SAS: The ARC Health Committee Report

from The Rottweiler Quarterly second quarter 1996

by Dr. Susan Reis

The health committee article for this issue of the ARK newsletter and the Rottweiler Quarterly is about SAS and, especially the importance of proper testing procedures to identify the condition. Another health committee member, Carol Krickeberg, has written an article at the request of ARC's breed columnist Dorothy Wade, to the AKC Gazette about her experiences with SAS in her dogs. (Editor's note.- Carol Krickeberg's report on her experiences appeared in this newsletter this spring and also in the AKC Gazette, the ARK and the TRQ).

The most striking thing about SAS is that this condition may give no outward warning of impending problems. Your initial introduction to SAS may be the sudden death of an apparently healthy dog, and this is why SAS in our breed is of so much concern to this committee. Sudden death is not the only clinical presentation of SAS, just the most dramatic.

The defect and accompanying clinical signs may also range from mild to severe and can ultimately develop into congestive heart failure and death. Some dogs may have very subtle signs associated with slight heart murmurs without significant clinical problems or a reduction in normal activity or life expectancy. Unfortunately, these dogs may also serve as a potential source of SAS in the breed.

There are many health issues that this committee wants to address, and in order to gain a reasonable approach to this goal, we thought about priorities. The top priority goes to those conditions that are fatal to our dogs, and heart conditions immediately come to the forefront. Other high priority conditions are cancers and the fragile immune system of our dogs. There is a feeling I get from talking to Rottweiler owners and breeders that more health problems are appearing all the time in our breed. We need to keep this in perspective .... more Rottweilers are appearing as well. All we need to do is look at the increase in numbers of Rottweilers registered with AKC over the past 5 years. An increase in incidences of medical problems would logically accompany such a large increase in possible medical targets, especially if we are not doing the prebreeding evaluations we should to detect and control these problems. The same relationship could be made with a top stud dog who is allegedly "throwing" medical problems. Once again, if you increase the numbers (in this case, in puppies and different genetic combinations), you increase the odds.

The problems we see in our breed are inherent with a limited gene pool, and I don't feel we can single out a bloodline to be the source or to be totally free of any medical problems. It's way past time for laying blame and absolutely time to get on with the work of trying to help our dogs ... all of them. . Carol summoned great courage to deal with this problem in a Forthright manner and without the needless and extremely harmful finger-pointing that so often accompanies the discovery of such a problem. She went even further and began to investigate this condition on her own to learn more about SAS and to share this information with the rest of us. Although our committee works on a premise of not releasing names of people or dogs, Carol felt strongly about having her name released. Her point is that as breeders we need to be up-front with our own problems in order to begin the process of eliminating them from the breed. I cannot commend her enough. I'm proud to be working with her on this committee and I look forward to having her article printed this spring for those of you who do not subscribe to the Gazette.

While working with Carol on this project, ARC President, Cathy Thompson, gave me the name of Dr. Michelle Goodman ... the Chairman of the Golden Retriever Club of America Health Committee. Dr. Goodman is actually a veterinarian reproduction specialist with ICG (International Canine Genetics), but, as she told me during our first phone conversation, SAS has become such a problem in her breed that cardiology has become her second area of interest. The information I received from Dr. Goodman relevant to the status of SAS in her breed was very disturbing and could very well mirror the path our breed will follow if we do not begin to address this problem head-on.

Dr. Goodman has been working with veterinary cardiologists across the nation. Interestingly, our own health committee members are working with some of the same people. These people include Dr. Dave Sisson at Illinois. Dr. Bonagura at Ohio, Dr. Bill Thompson at UC Davis, Dr. Matt Noller at Texas A&M, Drs. David Knight and Donald Patterson at Penn, and Dr. Wendy Ware at ISU. In addition, Dr. Dana Buscio has been very helpful in our efforts. What the studies done on Golden Retrievers have revealed include that from 30-80% of the purebred Golden retriever population is likely affected by SAS although in their breed, luckily less than 1% are clinically affected. The numbers for Rottweilers are not yet available, but one difference between our two breeds is sudden death. It does not appear to be as severe in the Golden Retriever. Dr. Goldman described what is called "trivial SAS" in the Golden Retriever, which commonly has subtle Grade 1-2 heart murmurs associated with cardiac flow abnormalities that are difficult to detect, making the condition difficult to diagnose, and is partially responsible for the extent to which it is now being found in their breed.

The mechanics of changes in the heart itself that occur when a dog has SAS are dependent upon the severity of the stenosis (narrowing of the outflow tract from the left ventricle of the heart below the aortic valve leading to the aorta). In order to get a better picture, a comparison could be made to water flowing through a garden hose. The normal speed of water flowing from an unobstructed end of hose would be similar to normal blood flow into the aorta from the left ventricle in an unaffected heart. As you make the opening of the hose smaller (i.e. place your thumb over part of the end of the hose), the speed with which the water leaves the hose increases in order to pass the same volume of water through a smaller opening. This would simulate a stricture such as is present in a case of SAS. In order to push the same volume of water or blood out over a unit of time, the workload on the pump (heart) increases. In hearts affected with SAS, over time the muscle mass of the heart increases and additional problems can develop including arythymias. These irregular heart beats can result in insufficient blood flow to the heart muscle itself and can develop into ischemia (lack of blood supply) to the heart. This is what is suggested to occur in cases of sudden death. Other dogs with less severe forms may develop congestive heart failure and the health problems that accompany it later in life. Since severity of the stenosis can vary greatly, this explains the wide range of clinical presentations of SAS.

