Canine Gastric Dilatation-Volvulus (Bloat)

School of Veterinary Medicine

Purdue University, West Lafayette, IN 47907-1243

Research Updates from the Purdue University Prospective Study of Canine Gastric Dilatation-Volvulus (GDV)

November 9, 1998

In 1994, the Section of Clinical Epidemiology of the Purdue University School of Veterinary Medicine in West Lafayette, Indiana initiated the largest prospective study of dogs ever attempted. The objectives of this study were to: 1.) Measure the frequency of GDV in several breeds that were thought to be at high risk of the condition, and 2.) Identify host, environmental, and dietary risk factors for GDV, which if known, would facilitate implementation of effective prevention programs. This study followed on the heels of at least five retrospective studies conducted by researchers at Purdue that offered some clues as to what are the risk factors for GDV. Also, several national health surveys conducted by Purdue showed GDV to be the second leading cause of death following cancer, in large and giant breeds. However, because the results of retrospective studies could be biased by the selective and inaccurate recall of past events by owners of dogs that had already developed GDV, it was felt that a large prospective study was needed to answer important questions about what causes GDV. The prospective approach to characterizing risk factors for diseases is often used in human medicine, despite the fact it is extremely expensive and requires many years of observation. One example of this approach is the study of men in Framingham, MA to identify the multiple risk factors for heart disease. The idea for a prospective study in dogs was supported by funding from the American Kennel Club Canine Health Foundation, the Morris Animal Foundation, 11 breed clubs participating in the GDV study, and by generous donations from dog owners, breeders, and veterinarians, concerned about the impact of GDV on canine health.

The general design of the Purdue University Prospective Study of Canine GDV has been described in some detail in previous issues of the Purdue Bloat Notes that are available on this web page. Bloat Notes. Briefly, starting in 1994, the Purdue research staff attended dog shows around the country for seven large breeds, namely the: Akita, Bloodhound, Collie, Irish Setter, Rottweiler, Standard Poodle, and Weimaraner, and for four giant breeds, namely the Great Dane, Irish Wolfhound, Newfoundland, and Saint Bernard. At these shows owners were asked to participate in a prospective study in which they would agree to have us measure the dogs, complete a detailed questionnaire concerning their dog's medical history, environment and management, diet, personality and temperament, and keep us updated on this information as well as on the vital status of their dog. If the owners agreed to participate, measurements were made of the dog and the owner completed a short form indicating whether this dog or any of its first-degree relatives had ever developed GDV. All dogs were then followed closely by the Purdue staff using both repeated telephone contacts with the owners and by mailed questionnaires. The intensive follow-up period for this part of the study ended on October 1, 1998, although information continues to be received from owners of dogs in the study.

Our intent at the onset was to provide all of the participants and the contributing sponsors with reports regarding the status of the study and with results, as they became available. We expected that once all of the information was obtained by October 1, 1998, it would take a minimum of one additional year to analyze these data and probably another year or more to publish the results in a veterinary journal. Therefore, because of the anticipated delay, it was our intention to publish interim reports of our findings in Bloat Notes and on the Internet. We have recently learned from the editors of the Journal of the American Veterinary Medical Association (JAVMA) that dissemination of our findings in this manner would render them unsuitable for publication in that journal and probably in many other journals as well. In a recent issue of JAMVA (volume 213, pages 1091-3, 1998), the editor wrote that "in essence, that neither the manuscript being submitted nor any of its parts may have been published elsewhere or may be under concurrent consideration by any other publication. Examples of other publications include journals, symposia, proceedings, newsletters, and books, regardless of whether they are peer reviewed". We and others in academia interpret this to mean that providing dog owners with information about our studies on GDV in a timely manner, particularly the findings, would severely limit our future opportunities for disseminating this information to our colleagues in veterinary medicine. Therefore, we see no choice, but to ask all those who have supported our efforts on GDV to be patient. We will continue to provide you with updates on GDV, including research conducted at other institutions throughout the world. At his time, however, I would like to just provide a few details about who participated and what we know now that could be used to prevent dogs from developing this dreaded condition. If a journal eventually decides that sharing this important information with dog owners now violates their publication policies, so be it. We think that anything that could save a dog's life now is worth that risk.

There were a total of 1920 dogs without a prior history of GDV that participated in our study. The breakdown of dogs by breed is shown in the table below. These 1920 dogs contributed a total of 3357.6 dog-years of follow-up information (following one dog for one year = one dog year). Among these dogs, 86 or 4.5% developed a first episode of GDV for an incidence of 26 per 1000 dog years. The average age of the dogs at entry into the study was 3.2 years while the average age of the 86 dogs that developed GDV was 5.5 years. Since the dogs in this study were relatively young at the start and because the risk of developing GDV increases markedly with age, we think this estimate of the incidence of GDV is very conservative compared with what we would have observed if we followed these dogs longer. The six breeds with the highest incidence of GDV in decreasing order were the Great Dane, Akita, Bloodhound, Weimaraner, Standard Poodle, and Irish Setter. For the 216 Great Danes that had an average follow-up time of only 2.5 years, nearly 12% developed GDV. Assuming that these Great Danes live to be 10 years of age, we conservatively estimate that more than 50% will eventually suffer an episode of GDV!! This is quite alarming given that nearly 25% of dogs can be expected to die during or shortly after an episode of GDV and it is consistent with previous findings that GDV is one of the leading causes of death in many giant and large breeds of dogs.

What use can sharing this information with dog owners be at this time? I believe if the risk of GDV developing in a dog's lifetime is high, then it is appropriate for owners and veterinarians to consider performing a prophylactic gastropexy (a surgical procedure to prevent the stomach from rotating) in order to prevent a first episode of GDV from occurring. Gastropexy has been shown to reduce the risk of recurrence of GDV by about 95% following a first episode, and it would be expected to be at least as effective when performed on dogs at high risk of GDV before they ever experience GDV. However, I would not recommend that prophylactic gastropexy be done unless the dog were surgically neutered, so as not to increase the pool of dogs in a breed that are prone to develop GDV. Persons considering prophylactic gastropexy for their dog should discuss the procedure with their veterinarian and with owners of dogs that have had this procedure.

Our immediate objective is to complete the statistical analyses of the huge amounts of information we have collected on the 1920 dogs in the GDV study as quickly and thoroughly as possible. We anticipate rather than waiting for all of the analyses to be completed, to prepare the results for publication in several stages. In the first stage we will describe in detail the methods, study population, and incidence rates of GDV as a function of breed, and family history of GDV. In the second stage, we will examine the influence of personality/temperament, body confirmation, and management of the risk of GDV. In the third stage we will examine the role of different diets and feeding patterns on GDV risk. Finally, we will perform a detailed analysis of the potential benefits and risks for prophylactic gastropexy. We hope you will be patient and continue to provide support for this important research being conducted on GDV at Purdue University. In the meantime, we would like to acknowledge support from the following individuals and organizations whose donations have been received since January, 1998 - Donors & Supporters of CGDV Research at Purdue

Without your generous support, we would not be able to continue this research. It is our hope in the future to expand these epidemiologic studies to diseases such as cancer, cardiomyopathy, hypothyroidism, etc, in which multiple factors such as environmental insults, diet, vaccinations, and genetics all interact to determine the risk that any individual animal will be affected. Such complex studies require a team of dedicated researchers who are willing to devote the time and energy needed until a prevention strategy is possible. We see this as a complement to the worthy genetic and clinical research that has been supported over the years by the AKC Canine Health Foundation, by the Morris Animal Foundation, and by dog owners and breeders.

Sincerely,

Larry Glickman