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Bloat Notes

Among the various sources which we have for articles appearing in The Reporter are other newsletters. We are fortunate enough to now exchange newsletters with: Rott n Chatter (obviously a Rottweiler newsletter) which is similar to The Reporter in supplying information, but with a lighter side. Also exchanging with us is the Double Helix Net- work News put out by C. A. Sharp who was head of the Australian Shepherd Club of America (ASCA - non-AKC Aussies) Genetics Committee until it was disbanded. This features a wealth of genetic articles and information, many of which may be applicable to our big guys.

One of our readers, Deirdre Green/Buffalo, NY, led us to the newsletter featured in the next article -- Bloat Notes. This publication is "News from the Canine Gastric Dilatation- Volvulus Research Program" at the School of Veterinary Medicine, Purdue University, W. Lafayette, IN. This newsletter should be of great interest to our breed (as well as other high- risk breeds) and we will be receiving a subscription. Unfortunately only two issues have been printed so far -- May, 1993 and December, 1993. They did say that the first 1994 issue was in process.

STUDIES OF RISK FACTORS FOR BLOAT IN DOGS: PURPOSE AND PROGRESS

A research program of risk factors for bloat (canine gastric dilatation-volvulus; CGDV) is underway at Purdue University School of Veterinary Medicine. The long-term objec- tives of this research are to:

  1. Identify the multiple host and environmental factors that predispose dogs to bloat.
  2. Develop, implement, and evaluate preventive strategies and therapeutic ap- proaches for bloat.
  3. Educate veterinarians and dog owners about prevention and treatment of bloat.
  4. Coordinate research efforts on bloat and act as a clearing house for information regarding this disease.

The current studies of bloat, which are funded by the Morris Animal Foundation and began in September 1991, are as follows:

Retrospective Record Review and Host Factor Analysis Using the Veterinary Medical Data Base (VMDB).
Objective: To describe the frequency of CGDV in a broad-based hospital population during 1980-1989 and to generate hypotheses regarding risk factors for its occurrence.
Practitioner/Owner Case-Control Study
Objective: To test specific hypotheses regarding risk factors for CGDV.
Practitioner/Owner Prospective Survival Study
Objective: To evaluate prognostic factors for recurrence and postoperative mortality in CGDV (up to 1 year follow-up).

Data have been collected and analyzed for the retrospective study of VMDB records, and papers are being prepared for publication (see Highlights story that follows).

In the practitioner/owner case-control study, veterinary practitioners provide clinical data and measurements of dogs with bloat (cases) and dogs without bloat (controls) of the same breed and age ( 2 years). Each dog's owner is interviewed about the dog's diet, exercise patterns, temperament, and other factors, as well as, for cases, the dog's activities shortly before the bloat episode. This study is progressing well, but we need more bloat cases.

The follow-up study is also progressing, but since the cases come from the case-control study, more cases are needed as soon as possible so follow-up can begin.

Their current study features 24 breeds at risk for bloat and the Mastiff is not listed. When asked why, the reply was because they did not receive any case studies on Mastiffs. If you have had a bloat case, or know of someone who has had a case, please have the attending veterinarian contact Purdue University and volunteer the information. We need to get our guys in this study to make it pertinent to our breed. Contact Larry Glickman (317) 494-7543 or Diana Schellenberg (317) 494-1446. If you wish to receive the Bloat Notes newsletter directly, contact Diana Schellenberg at the above number. It is free of charge.

HIGHLIGHTS FROM THE DATABASE STUDY (RETROSPECTIVE VMDB STUDY)

With funding from the Morris Animal Foundation, the research team recently completed a study of risk factors for developing bloat, using information from 12 veterinary teaching hospitals as recorded in the Veterinary Medical Data Base (VMDB) in 1980-1989. Cases included 1934 dogs with bloat; controls were 3868 dogs with other diagnoses randomly selected from the same hospitals.

How many dogs get bloat each year? We know of no surveys of overall incidence, but in the VMDB study the annual hospital incidence (no. cases/total no. admissions) ranged from 2.8 to 6.6 per 1,000 admissions.

How many dogs with bloat die? Published case series indicate that in recent years, improved surgical techniques and perioperative medical management have improved post- treatment mortality rates. However, some dogs still die of intra- or postoperative complications, and others die before surgery or are euthanized. In our VMDB study, 30.9% of the 1934 dogs with bloat died, including dogs that had surgery and medical treatment and also dogs that died before surgery or were euthanized.

In a retrospective study of 160 dogs seen in the Netherlands, mortality rates decreased significantly from 63% in 1977-1982 to 29% in 1984-1990 (Van Sluijs FJ: Tidschr Diergeneeskd 116(3): 112-121, 1991). In our VMDB study, the percentage of deaths for bloat was only slightly better during the period 1985-1989 than during the period 1980-1984.

The VMDB study did not allow analysis of survival after specific treatments, but this is an important feature of our case-control study. The VMDB study also could not evaluate long-term survival or recurrence rates, but this is an important aspect of our ongoing follow-up study.

The VMDB study showed males and females to be equally at risk of bloat, but neutering appeared to have a small but statistically significant protective effect in both sexes - - an unexpected finding. (Do you have any theories to explain it??)

