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The Mystery of Bloat

Mattie, delayed by traffic, felt guilty about feeding her Great Dane Rufus later than usual. But Rufus, as always, forgave her and gulped down his meal as soon as the bowl hit the floor. An hour later though, Rufus's normally jovial mood changed. He anxiously paced the floor, whining off and on. He tried to vomit, but nothing came up. Frightened by her dog's obvious distress, Mattie dialed her veterinarian's emergency number. After Mattie described the situation, the veterinarian asked to see Rufus immediately.

At the clinic, the veterinarian examined and radiographed (X-rayed) Rufus's abdomen. The film revealed a gas filled, dilated stomach twisted into an abnormal position. The doctor commended Mattie for her astute observation and decisive action and immediately began treating Rufus for bloat.

Gastric dilation-volvulus (GDV), commonly called "bloat", is a potentially fatal condition in which a dog's stomach distends (dilation) with, gas, food, and fluid and rotates or twists (volvulus). The twisting action blocks both the entrance to the stomach via the esophagus ("foot tube") and the exit from the stomach via the pylorus.

Distention and twisting can occur independently of one another but when both occur, rapid veterinary intervention is critical. The "one-two punch" of distention and twisting generally results in shock (insufficient blood circulation), leading to multiple organ failure and death within a matter of hours. "Most GDV fatalities result from the cascade effect of shock," says Dr. Janet Welch, chief surgical resident at Tufts University School of Veterinary Medicine.

With GDV, every minute can affect a dog's chances of survival. But the signs of bloat are not always obvious, and even with appropriate and timely medical care, some dogs don't survive. (Experts estimate a 25 to 50 percent mortality rate for dogs diagnosed with GDV). If you understand how dogs with GDV typically behave, however (see "What You Should Know About GDV"), you'll have a better chance of catching this potentially fatal condition in time.

Although no one knows for sure what causes GDV, studies indicate that older purebred dogs - especially larger, deep-chested breeds such as Great Danes, Irish Setters, and Saint Bernards - show a disproportionately high incidence of GDV. However, body type may be as significant a risk factor as size. (Basset Hounds and Airedale Terriers, both midsized breeds, consistently appear on lists of breeds most susceptible to GDV.) Preliminary results from bloat studies at Purdue University's School of Veterinary Medicine indicate that dogs with a higher chest depth-to-width ratio may be a greater risk of developing bloat. "With deep, narrow chests, there's a greater opportunity for the ligaments that support the stomach to stretch, especially when the stomach is full," explains Dr. Larry Glickman, professor of epidemiology at Purdue. A "loose" stomach, the Purdue researchers hypothesize, may be more prone to twisting.

GDV usually occurs within a few hours after a dog eats a meal. Yet no single food type, ingredient, or feeding method has been shown to cause GDV. In fact, GDV seems to be "multifactorial in nature", says Dr. Lisa Freeman, clinical instructor at Tufts University School of Medicine. "We know some of the predisposing factors, but we don't know exactly what causes GDV". Thus, taking food-related precautions (see "What You Should Know About GDV") makes sense but will not necessarily prevent GDV.

As GDV progresses, the twisting motion collapses and sometimes tears the blood vessels supplying the stomach, causing gradual death (necrosis) of the stomach tissue. To make matters worse, the twisting constricts the vessels supplying blood to other abdominal organs (such as the spleen and pancreas) and restricts blood flow back to the heart. The reduction in blood flow returning to the heart diminishes overall cardiac output, curtailing blood supply to the entire body.

Circulatory stagnation also increases the probability that bacteria-laden intestinal contents will leak through the usually impermeable intestinal wall into the bloodstream. If this happens, a blood infection (septicemia) could result, contributing to shock. An even more severe condition, septic peritonitis, sets in if bacteria and their toxic byproducts enter the abdominal cavity through holes in the intestine. Septic peritonitis causes an estimated 33 to 50 percent of GDV fatalities.

A veterinarian may be able to confirm dilation simply by examining the patient. But to determine whether there is dilation and volvulus, your veterinarian will probably take an abdominal X-ray. An X-ray of a dog with GDV reveals a swollen stomach that has a "double bubble" appearance.

