Veterinary Services Department, Drs. Foster & Smith, Inc.
What is bloat?
Bloat is the common term for the very serious medical condition known as gastric dilatation and volvulus (GDV). The gastric dilatation is one part of the condition and the volvulus or torsion is the second part. In bloat, due to a number of different and sometimes unknown reasons, the stomach fills up with air and puts pressure on the other organs and diaphragm. Filled with air, the stomach can easily rotate on itself, thus pinching off the blood supply. Once this rotation (volvulus) occurs and the blood supply is cut off, the stomach begins to die and the entire blood supply is disrupted and the animal's condition begins to deteriorate very rapidly. Not all dogs that have a gas buildup and resultant dilatation develop the more serious and life threatening volvulus. However, almost all dogs that have a volvulus develop it as a result of a dilatation. GDV is a very serious and life threatening condition. Understanding the symptoms, prevention and need for prompt treatment will help reduce the risk of mortality if your dog develops this problem.
What breeds are more susceptible?
There is a definite link between the likelihood of occurrence of GDVand the breed and build of the dog. GDV is much more likely to occur in large, deep-chested breeds. The problem can occur in small dogs but only rarely. The University of Purdue recently conducted a study of hundreds of dogs that had developed GDV and they calculated a ratio of likelihood of a particular breed developing the problem as compared to a mixed breed dog. For example, using the GDV risk ratio a Great Dane is 41.4 times more likely to develop GDV than a mixed breed dog.
| Breed | GDV Risk Ratio | Risk Rank |
|---|---|---|
|
Great Dane |
41.4 |
1 |
|
Saint Bernard |
21.8 |
2 |
|
Weimaraner |
19.3 |
3 |
|
Irish Setter |
14.2 |
4 |
|
Gordon Setter |
12.3 |
5 |
|
Standard Poodle |
8.8 |
6 |
|
Basset Hound |
5.9 |
7 |
|
Doberman Pinscher |
5.5 |
8 |
|
Old English Sheepdog |
4.8 |
9 |
|
German Shorthaired Pointer |
4.6 |
10 |
|
Newfoundland |
4.4 |
11 |
|
German Shepherd |
4.2 |
12 |
|
Airedale Terrier |
4.1 |
13 |
|
Alaskan Malamute |
4.1 |
14 |
|
Chesapeake Bay Retriever |
3.7 |
15 |
|
Boxer |
3.7 |
16 |
|
Collie |
2.8 |
17 |
|
Labrador Retriever |
2 |
18 |
|
English Springer Spaniel |
2 |
19 |
|
Samoyed |
1.6 |
20 |
|
Dachshund |
1.6 |
21 |
|
Golden Retriever |
1.2 |
22 |
|
Rottweiler |
1.1 |
23 |
|
Mixed |
1.0 |
24 |
|
Miniature Poodle |
0.3 |
25 |
Is there a genetic link?
In addition to breed predilection, there appears to be a genetic link to this disease. The incidence is closely correlated to the depth and width of the dog's chest. Several different genes from the parents determine these traits. If both parents have particularly deep chests then it is highly likely that there offspring will have a deep chest and the resulting problems that may go with it. This is why in particular breeds we see a higher incidence in certain lines, most likely because of that line's particular chest conformation.
What causes gastric dilatation and volvulus?
There is not one particular activity that leads to the development of GDV. It appears that it occurs as a combination of events. Studies of the stomach gas that occurs in dilatation have shown that it is similar to the composition of normal room air suggesting that the dilatation occurs as a result of swallowing air. All dogs, and people for that matter, swallow air but normally we eructate (burp) and release this air and it's not a problem. For some reason that scientist have not yet determined these dogs that develop bloat do not release this swallowed gas. There is currently several studies looking into what happens physiologically in these dogs that develop GDV. Through previous studies there are several different factors that increase the likelihood of developing the disease. They are: being a male, being underweight, eating only one meal a day, eating at a faster rate, and being a fearful or nervous dog.
What are the symptoms?
The symptoms include restlessness, pacing, rapid onset of abdominal distension, rapid shallow breathing and nonproductive vomiting and retching. Profuse salivation may indicate severe pain. If the dog's condition continues to deteriorate, especially if volvulus has occurred, the dog may go into shock and become pale, have a weak pulse and a rapid heart rate. A dog with gastric dilatation without volvulus can show all of these symptoms but the more severe symptoms are likely to occur in dogs with both dilatation and volvulus.
How is gastric dilatation and volvulus treated?
Even with treatment, it is estimated that at least 35% of the dogs with gastric dilatation and volvulus die. When the dog is presented to the hospital its condition is assessed and depending on the severity of the condition one of a number of different treatment protocols are instituted. Usually intravenous catheters are placed and fluids are administered. Then the stomach is decompressed either by passing a stomach tube or inserting a large needle into the stomach and releasing the gas. After the animal is stabilized x-rays are taken to determine whether or not a volvulus is present. If a volvulus is present then surgery is performed to correct the volvulus. The stomach is permanently stitched to the abdominal wall to prevent reoccurrence and then the animal is monitored and treated, as needed, based upon the symptoms. Animals that develop just dilatation are at a much greater risk of developing dilatation and volvulus in the future and many times the surgery to attach the stomach permanently is performed to prevent this from happening. Because this surgery is difficult and invariably happens at night, many veterinarians will decompress the stomach and treat the patient supportively and refer them to a specialty practice or wait until morning when adequate help is available to assist with the surgery.
Dogs with gastric dilatation and volvulus can develop severe complications including bleeding disorders, heart arrhythmias, and peritonitis.
How is gastric dilatation and volvulus prevented?
Despite adopting all of the recommendations listed below a dog may still develop GDV. Because of the genetic link involved with this disease prospective pet owners should question if there is a history of GDV in the lineage of any puppy that is from a breed listed as high risk. In addition, the following recommendations should be followed:
Summary
Bloat is a life threatening condition that most commonly affects large-breed, deep-chested dogs over two years of age. Owners of susceptible breeds should be knowledgeable about the symptoms of the disease since early and prompt treatment can greatly improve the outcome. By following the preventative measures recommended, pet owners can further reduce the likelihood of their pet developing this devastating problem.
References
Bojrab. Current Techniques in Small Animal Surgery. Williams & Wilkins. Baltimore, MD; 1990.
Veterinary Internal Medicine, Ettinger: Epidemiology of gastric dilatation-volvulus in dogs. Glickman.
