Bloat Notes

Reprinted with permission from the December, 1993 issue of Bloat Notes (News form the Canine Gastric Dilatation-Volvulus Research Program at Purdue University)

Veterinarian's Viewpoint By Gary C. Lantz, DVM

(Dr. Lantz, Professor of Small Animal Surgery, Purdue University School of Veterinary Medicine, launches a new feature in the newsletter with his comments about bloat. He has had years of experience treating dogs with bloat and conducting clinical research, and is a co- investigator in the current epidemiologic studies at Purdue.)

Bloat is a life-threatening disease in dogs. In order to provide a greater understanding of this problem and to emphasize the urgency of seeking medical treatment when bloat occurs, we have answered some questions that are commonly asked.

What is bloat?

Bloat is a gastrointestinal disease affecting primarily large and giant dog breeds and has an approximately 30% mortality rate. It is a rapidly progressing disease that can occur at any time. It requires immediate medical attention. In brief, the stomach distends and rotates for reasons as yet unknown. The distended, rotated stomach compresses two large veins located in the abdominal cavity that return large volumes of blood to the heart for recirculation through the body. When this venous return to the heart is reduced in bloat, the heart does not pump a normal volume of blood to the body tissues. Therefore, body cells are deprived of normal amounts of oxygen and nutrients. Body functions begin to fail. The patient goes into shock and this requires immediate treatment.

What are other names for bloat?

Bloat is also known as canine gastric dilatation-volvulus CGDV), gastric rotation, gastric torsion, or gastric distention. Actually the term "bloat" has been applied to two different clinical findings that are probably part of the same disease process.

Bloat with a distended and rotated stomach requires surgery as part of the treatment. Bloat with a distended stomach that is not rotated may not require immediate surgery. The clinical signs of each type of bloat are identical, and each can cause rapid death. The distinction between the bloat types is made on x-ray evaluation of the stomach and not by clinical examination alone.

What causes bloat?

The specific cause(s) for bloat have not yet been determined. Theories include: various factors contributing to the abnormal anatomy and/or function of the stomach; various types of dog foods; eating and drinking large volumes of food and water before or after periods of exercise; and body conformation. Genetics may play an important role. A combination of factors may be involved.

What are the clinical signs of bloat?

Progressing from early to late signs:

1. Pacing and restlessness
2. Head turning to look at abdomen
3. Distention of the abdomen
4. Rapid, shallow breathing
5. Nonproductive vomiting
6. Salivation
7. Recumbent: semi-comatose or comatose

The clinical signs can begin suddenly, at any time, and may progress rapidly to coma and death. If bloat is suspected, it is imperative that the dog be examined by a veterinarian immediately.

Can it wait until later? My schedule is full.

ABSOLUTELY NOT! The progression of shock in a bloated dog can be very rapid. A perfectly normal dog may be dead from this disease as soon as 2 to 3 hours after onset of clinical signs. If this disease is suspected, the patient must be examined by a veterinarian immediately. The earlier a patient is diagnosed and treated, the better are the chances for survival.

How is bloat treated?

The first step is the treatment of shock. This is accomplished by decompression of the distended stomach (by inserting a needle through the abdominal wall and/or passing a tube into the stomach via the oral cavity) and by the administration of intravenous fluids and other drugs to improve blood circulation throughout the body. Vital signs and other body functions must be monitored carefully.

Surgical correction of the rotated stomach follows and can usually be performed within 2 hours of presentation of the patient to the veterinarian. (Some patients in the earlier stage of bloat may be ready for immediate surgery. Other patients in the later stage of bloat may require a little longer period of medical stabilization before surgery is performed.) As part of the surgical procedure, a gastropexy is performed, i.e. the right side of the stomach is attached to the body wall. This attachment will heal and become permanent so that the stomach rotation will not recur. Several effective gastropexy techniques are available. Gastropexy has a 3% to 5% failure rate, that is, a permanent adhesion does not form. If gastropexy is not performed, the recurrence rate of bloat is about 68% to 80%.

I can take my dog home right after surgery and it will be OK, right?

Intensive postoperative care in the hospital is needed for several days. The bloat patient has been through a very traumatic disease process and a major surgery. Also, many complications can arise in the first 3 to 4 postoperative days. Most patient deaths occur during this time period.

How can I prevent bloat from happening?

Since the cause of bloat is unknown, specific recommendations to prevent it cannot be made at this time. Current recommendations include pre-moistening dry food to reduce stomach distention after eating, dividing the daily ration into 2 or 3 smaller meals, and limiting activity for at least 1 hour before and after eating.

