Bloat: Identifying Risk Factors and Preventive Measures
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Although much research remains to be done to understand bloat (Gastric Dilatation - Volvulus) in dogs, significant advances have been made. Current scientific research does indicate that bloat is a dietary disease. Although specific causes of bloat are not known, identifying risk factors and high-risk dogs will help dog owners adopt preventive measures.
Gastric dilatation-volvulus (GDV), often called bloat or gastric torsion, is a complex disorder which usually occurs as a lifethreatening emergency. Bloat is characterized by expansion of the stomach with gas or frothy material (dilatation). The stomach will not empty normally. In the stomach of a dilated dog it is difficult for food to advance into the intestines, nor will food pass in the other direction as vomit.
Dilatation can be followed by a rotation of the stomach (volvulus or torsion), which effectively closes both the entry to and exit from the stomach, so that relief of the distended state is not possible. This rotation compresses one of the major veins carrying blood to the heart, severely depressing normal blood circulation. This condition can rapidly lead to shock and death. Bloat can be sudden and devastating in an apparently healthy dog. Hereditary predisposition has been suggested in certain instances. However, conclusive documentation is difficult to obtain because of the sporadic nature of GDV.
New Studies Focus On Risk Factors
Recent studies provide new insight into risk factors associated with bloat. Analysis of Risk Factors for Gastric Dilatation and Dilatation - Volvulus in Dogs by Dr. Lawrence Glickman, et. al., the Department of V eterinary Clinical Science at Purdue U ni versity, was published in the May 1, 1994 issue of The Journal of the American Veterinary Association.
This study is based on bloat cases from 12 veterinary hospitals. Abstracts of medical records were obtained for 1,934 dogs with bloat (cases) and 3,868 dogs (controls) with other diagnoses. Only initial rather than reoccurring bloat cases were included in the study. The case and control groups were compared in order to evaluate factors which might have influenced the risk of developing bloat.
The Purdue study defined risk factors as any aspect of life style or behavior, environmental exposure or inherited characteristic that is associated with the occurrence of a disease. That is, any characteristic observed more frequently in the group with bloat than the control group.
Risk Factors Identified
The Purdue study identified these factors which influence the risk of developing bloat:
Increasing age was a significant risk factor. Dogs older than seven years were at least twice as likely to have bloat as dogs two to four years of age.
Actual body weight was found to be less important than expected body weight based on breed standards as a risk factor for bloat. There are many health care reasons to prevent obesity in dogs such as cardiovascular problems and strain on muscles and joints. However, as a strategy to help prevent bloat, attempts to reduce a dog's body weight by caloric restriction would probably have little effect.
Purebred dogs were more likely to develop bloat than were mixed breed dogs.
No significant association of bloat with sex orneuterlspay status was found.
The six more common breeds with the highest risk of bloat were Great Dane, Weimaraner, Saint Bernard, Gordon Setter, Irish Setter and Standard Poodle.
Less common breeds with a high risk included the Irish Wolfhound, Borzoi, Bloodhound, Mastiff, Akita and Bull Mastiff.
Body conformation, particularly a narrow and deep thoracic cavity, increased the risk of bloat for specific breeds.
The frequency of bloat among all dogs admitted to the different hospitals in the Purdue study ranged from 2.9 to 6.8 per 1,000 dogs.
A total of 28.6 percent of the dogs with gastric dilatation and 33.3 percent of those with dilatation and volvulus died in the hospital.
Study of Feeding Practices, Behavior Provides New Insight
Another study conducted at the Virginia-Maryland Regional College of Veterinary Medicine by Dr. Neal Bataller involved over 700 dogs presented at nine veterinary hospitals. Of these dogs, 244 were bloat patients. The other dogs were admitted for other reasons and provided the control group for the study. This study looked at diet and behavior and their relationship to bloat and presents new observations about feeding and water management. A number of different diets and feeding strategies were represented in the study. Based on this study, Dr. Bataller believes that diet tends to be overemphasized as a cause of bloat. Preliminary results identified several risk factors.
In the study, dogs fed once a day were at no greater risk than those on any other feeding frequency. However, Dr. Bataller cautions that this is preliminary information. Additional studies are needed to verify it.
Nervous Dogs at Risk
Dr. Bataller's findings suggest that the more nervous the dog, the more at risk. Dogs in the study were defined by their owners as calm, normal, nervous or very nervous. Normal dogs were almost twice as likely to develop bloat as compared to calm dogs. Very nervous dogs were 12 times more likely to be at risk.
Based on behavior reported by owners, the dogs with bloat have behavior patterns that showed the dogs ingesting large amounts of air.
Dogs in the study that gulped water were twice as likely to get bloat as dogs that lap water normally. Many owners of dogs with bloat also reported that their dogs panted or belched excessively before bloating.
Other findings in the study suggest that many kinds of stressful events are often associated with the onset of bloat such as a trip, the excitement of a picnic, a thunderstorm, and kenneling. While it is virtually impossible for a dog owner to prepare a dog for all stressful situations, helping a dog ease into such situations is desirable. For example, if a dog is to be kenneled, accustom the dog to spending more hours in his dog crate and having limited access to exercise prior to being boarded.