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ABC 2003 – HEALTH SEMINAR SUMMARIES

Virginia Zurflieh, ed.

The following are summaries and comments on the 2003 ABC Health Seminars sponsored by the ABC Health & Research Committee (HRC). My thanks to Dr. Theresa Garton for filling in the blanks in my notes on the presentations, and we can all be grateful to HRC members Dr. Joyce Campbell, Dr. Ted Fickes, and Dr. William Truesdale (also president of the ABCF) for arranging for these "cutting-edge" ABC seminars. Following the summaries is the news we’ve all been waiting for – ordering information for the videotapes made from the seminars by Judy Voran!

Boxer Cardiomyopathy – NOT!

The last word from Dr. Kate Meurs on the subject of BCM/FVA, which she is now calling "ARVC" (Arrhythmogenic Right Ventricular Cardiomyopathy – also a human disease), is that it's definitely an "electrical" disease, not a heart muscle disease like dilated cardiomyopathy, and is caused by a dominant gene with variable penetrance.

Diagnosis is based on 1) the presence on a Holter tape (24-hour EKG) of ventricular premature complexes (VPCs); and after death, 2) by a necropsy that shows fatty infiltration into the right ventricle. In more severely affected dogs, the fat may also infiltrate the left side of the heart and/or the septum. Current treatment for ARVC consists of medication with sotalol or Mexilitine/Atenolol, but Dr. Meurs said that treatment may not reduce the risk of sudden death, even in those dogs that are having fainting spells! She again stressed the importance of annual Holter tests, and urged breeders NOT to make irrevocable breeding decisions on the basis of only one Holter test. Dr. Meurs also said that it’s very important to have our dogs’ Holter tapes read by a board certified cardiologist, because machine-read tapes produced by a lab may contain artifacts that are incorrectly interpreted by the computer as VPCs. Not incidentally, Dr. Meurs is now reading Holter tapes for all comers, not just the participants in her studies at Ohio State. The instructions are available in printable form on the BU – just check for the link.

Not incidentally, Dr. Meurs is now reading Holter tapes for all comers, not just the participants in her studies at Ohio State. The instructions are available in printable form on the BU – on the Links page or the Health Tested Boxers page.

Aortic Stenosis Bombshell!

After she completed her report to the ABC membership on ARVC – formerly called BCM/FVA – Dr. Meurs reported on her latest study of subaortic stenosis (SAS). The outcome of this study was a real shocker for those breeders accustomed to considering an aortic blood velocity of 2.5 ml/sec to be completely beyond the pale and a sure sign of aortic stenosis in any boxer whose Doppler echo resulted in such high numbers.

Dr. Meurs’ study was based on three groups of dogs: 1. Boxers with soft murmurs; 2. boxers without murmurs (Meurs said she had great difficulty in finding boxers without murmurs!); 3. non-boxers and mixed-breed dogs of the same weight as boxers.

Some of Dr. Meurs’ conclusions, in no particular order: 1. The younger, more excitable dogs were more likely to have a high velocity and a murmur. 2. Increased blood velocity can be caused by a) stenosis, b) excitement, and c) pregnancy/heat.  3. Her most important discovery was that the non-boxers in the study uniformly had larger aortas. 4. From that finding, Dr. Meurs has concluded that boxers are "different" than other breeds, as regards SAS. In other words, most boxer murmurs may be purely PHYSIOLOGIC in nature because of their smaller aortas! Dr. M. said that most of the information we have on SAS to date is based on studies of Newfoundlands, and no one knows if we can extrapolate to other breeds, such as boxers.

Meurs' current recommendations (based on this study) are that a blood velocity of 1.7 to 2.5 can be acceptable IN A BOXER, if there is no turbulence or fibrous ridge/ring detected on a color-flow Doppler echo. (The fibrous ridge may or may not be noticeable on Doppler, but it is definitely what is looked for on autopsy to confirm or disprove the presence of SAS.) A velocity of 1.7 was historically chosen as "normal" because "that's what you can hear" – i.e. a blood velocity over 1.7 can be heard with a stethoscope as a murmur.  Again, Dr. Meurs said her study indicated that a blood velocity of 1.7 to 2.5 "can be normal" in a boxer, in the absence of blood turbulence or a fibrous ridge in the aorta.

Dr. Meurs noted that the UK Heart Control Scheme for Aortic Stenosis, which is based on identifying and grading heart murmurs via auscultation (listening with a stethoscope) "may just be removing dogs that are more excitable" from British breeding programs. (We wonder how our British colleagues will react to the suggestion that a lot of boxers without SAS are being needlessly removed by the UK Control Scheme because auscultation isn’t the best diagnostic tool, considering that pro-Doppler/anti-auscultation North Americans have been insisting for years that a lot of dogs with SAS were being missed by the UK Control Scheme because auscultation wasn’t the best diagnostic tool…)

Dr. Meurs also urged breeders NOT to discard otherwise outstanding boxers with borderline values, but instead, to take care to breed them to dogs or bitches with lower flow rates. (That advice was in keeping with the "vertical" breeding program described by geneticist Dr. Jerold Bell in his ABC presentation on canine genetics.) Dr. Meurs responded to a question about OFA certification by saying that the OFA was fine for hips, but "too black and white" to be appropriate or accurate for certifying a dog "clear" of heart disease. Meurs’ findings on SAS are so new that US cardiologists have probably not come to a consensus yet on her research, BUT we do know at least one boxer-savvy board certified cardiologist in Florida who has apparently accepted her "excitability" theory, and as a result, reversed a diagnosis of SAS.

Dr. Natasha Olby on Degenerative Myelopathy

Dr. Natasha Olby of North Carolina State University gave an informative and exceptionally detailed talk on Degenerative Myelopathy at the 2003 ABC. Unfortunately, her presentation didn’t offer much hope for those boxer owners whose dogs are currently affected: After years of studying German Shepherd Dogs, there is still no cure, no sure knowledge of whether DM is inherited or not, and not even a definitive diagnosis outside of an autopsy. Any diagnostic tests used are only to rule out other diseases. Dr. Olby did say that the MRI may prove to be a diagnostic tool in the future, and noted that there was a theory among some researchers that a possible cause of DM in German Shepherds was "Doggy MS" (multiple sclerosis).

The breeds most often affected are GSDs, Pembroke Welsh Corgis, Boxers, Chesapeake Bay Retrievers, and Irish Setters. Dr. Olby devoted the last part of her talk to suggestions for making life easier for a dog with DM. Those included keeping the dog on non-slip surfaces; building ramps to avoid steps; feeding from raised containers; and using "booties" for foot protection. She also suggested physical therapy in the form of short, regular walks, after other diseases have been ruled out. Some researchers feel that supplementation with anti-oxidants (vitamin E, B-vitamins, amino caproic acid) could be beneficial, but Dr. Olby has not found amino caproic acid to be effective.

Intriguing aside: Several months after the ABC, a veterinarian who had attended Dr. Olby’s talk called to suggest that we checkout the July 14, 2003 issue of Newsweek. There’s a feature article in that issue that suggests that statins, a class of powerful cholesterol-lowering drugs long known to fight heart disease, "have shown promise in combating a number of other ailments," including Alzheimer’s, osteoporosis, and multiple sclerosis. BU will try to contact Dr. Olby to get her take on statins and "Doggy MS." In the meantime, back issues of Newsweek are as close as your local public library.

Dr. Jerold S. Bell – Developing a Healthy Breeding Program