What should I do to prepare for a possible episode of this disease?

You should know the clinical signs of bloat that are listed above. You should know where the nearest emergency veterinary medical facility is. Remember that a gastropexy will probably prevent rotation of the stomach in the future, but stomach distention can still occur. Severe distention without stomach rotation has identical clinical signs and may be just as fatal as stomach distention with rotation.

What can I do to help promote bloat research?

Donations designated for bloat research may be sent to the Morris Animal Foundation, 45 Inverness Drive East, Englewood, CO 80112-5480, or to CGDV Research Program, School of Veterinary Medicine, Purdue University, W. Lafayette, IN 47907-1243.

Purdue Bloat Research is Expanding!

Dr. Larry Glickman (Principal Investigator) was notified that the Morris Animal Foundation approved the new grant for bloat research at Purdue through August, 1995. Objectives and status of the studies:

Radiographic Morphometry Study

Objective: Use radiographs to assess chest conformation as a risk factor for bloat (see following article).

Inheritance Patterns of Bloat Risk

Objective: Characterize the role of inheritance in the risk of developing bloat. Breeders will be asked to supply pedigrees and other information.

Practitioner/Owner Case-Control Study

Objective: Expand the ongoing study of risk factors -- those that predispose a dog to bloat and those that precipitate an episode. More veterinarians are being recruited to provide data from dogs with bloat (cases) and those without bloat (controls).

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.

Are Deep-Chested Dogs More Susceptible to Bloat?

In a previous study funded by the Morris Animal Foundation (Bloat Notes May, 1993 - Mastiff Reporter June, 1994), we examined the pattern of occurrence of bloat for 5802 dogs. Pure- breed dogs were 3 times as likely to develop bloat as mixed-breed dogs, and in general, the larger the breed, the greater the risk. However, even among breeds of similar body size, there were marked differences in risk. For example, the "Setter" breeds (Irish and English) were at relatively high risk, while the "Retriever" breeds (Chesapeake, Labrador, Golden) were much less likely to bloat. Also, the Basset Hound had the 6th highest risk of bloat among all pure breeds despite the fact that it usually weighs less than 50 lbs.

This pattern of breed risk led us to suspect that conformation of the chest (and probably abdomen) is an important factor in predisposition to bloat. We hypothesized that breeds typically having a greater chest depth/width ratio would be more likely to bloat because the deeper chest and abdomen would allow the stomach and its ligaments to stretch in the ventral direction, especially when weighted down by water and ingesta. Chronic stretching would then increase the probability of twisting (volvulus, torsion), especially when the stomach is full and a rotational force is exerted, as when the dog rolls over or exercises.

This hypothesis is being tested in a second 2-year study funded by the Morris Animal Foundation and by donations from several breed clubs and individual donors. Since the risk of bloat for many pure breeds has been determined, we now need to characterize chest size for the same breeds and compare the two measures.

Chest size is currently being assessed by utilizing thousands of chest radiographs that were taken on dogs that were seen at the Purdue Veterinary Teaching Hospital since 1980. The goal is to determine the average adult chest size, namely depth, width, length, for each pure breed for which we have information concerning bloat risk and then to relate the measures of chest size with breed risk. While the study will not be completed for another 6-12 months, the preliminary findings are so interesting that we felt you should be aware of them.

When the risk of bloat for each of 7 pure breeds is plotted on the horizontal axis and the chest depth/width ratio on the vertical axis, the two measures appear to be highly correlated. There is an almost linear increase in bloat risk by breed with an increase in the chest depth/width ratio for those 7 breeds. In this example, 63% of the variation in bloat risk can be explained by a change in the chest depth/width ratio alone!

A word of caution: these are only preliminary results which need to be confirmed in a much larger number of dogs and dog breeds. Also, in the practitioner/owner case-control study of risk factors, we are measuring chest size (and abdominal size) in dogs that had bloat and comparing these with the same measures in dogs of the same breed and age that did not have bloat.

Studies such as those described above will enable us to better understand the genetic and environmental determinants of bloat. This knowledge is critical in order to develop meaningful recommendations to breeders to prevent bloat. As for diseases like heart disease, cancer, and diabetes, which are multifactorial in their origin, a variety of research studies in dogs will be needed to shed light on the causes of bloat. This will take time, collaboration, and a continuing commitment by breeders and veterinary researchers.