Bloat

WHAT IT ALL MEANS

Canine bloat, or gastric dilatation-volvulus (GDV), is the number-one cause of death for several breeds of dog. If this painful disorder is not treated within one to two hours, it is life-threatening.

In the bloated stomach, gas and/or food stretches the stomach many times its normal size, causing tremendous abdominal pain. For reasons we do not fully understand, this grossly distended stomach has a tendency to rotate, thus twisting off not only its own blood supply but the only exit routes for the gas inside. Not only is this condition extremely painful but it is also rapidly life-threatening.

Twenty-five percent of bloat cases are caused by gastric dilation. The stomach fills with gas. The increased pressure compresses both ends of the stomach, preventing the gas from escaping. But most cases--75 percent--are due to gastric volvulus, where the stomach actually twists, crimping and cutting off the inflow and outflow from the stomach. When the stomach gases cannot get out, they expand.

HAS MY DOG BLOATED?!!! WHAT TO LOOK FOR!

Affected dogs drool saliva because they cannot swallow. Also, they cannot belch or vomit, which would help relieve the mounting pressure from the stomach gases. The pressure causes the abdomen to become distended. When tapped, the abdomen can sound like a drum.

The dog may have an obviously distended stomach especially near the ribs but this is not always evident depending on the dog's body configuration.

If any of this is seen or even SUSPECTED , rush your dog to the veterinarian IMMEDIATELY!

WHAT HAS TO BE DONE

There are several steps to saving a bloated dogs life. Part of the problem is that all steps should be done at the same time and as quickly as possible.

FIRST:DECOMPRESSION OF THE STOMACH

The huge stomach is by now pressing on the major blood vessels carrying blood back to the heart. This stops normal circulation and sends the dog into shock. Making matters worse, the stomach tissue is dying because it is stretched too tightly to allow blood circulation through it. There can be no recovery until the stomach is untwisted and the gas released. A stomach tube and stomach pump are generally used for this but sometime surgery is needed to achieve stomach decompression.

WHILE GIVING RAPID IV FLUIDS TO PREVENT SHOCK

Intravenous catheters are placed and life-giving fluid solutions are rushed in to replace the blood that cannot get past the bloated stomach to return to the heart. The intense pain associated with this disease causes the heart rate to race at such a high rate that heart failure will result. medication to resolve the pain is needed if the patient’s heart rate is to slow down. Medication for shock, antibiotics and electrolytes are all vital in stabilizing the patient.

WHILE ASSESSING AND STABILIZING THE HEART RHYTHM

There is a special very dangerous rhythm problem, called a "premature ventricular contraction" or "pvc," associated with bloat and it must be ruled out. If it is present, intravenous medications are needed to stabilize the rhythm. Since this rhythm problem may not be evident until even the next day continual EKG monitoring may be necessary. Disturbed heart rhythm already present at the beginning of treatment is associated with a 38% mortality rate.

Getting the bloated dog's stomach decompressed and reversing the shock is an adventure in itself but the work is not yet half finished.

SURGERY

All bloated dogs, once stable, should have surgery. Without surgery, the damage done inside cannot be assessed or repaired plus bloat may recur at any point, even within the next few hours and the above adventure must be repeated. Surgery, called gastrpexy, allows the stomach to be tacked into normal position so that it may never again twist. Without gastropexy, the recurrence rate of bloat may be as high as 75%!

Assessment of the internal damage is also very important to recovery. If there is a section of dying tissue on the stomach wall, this must be discovered and removed or the dog will die despite the heroics described above. Also, the spleen, which is located adjacent to the stomach may twist with the stomach. The spleen may require removal, too.

If the tissue damage is so bad that part of the stomach must be removed, the mortality rate jumps to 28 - 38%.

If the tissue damage is so bad that the spleen must be removed, the mortality rate is 32 - 38%.

After the expense and effort of the stomach decompression, it is tempting to forgo the further expense of surgery. However, consider that the next time your dog bloats, you may not be there to catch it in time and, according the study described below, without surgery there is a 24% mortality rate and a 76% chance of re-bloating at some point. The best choice is to finish the treatment that has been started and have the abdomen explored. If the stomach can be surgically tacked into place, recurrence rate drops to 6%.

In breeds that are at high risk, many experts recommend having a preventative gastropexy performed instead of waiting for an episode of bloat. In pet dogs, this surgery is usually performed at the time of neutering. In the December 1, 2002, Journal of the American Veterinary Medical Association, researchers described a new laparoscopic gastropexy technique. This technique requires only a small incision on the side of the abdomen.

RISK FACTORS

Classically, this condition affects dog breeds which are said to be "deep chested," meaning the length of their chest from backbone to sternum is relatively long while the chest width from right to left is narrow. Examples of deep chested breeds would be the Great Dane, Greyhound, and the setter breeds. Still, any dog can bloat, even dachshunds and chihuahuas.

Historically,the dog had eaten a large meal, however we usually do not know why a given dog bloats on an individual basis. No specific diet or dietary ingredient has been proven to be associated with bloat other than a dry food only diet that is served as one large meal. Some factors found to increase and decrease the risk of bloat are listed below:

The breed with the highest average lifetime likelihood of a bloat episode is the Great Dane, at 42.4%. Other breeds at higher-than average risk include the Bloodhound, Irish Wolfhound, Irish Setter, Akita, standard Poodle, German Shepherd Dog, and Boxer. Other deep-chested breeds and deep-chested mixed-breed dogs are also at higher risk.

Dr. Larry Glickman, an epidemiologist at the Purdue University School of Veterinary Medicine, conducted a controlled study on canine bloat, beginning in 1994. He followed 1,914 dogs who did not have a prior history of bloat. Eleven large and giant breeds were represented in the study.