Once a veterinarian confirms GDV, the patient must undergo surgery to empty, reposition, and secure the stomach. But first, the veterinarian administers intravenous fluids to the dog to counteract shock. In addition, the veterinarian tries to relieve the gastric pressure (caused by accumulated gas and fluids) by inserting a lubricated, flexible tube down the esophagus and into the stomach. If the twist blocks access to the stomach, the veterinarian may insert a needle through the dog's skin (behind its last rib) into the stomach to help release the gas buildup (trocarization). (To tolerate these procedures, many dogs require sedation).

After stabilizing the dog's condition, the surgeon - who (depending on the situation) may or may not be the dog's regular veterinarian - anesthetizes the patient in preparation for surgery, carefully regulating the level of anesthesia.

Once inside the gog's abdomen, the surgeon may discover that GDV has so irreversibly damaged the stomach or other abdomiinal organs that the dog could never lead a normal life. The surgeon may recommend euthanizing the animal at that point to prevent further pain and suffering.

But if the prospects for recovery are more favorable, the surgeon proceeds - removing dead stomach tissue; suruting the remaining parts of the stomach together; and restoring the stomach to its normal, untwisted position. If GDV has also damaged the spleen, the surgeon will remove all or part of it. (Spleen free dogs can live perfectly normal lives). The surgeon then peforms one of several types of stomach attachments (gastropexies) to reduce the risk of future volvulus (see below Bloat: Surgical Options).

After surgery, a patient still faces many days of hospitalization with close monitoring. Although some dogs develop bloat-related abnormal heart rythms (arrhythmias) before surgery, these irregularities may also crop up duriing the first 36 hours after surgery. Therefore, the veterinarian uses an electrocardiogram (EKG) to monitor a recovering dog's heart and may administer antiarrhythmia drugs if necessary.

When the stomach untwists, toxins that built up in the thssues suddenly reenter the bloodstream and flow through the dog's body, points out Dr. Mary Labato, clinical assistant professor at Tufts University School of Veterinary Medicine. So a recovering dog may require further intensive treatment to combat the effects of these toxins.

A recuperating dog can usually begin eating 2 or 3 days following surgery. Professionals recommend small, frequent meals and a bland diet such as boiled chicken and rice or a special prescription food. (Dogs that have no appetite or that suffered extensive stomach damage may require intravenous feedins.) If all goes well, a dog can usually return to its normal diet 2 to 3 weeks after surgery.

Because much about GDV remains unkknown, an owner can do everything by the book and still not escape the sometimes tragic consequences of GDV. Because there are no sure-fire preventive measures, your best bet is to follow your veterinarian's advice and stay current with the latest discoveries about this mysterious ailment.

To help prevent bloat from recurring, veterinary surgeons attache the decomporessed and untwisted stomach to nearby structures (gastropexy). Studies indicate that gastropexy drastically reduces the recurrence rate of GDV.

In the tubal gastropexy, a surgeon inserts a tube through the skin and abdominal wall into the stomach. Then, using the tube, the surgeon pulls the stomach toward the abdominal wall and sutures the stomach to the muscles of the wall. (The tube remains in place for 7 to 10 days and can facilitate feeding). In the simple gastropexy, a surgeon sutures the stomach directly to the abdominal wall. Some surgeons perform circumcostal gastropexies by attaching a flap of the stomach to the dog's last rib.

The most popular today is the belt-loop gastropexy, in which the surgeon attaches a portion of the stomach to a belt loop flap created in the abdominal wall. This relatively simple procedure creates a secure attachment.

A new technique called the surgical staple allows the surgeon to staple together a layer of the abdominal wall and stomach. Thie procedure is faster than the belt-loop and circumcostal procedures and stronger than a simple gastropexy. Most important, a single vererinarian can perform the surgical staple procedure without assistance - a potential lifesaver in an after-hours emergency.

Occasionally, ownere who have lost a pert to GDV (or own a breed predisposed to GDV) request a preventative gastropexy. Your veterinarian may recommend this preventative surgery if your dog suffers repeated stomach dilation, to lessen its chances of developing volvulus later on.

If a dog with GDV could talk, it would complain of abdominal pain, nausea, and weakness. But alas, our canine friends can't verbalize this information, so owners have to look for outward signs. If your dog exhibits one or more of the following conditions or behaviours - especially within a few hours of eating - call your veterinarian without delay. (Always have handy your veterinarian's phone number and that of the nearest emergency animal hospital.)