the liver for detoxification – may become blocked, allowing poisons to accumulate in the blood. Some authorities cite this condition as a major direct cause of death when bloat strikes.

Blood returning to the heart from the digestive organ seeks a new pathway when it finds its normal route shut off. Research has shown that this blood enters the vessels along the vertebral column, swelling and probably damaging them. Despite these efforts by the circulatory system to compensate for the blockage, shock results from the loss of blood pressure.

This circulatory chaos has other consequences: If normal circulation is not restored quickly, portions of the stomach, spleen and other organs may die from lack of oxygenated blood. Subsequent sloughing of the dead tissue can kill the animal, even after surgery has corrected the immediate problem.

Blood clots may form in stopped-up vessels, depleting the supply of chemical factors necessary to coagulate the blood in the event of injury. Also, changes may take place in the pancreas, eventually affecting cellular and subcellular activities. These changes may be on the biochemical level, invisible to the naked eye.

Some of the effects of a bloat attack are obvious. The swollen stomach pushes forward on the diaphragm, making respiration difficult. A bloating dog may literally have to labor for every breath.

What Can Be Done To Treat The Bloating Dog?

Here is a summary of methods suggested by both veterinarians and scientists whom have studied this major health issue:

The first step is to relieve the mounting pressure in the stomach. This not only eases the pain and makes breathing less difficult, but is also important in bringing stability to the shock situation.

In cases of simple dilatation (and sometimes in torsion cases,) a stomach tube can often be passed to allow trapped gas and digestive material to escape. But in cases involving volvulus, the “kink” in the esophagus usually prevents the use of a tube.

If this happens, some veterinarians recommend gastrocentesis – release of the gas through a needle inserted into the stomach from behind the last rib. However, others fear this procedure could damage the spleen, which may have moved into the area where the needle is inserted.

Authorities also disagree as to whether surgery is necessary in all cases involving torsion or volvulus, while others recommend it in every instance.

Surgery may be limited to putting the digestive organs back in proper alignment, but other techniques have been tried with some success. A pyloric myotomy (an operation to weaken the muscle regulating the flow of food from the stomach to the small intestine) is thought to help prevent recurrence by allowing food to pass quickly from the stomach.

Another surgical technique, called gastropexy, involves sewing the stomach to the abdominal wall to prevent excessive movement. If the impaired blood flow during the bloat episode results in tissue death, the spleen and parts of the stomach may have to be removed. In addition, biochemical tests should be run on the pancreas to detect any subtle damage to that organ.

Recommended pre-operative medications include corticosteroids, fluids, and antibiotics to alleviate shock. After surgery, the dog is usually given lactate solution, cortisone, and an antacid containing simethicone, an effective anti-gas agent.

Even though the immediate success rate for surgery is fairly high (about 80% in some clinics), the rate of recurrence is also high. Nearly half the dogs that survive one bout with bloat will be stricken again.

It has been suggested that recurrence is the result of damage to the stomach wall, which prevents that organ from functioning properly again. The time factor may be critically important in averting serious damage to the stomach.

Learning From The Cow

It might be interesting to compare canine bloat to bloat in ruminant animals, which are susceptible to the problem due to the nature of their digestive systems. Because of the economic importance of the cattle industry, bovine bloat has been studied extensively.

The first and largest of the cow’s four stomachs, the rumen, contains bacteria to help break down cellulose. This process releases methane gas, which normally is expelled from the body by belching.

Occasionally, when the animal has fed heavily on young clover or other protein-rich legumes, a tough, tenacious foam forms in the rumen and cannot be eliminated naturally. The rumen can become grossly swollen and the animal may be asphyxiated by the pressure of the lungs.

Scientists now know several things about this type of ruminant bloat. It is apparently caused by soluble proteins and two other chemicals – saponin and pectin – found in young legumes.

Some cows can be more susceptible to bloat than others, for two reasons:

1) Some cattle produce less saliva than others. (Saliva contains an anti-foam agent).

2) Some cattle have certain rumen bacteria that destroy the anti-foam agent in saliva. (A medication is now available that will prevent this kind of bloat in cattle by stopping the production of foam in the rumen.

Cattle fed a grain diet are prone to another kind of bloat known as feedlot bloat. This is caused by rumen bacteria that function normally when the animal is on a varied diet, but produce a slimy foam when the diet is primarily grain. Researchers have sought after medication that will inhibit slime production.

Is There A Connection Between Dog & Cattle?

In cattle, then, bloat seems to result from an interaction of dietary factors and bacterial action. Could the same be true in the dog?

It has been suggested by one scientist who analyzed the stomach contents of dogs which had died from bloat that the swelling was caused by carbon dioxide gas, and that the gas was produced by bacillus and clostridium bacteria. Bacilli and clostridia are probably present in the digestive tracts of most dogs, yet not all suffer from bloat attacks.

Could diet play a role?

Much research is needed to determine what relationship, if any, diet has to bloat. It has been suggested that some modern dog foods containing partially digested material might enhance gas production on the stomach. Control studies are needed to confirm or refute this hypothesis.

If feed is a factor, why is bloat confined mainly to the larger breeds? Do owners encourage engorgement by feeding these dogs one large meal per day, rather than four or five smaller meals?

One theory is that environment could be part of the problem. Today more large dogs are being subjected to apartment living than ever before, and possibly a special diet and exercise program are needed.

It would be useful to know whether bloat is more common today than it was a few decades ago. A comparison of incidence between confined dogs and physically fit dogs (such as racing greyhounds) might also be helpful. Is the environment of the apartment-dwelling dog at all connected to that of the cow confined to the feedlot?

Studies are needed to determine whether bloat might be a purely mechanical problem – a result of anatomical irregularities in large dogs. (It is known that some of the larger breeds are predisposed to certain neurological and orthopedic disorders).

Other possible factors should be examined, including age (two years seems to be the peak danger period); sex (one breeder has claimed all the bloat cases he has seen were in males); familial inheritance and seasonal effects.

Of course, one of the biggest mysteries is how stomach gas is produced in the first place, and why it is not expelled normally. Is the gas produced by the digestion of certain “bloatagenic” foods? Is it formed as a result of bacterial action?

Could it be that most of the gas is merely swallowed air? Clearly, an understanding of this gas production would be an important step toward solving the bloat riddle.

Closing Remarks

Veterinary science is a long way from understanding why dogs such as the Hedl’s Congo suddenly fall victim to this disease, and how it can be prevented or successfully treated.

Answers can only be found through the concerted efforts of veterinary practitioners, research scientists, dog breeders and pet owners. Perhaps when those answers are found, Donna Hedl and thousands of other dog owners can rest easier at night.

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May 15, 2009 | | Reports