Several risk factors were identified. The dogs with the greatest risk of developing bloat have chests that are deep and narrow. This can be evaluated by measuring the depth and the width of the chest. Then the depth is divided by the width. The depth-to-width ratio reflects the amount of room there is for stomach movement in the abdomen, behind the ribcage. The higher the result, the more room there is for movement. Dogs with more room have a greater risk of developing bloat.

Lean dogs were found to be at higher risk than overweight dogs. It is hypothesized that this is because fat takes up space in the abdomen. The lack of fat in the abdomen of a lean dog creates a basic situation similar to that of a dog with a deep and narrow chest: A lean dog has much more room in the abdomen for the stomach to move around than a fat dog. This does not mean, of course, that overweight dogs are generally healthier than lean dogs.

Risk is also higher for older dogs. For large breeds, the risk of developing bloat goes up 20 percent each year after the age of 5. For giant breeds, it goes up 20 percent each year after the age of 3. First degree relatives of dogs that have had bloat have a 63 percent greater risk of developing bloat themselves. Dogs that eat quickly have a 15 percent higher risk of developing bloat. This may be related to increased swallowing of air.

One traditional preventative has been to raise the height of food and water bowls, but this was found to actually increase risk by 110 percent. This correlation of risk was verifiable; the dogs of the breeders in this study did not have close relatives that had experienced bloat.

The study also found that fearful, nervous, or aggressive dogs had a much higher incidence of bloat than did dogs perceived by their owners as having happy temperaments. Stress can also be a precipitating factor, and many dogs bloat after recent kenneling, or a recent long car ride. A slightly higher percentage of males than females developed bloat.

Several diet-related factors were associated with a higher incidence of bloat. These include feeding only dry food, or feeding a single large daily meal. Dogs fed dry foods containing fat among the first four ingredients had a 170 percent higher risk for developing bloat. Dogs fed dry foods containing citric acid and were moistened prior to feeding had a 320 percent higher risk for developing bloat.

Conversely, feeding a dry food containing a rendered meat-and-bone meal decreased risk by 53 percent in comparison with the overall risk for the dogs in the study. Mixing table food or canned food into dry food also decreased the risk of bloat.

During the past 30 years there has been a 1,500 percent increase in the incidence of bloat, and this has coincided with the increased feeding of dry dog foods. There is a much lower incidence of bloat in susceptible breeds in Australia and New Zealand. Feeding practices in these countries have been found to be less dependent on dry foods.

As for feeding one large meal a day, this can weigh down the stomach and stretch the hepatogastric ligament, which usually maintains the stomach's normal position in the abdomen. Dogs that have bloated were found to have a much longer hepatogastric ligament; it is thought that this is due to chronic stretching. This could also explain why bloat risk increases with age.

Several popular theories regarding bloat were not substantiated during the study. There was no correlation of bloat risk to exercise before or after eating, as most dogs bloated in the middle of the night with an empty, gas-filled stomach. There was also no correlation to vaccinations, to the brand of dog food consumed, or to the timing or volume of water intake before or after eating.

From the research performed to date, we can list several factors that, added together, can characterize the typical dog that develops bloat: a deep and narrow chest; leanness; a relative that has had a bloat episode; eating quickly; a dry-food diet; a single, large daily meal; stress; and a fearful, nervous, or aggressive temperament.

FACTORS INCREASING BLOAT RISK

• Feeding only one meal a day
  
• Feeding only dry food
  
• Having closely related family members with a history of bloat
  
• Eating rapidly
  
• Being thin or underweight
• Fearful or anxious temperament
  
• History of aggression towards people or other dogs
  
• Male dogs are more likely to bloat than females
  
• Older dogs (7 - 12 years) were the highest risk group
• Family with history of bloat
  

FACTORS DECREASING BLOAT RISK

• Inclusion of canned dog food in the diet
  
• Inclusion of table scraps in the diet
  
• Happy or easy-going temperament
  
• Eating 2 or more meals per day

STUDY:

In 1993, a statistical study involving 134 dogs with gastric dilatation and volvulus was conducted by the School of Veterinary Medicine in Hanover, Germany.

Out of 134 dogs that came into the hospital with this condition:

• 10% died or were euthanized prior to surgery (factors involved included expense of treatment, severity/advancement of disease etc.)
  
• 33 dogs were treated with decompression and no surgery. Of these dogs, 8 (24%) died or were euthanized within the next 48 hours due to poor response to treatment. (Six of these 8 had actually re-bloated).
  
• Of the dogs that did not have surgical treatment but did survive to go home, 76% had another episode of gastric dilatation and volvulus eventually.
  
• 88 dogs were treated with both decompression and surgery. Of these dogs, 10% (9 dogs) died in surgery, 18% (16 dogs) died in the week after surgery, 71.5% (63 dogs) went home in good condition. Of the dogs that went home in good condition, 6% (4 dogs) had a second episode of bloat later in life.
  
• In this study 66.4% of the bloated dogs were male and 33.6% were female. Most dogs were between ages 7 and 12 years old. The German Shepherd dog and the Boxer appeared to have a greater risk for bloating than did other breeds.

Data for this post was acquired from the following sources. Much of this post is a word by word reprint of these two articles.

Meyer-Lindenberg A., Harder A., Fehr M., Luerssen D., Brunnberg L. Treatment of gastric dilatation-volvulus and a rapid method for prevention of relapse in dogs: 134 cases (1988-1991) Journal of the AVMA, Vol 23, No 9, Nov 1 1993, 1301-1307.

Bell Jerald, DVM ,Tufts University School of Veterinary Medicine, "Risk Factors for Canine Bloat"