Reprinted with permission from the May, 1994 issue of Bloat Notes (News from the Canine Gastric Dilatation-Volvulus Research Program at Purdue University)
Can Bloat Risk for Individual Dogs be Predicted by External Measurements?
Chest conformation measured from radiographs is correlated with breed risk of bloat. Average radiographic measurements for a breed are also correlated very closely with average external chest measurements for that breed. But can conformation measured externally predict the risk of bloat in individual dogs within a breed?
In the case-control study, the chest and abdomen were measured in dogs who had bloat (cases), after the bloated abdomen had been decompressed. These measurements were compared with those from dogs of the same breed and age who had never had bloat (controls).
The results showed that the case-control comparisons of measurements made soon after the bloat episode cannot be used to evaluate conformation as a risk factor for developing bloat. Data from the first 59 pairs indicated that even after decompression, bloat distorted chest and abdominal measurements for up to 30 days. Apparently the disease increased the depth/width ratios enough to create an artificial difference between cases and matched controls. However, if dogs were measured >30 days after decompression, this difference disappeared. Analysis of the effect of elapsed time from the bloat episode to measurement of the case showed clearly that the measurements made soon after decompression were biased by the disease.
The next approach to evaluate depth/width ratios as a risk factor will be to measure dogs of different ages -- perhaps at dog shows -- and follow them over time to find out whether or not they develop bloat.
Are There Diets that Reduce the Risk of Bloat?
Some breeders have told us that they believe that feeding dry dog food (or commercial food of any kind, or soy-based food, etc.) increases the risk of bloat. Others have told us that they believe that one or another specific diet reduces the risk of bloat.
Any or all of these ideas may be correct, but one problem in testing them is the small number of animals available to any one breeder.
One of the objectives of the practitioner/owner case-control study is to evaluate diet as a risk factor. Owners of cases are interviewed regarding the diet fed during the month before the bloat episode. The owners of the matched controls are asked about the diet during the month before the interview. Diet information about the case and control will be compared.
This is no simple task. A quick tabulation (not to be confused with a statistical analysis) of the interview data from the first 26 pairs showed that nearly all of the dogs -- both cases and controls -- were fed dry dog food. This is not surprising, because the dogs weighed > 80 lb on the average, and an earlier study documented that large dogs derive a majority of their calories from dry dog food (LT Glickman et al., 1992, unpublished manuscript).
Among the 26 pairs, the variety of brands of dry dog food and combinations of dry food + snacks + table food was staggering. Obviously, a large number of pairs and sophisticated computer analyses will be needed to detect any dietary factors which might increase the risk of bloat or protect against bloat. The bottom line:
We need as many bloat cases as we can get!
Data Base Study is Published
The first of our bloat studies funded by the Morris Animal Foundation to be published appeared in the veterinary medical literature May 1.
Abstracts of medical records were obtained for 1,934 dogs with bloat (cases) and 3,868 dogs with other diagnoses (controls). The dogs had been admitted to 12 veterinary teaching hospitals from 1980 to 1989, and information from their medical records had been entered into the Veterinary Medical Data Base (VMDB). The case and control groups were compared in order to evaluate factors which might have influenced the risk of developing bloat.
Actual body weight is less important than expected breed weight as a risk factor for bloat.
The overall pattern of risk suggests that body conformation, particularly a narrow and deep thoracic cavity, influences the risk of bloat for specific breeds.
Glickman LT, Glickman NW, Perez CM, Schellenberg DB, Lantz GC: Analysis of risk factors for gastric dilatation and dilatation-volvulus in dogs. J Amer Vet Med Assoc 204(9):1465-1471, 1994.)