|With heart disease at the forefront of many present-day American boxer breeders’ concerns, the ABC Health & Research Committee invited Dr. Bruce Cattanach, Bsc, PhD, DSc, FRS, to give a presentation at the 2001 ABC on the UK Heart Control Scheme for Aortic Stenosis. |
Dr. Cattanach has been a noted breeder/exhibitor of boxers in England since 1949 under the Steynmere prefix. Ch. Steynmere Night Rider had a strong influence on boxer bloodlines in the UK, and English Ch. Steynmere Summer Gold - imported to the US as an adult - appears in many North American pedigrees through his descendents, Chs. Berena’s Gemini Splashdown and Tribute to Fa Fa. Dr. Cattanach is a geneticist by profession, and has specialized in the cause and analysis of genetic defects. Until his recent "semi-retirement," Dr. C. was Director of the Medical Research Council Mammalian Genetics Unit in the UK. He also worked on the genetic effects of radiation in the USA in the 1960s, and in fact, on his return to the UK in 1969 he took a Cherokee Oaks bitch back to the UK to found his present-day Steynmere breeding.
Dr. Cattanach was instrumental in eradicating the crippling, hereditary, neurological disease, Progressive Axonopathy (PA), from the British boxer in the 1980s, and is currently working with British cardiologists and breeders to lessen the very widespread incidence of Aortic/Subaortic Stenosis in British bloodlines. At the end of Dr. C.’s talk, he received a standing ovation from the 200+ people who attended.
Dr. Cattanach has added a postscript to his ABC talk as a result of subsequent discussions of AS on the Showboxer-L e-mail list. The postscript also answers questions and issues raised during Dr. Cattanach’s presentation. It appears at the end of this article.
Editor’s note: The following notes are taken from Slides used by Dr. Cattanach in the course of his presentation. These illustrate his main points. VZ
THE UK HEART CONTROL SCHEME FOR AORTIC STENOSIS PRESENTED AT THE 2001 ABC BY DR. BRUCE CATTANACH
copyright 2001 Dr. Bruce M. Cattanach
Slide 1 The Start/Initial Findings
Slide 2 Actions Taken
Slide 3 Tests for Aortic Stenosis (AS/SAS)
Slide 4 Heart Murmurs, Doppler Blood Velocity and AS
Slide 5 Selection of a Test System
Slide 6 The UK Breed Council Breeding Control Scheme
Slide 7 Summary of Results
Slide 8 What Further Can Be Done?
Postscript to Dr. Cattanach’s ABC talk on the UK Heart Scheme
I have just returned from a trip to find a mass of e-mail writings on my ABC heart talk. The volume has dropped sharply in recent days, and I hesitate to bring up the subject again, especially as my points all seem to have been recognised and some level of agreement reached. But several pertinent questions were asked and require answers and certain other issues perhaps should be emphasised again. So let me try and deal with these -- in sequence:
Ques. 1. Has the severity of cases referred to vet schools changed since the breeding control scheme was introduced?
Ques. 2. Has there been any change among the vets at vet schools in the UK?
Ques. 3. Has there been any change in Boxer lifespan since the inception of the control scheme?
Ques. 4. What pathology data exist?
Ques. 5. How many dogs were involved in the breeding study?
Ques. 6. Low grade murmurs have been found without Doppler evidence of obstruction and vice versa. Does this not call into question the validity of scoring heart murmurs?
Ques. 7. Isn’t Doppler the best test system?
Ques. 8. Is there really a correlation between loudness of murmurs and degree of obstruction?
Ques. 9. Must not the gold standard for AS be based on pathology?
Just an add on: A big difficulty as I tried to point out is that the same words are used to mean slightly different things. Is AS strictly only a narrowing, an obstruction, associated with an increased blood flow through the aorta; or is it also the lumps and bumps, the roughening of the aorta walls that do not restrict blood flow but are manifestations of AS nontheless?
The cardiologists in the UK have recognised all to be the same thing. For me as a geneticist with a very different view from the vets, based on many studies with mouse mutants, this is exactly what I would expect -- a range of effects (irrespective of the exact mode of inheritance); and every single reader will recognise this themselves with everyday Boxer breeding.
Take brindle/fawn; there is a range of brindle effect from near fawn (let's call this grade 1) through to reverse brindle (let's call it grade 6). We can all see this by looking, but if we could not do this directly but had to try and work out what was brindle and what was fawn from hair samples ( like the cardiologists working with ausculation, Doppler, 2D ultrasound, etc), we might conclude that lots of black hair means strong brindle, lesser amounts of black hair probably means brindle, but what about the least amount of black hair?? Some might conclude that such a dog is a light brindle. Others might conclude it is fawn. But there is black hair in the coat of fawns so the exact "diagnosis" is not clear. There is all sorts of scope for argument with an imprecise scoring system.
What the UK system specifies is that we don't want the bad hearts (= reverse brindles) and we will encourage breeding from the best dogs, be they absolutely normal (= fawn) or grade 1s (= the lightest brindles). We all know that some lines tend to be dark brindles and others light brindles. We therefore can select for whatever we want. This applies to AS too.
So, as the astute will have noticed, I presented the UK scheme, its rationale, its problems, etc., so that you in America, should you wish to do anything about AS, will see what we have tried to do, what has gone wrong, what we have had to do to fix things, and in total, avoid all the pitfalls that we met. The concept and types of problems apply to BCM as well. You don't at all have to follow the same route, but standardising the diagnosis across the country is one essential need, and setting up an agreed written protocol or guidelines for breeding, with flexibilty to meet different situations, is another. This applies, as far as I am concerned, across the whole spectrum of dog abnormalities, not just with regard to hearts.
About your dog: The selective breeding is the key -- a fair system that everyone can use. You don't want to continue testing for the rest of time, do you? One might say that this is the case for PRA. PRA testing has been going on for 30 years or more.
Bruce M Cattanach