As would be expected from the literature, older dogs and heavier dogs were at greater risk of developing bloat. However, the size of the breed (based on ideal body weight) had more effect on risk than the dog's actual weight. This suggests that weight reduction may not reduce the risk of developing bloat in large-breed dogs. Our case-control study, in which dogs are matched by breed, will allow more detailed analysis of weight as a risk factor.

Purebred dogs were 3 times as likely to develop bloat as mixed-breeds. Differences in risk among specific pure breeds were striking. Table 1 (page 9) lists the risk ranking for each of 24 breeds compared with the risk for all 5802 dogs combined (4547 purebred dogs and 1255 mixed-breeds.

The overall pattern of risk suggests that body conformation, particularly a deep chest, may be an important determinant of susceptibility to bloat. Body measurements being done in the case-control study will allow the first systematic comparison of dogs with bloat and other dogs of the same breed in regard to this factor.

A paper reporting the analysis of risk factors for developing bloat has been submitted to the Journal of the American Veterinary Medical Association. VMDB data on factors influencing short-term survival are being analyzed.

RESEARCH PROPOSAL TO MORRIS ANIMAL FOUNDATION

The Purdue bloat research group sent a research proposal to the Morris Animal Foundation in March. The proposed studies, if funded, will run from September 1, 1993 to August 31, 1995, and are as follows:

Practitioner/Owner Case-Control Study
Objective: Expand the ongoing case-control study of factors which predispose a dog to bloat and of precipitating factors.
Practitioner/Owner Prospective Survival Study
Objective: Expand and extend the ongoing follow-up study of dogs with bloat to identify prognostic factors for survival and recurrence.
Radiographic Morphometry Study
Objective: Use radiographs to assess chest conformation as a risk factor for bloat.
Inheritance Patterns of CGDV Risk
Objective: Characterize the role of inheritance in the risk of bloat.
The principal investigator is Dr. Larry Glickman, Professor of Epidemiology and Head, Depart- ment of Veterinary Pathobiology; co-investigators are Dr. Gary C. Lantz, Professor of Surgery, and Dr. William R. Widmer, Associate Professor of Diagnostic Imaging, both in the Department of Veterinary Clinical Sciences.

Why is a dog's breed such an important risk factor for bloat? Veterinarians have

TABLE 1:
BLOAT RISK RANKING FOR 24 PURE BREEDS, COMPARED WITH RISK FOR ALL DOGS COMBINED*

Breed                     | No.Cases | No.Controls | Risk Rank
--------------------------------------------------------------
Great Dane *              | 299      |  37         |  1
St. Bernard *             |  81      |  19         |  2
Weimaraner *              |  49      |  13         |  3
Irish Setter *            | 180      |  65         |  4
Gordon Setter *           |  24      |  10         |  5
Standard Poodle           |  57      |  33         |  6
Basset Hound *            |  39      |  34         |  7
Doberman Pinscher *       | 139      | 130         |  8
Old English Sheepdog *    |  27      |  29         |  9
German Short-hair Pointer |  25      |  28         | 10
Newfoundland              |  13      |  15         | 11
Airedale Terrier          |  12      |  15         | 12
German Shepherd *         | 202      | 246         | 13
Alaskan Malamute          |  23      |  29         | 14
Chesapeake Bay Retriever  |  10      |  14         | 15
Boxer                     |  28      |  39         | 16
Collie                    |  39      |  71         | 17
Labrador Retriever        |  72      | 182         | 18
English Springer Spaniel  |  18      |  45         | 19
Samoyed                   |  13      |  42         | 20
Dachshund                 |  26      |  81         | 21
Golden Retriever +        |  37      | 158         | 22
American Cocker Spaniel + |  14      | 115         | 23
Miniature Poodle +        |  10      | 159         | 24
------------------------------------------------------------
*Rank based on unadjusted odds ration (an estimate of relative risk) in pure breeds for which there were >=10 cases and >=10 controls. All dogs combined (pure and mixed-breeds) included 1934 cases and 3868 controls. *Risk significantly higher than for all dogs combined. +Risk significantly lower than for all dogs combined. considered "deep-chested" dogs at higher risk of developing bloat. Measurements being obtained in the case-control study, including chest and abdominal measurements using a special caliper, will indicate which aspects of a dog's conformation affect the risk of bloat. The radiographic morphometry study will use another approach to evaluate the importance of body conformation in the risk of bloat. For dogs of about 20 breeds, measurements from chest radiographs will be compared with each breed's risk of developing bloat.

Is the tendency to develop bloat inherited? (Many breeders believe that it is.) The case-control study is providing some information about family history of bloat for each dog, but we believe the proposed study of the patterns of inheritance of bloat will be the first to investigate the genetic factors. Four-generation pedigrees will be analyzed using computer programs designed to discern major gene effects. The effect of inbreeding will also be analyzed.

If the studies are funded, the reimbursement to veterinary clinics for clinical and measurement data will be increased to $50 per case-control pair.

Wanted: Purdue research team urgently seeks bloat cases to enroll in a study of risk factors this spring and summer (1994?). If you know of other veterinary clinics which might participate, please call: (317) 494-7543 (Larry Glickman) or (317) 494-1446 (Diana Schellenberg). We need as many cases as you can provide!


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