Some of the causative factors involved in misdiagnosis, or perhaps non-diagnosis, include incorrect or inadequate diagnostic technique, inadequate equipment, improper use of equipment, and a lack of a standard set of parameters with which to test for consistent, reliable diagnosis. Sadly, the incorrect clearance of affected dogs has kept the problem in the gene pool via a carrier state in the Golden Retriever and this could well be the scenario in our breed. Diagnosis of SAS is almost an art. In spite of available technology, without the proper expertise to evaluate heart function, an affected dog can be called "clear". This probably occurs far more often than we care to admit. I was told of an incident of two stud dogs (the breed involved is of minor importance) that were cleared for SAS by veterinary internists at a highly respected university veterinary teaching hospital, that were subsequently checked and found to have indisputable SAS by veterinary cardiologists. Some of the top cardiologists we talked to strongly feel that auscultation (listening to the heart with a cardiac stethoscope) with the dog at rest and after exercise is essential to a proper cardiac evaluation. The echocardiography test itself, using Doppler technology, is also not infallible. A dog diagnosed and affected with SAS can actually get a normal readout if the probe placement is incorrect. In other words, the correct performance of a complete cardiac evaluation is crucial to the determination of an "affected" or "clear" dog.

Additional current work being done on this condition is the determination of heritability. It is felt that SAS is a polygenic condition, which can make it difficult to determine predictable genetic transmission patterns needed to enable geneticists to make reliable breeding recommendations for carrier dogs or dogs related to affected or Carrier dogs. At this time there is not enough data being gathered to help researchers help us with this problem. Texas A&M researchers are presently working on gene mapping and the identification of gene markers for SAS. This could be a very significant development in helping us bring this problem under control. An important element needed for the study of SAS is the work of a population geneticist armed with sufficient numbers and data to come to reliable conclusions about the genetic characteristics of SAS. An organization known as the Institute for Genetic Disease Control is working with several breed clubs to develop an open registry from information submitted voluntarily by interested owners and breeders. The organization's biggest need is a population geneticist and their biggest obstacle second to voluntary cooperation is sufficient funding to accomplish their goals.

Dr. Goodman is currently working with several of the cardiologists named earlier to create a form that dog owners could take with them when their dog is being tested for SAS. This form would be filled out by the cardiologist performing the evaluation and would essentially describe the test that was performed on the dog. It is hoped a more consistent cardiac evaluation will be performed on a greater number of dogs utilizing this form. The proposed form is to have an original and 1-2 copies; the original for the client, the first copy to the cardiologist, and the second copy could be submitted to a registry such as IGDC for pedigree analysis, if desired.

This is one condition we can't test for to get the results we want (i.e., good fair, excellent, etc.) We need to face reality...... reality being a condition that is known to be fatal in our dogs.

The next question then is what do we do if we test our dog and he tests clear with no known positive relative(s), clear with dogs positive or suspected in his background, clear with positive siblings or half siblings, or he tests positive himself In the Golden Retriever, positive dogs are eliminated from the breeding pool, no exceptions. From there the next step is test breeding of siblings of positive dogs, which requires a huge commitment from the breeder in terms of culling positive offspring and identifying the carrier sire or dam. Presently, it is felt that two carrier (non-positive) animals are needed to pass SAS to their offspring. The work being done on gene mapping and DNA markers may be the key to identifying the carrier animals, especially siblings of positive animals, without eliminating an entire litter related to a positive dog. Until DNA testing is available the success of at least eliminating clinically affected or test positive dogs rests with the integrity of the breeder' s program. Open communication with other breeders so that lines that would not make a good cross could be avoided or approached cautiously. Ideally, puppies from such a breeding would be tested whether sold as show or pet. Whether this is feasible or not is a big, question mark, but it may be a way to save an animal valuable to a breeder's bloodlines.

A request made by several of the veterinary cardiologists we are working with is for owners who lose a dog suddenly to submit tissues (heart and/or lungs) to then for autopsy by a certified cardiologist. It might be the one act of love we can do for our dogs that might help us feel that our dog's death was not meaningless. For those who are willing to work with these specialists, please contact a health committee member for names, phone numbers, etc. We will be happy to get you in contact with the qualified people and to help in any way possible. I realize it is hard to be motivated to test for a condition that you have not had any experience with ... possibly by doing the testing now, we can avoid that experience.

One result that I fear may come from this series of articles is the generalization that any sudden death occurring in our breed is attributable to SAS. This tendency to generalize things we don't understand or are afraid of emphasizes the need for proper testing of breeding animals. We also need to follow-up on sudden deaths ... not only to diagnose SAS if it is present, but also to clear a dog if it didn't have SAS, and also to learn more about other conditions that can cause sudden death. Generalizations, innuendoes, half-truths, etc. have no place in trying to find answers to the medical problems in our breed. They only hurt and mislead.

Finally, SAS is not the only heart condition we face in our dogs ... it just happens to be an insidious and sometimes fatal condition that we and our dogs can't live with, nor can we ignore it. If you have any questions, comments or concerns about heart conditions or other health issues, please contact me or any other health committee member at any time.