Editors note: This
is the British plan for the control of aortic stenosis, sent to us by Dr. Bruce Cattanach,
a geneticist who was also instrumental in eliminating another hereditary boxer health
problem in England. The following is an explanatory note about the plan for American
Scheme with a copy of a Handout Sheet for new puppy owners. Note
that it was developed for the UK situation and it has worked. We no longer have many young
Boxers being referred to cardiology units, and the mean parent grade correlates with mean
Bruce M. Cattanach, Steynmere Boxers, UK
RECOMMENDATIONS FOR THE
AORTIC STENOSIS (October 1993)
The following points should be noted:
- The revised recommendations being proposed
are based on a number of veterinary conclusions, some of which have been modified in the
light of recent research findings. Further developments are possible. However, it should
be stressed that, as initially, the recommendations are liable to err conservatively, this
being necessitated by the observed high incidence of dogs with heart murmurs and the need
to avoid excessive restraint upon breeding programmes.
- Recommended actions are based upon the
identification of normal, rather than affected dogs. This is warranted by
In the case of dogs
with murmurs consistently no louder than Grade 2, Doppler echocardiography may be a
further option. Those with blood velocities below 2.0 m/s may, for the present, be
considered suitable for breeding. Other useful Grade 2 dogs might, for the present, be
available for stud to a strictly limited number of bitches. These bitches should be
murmur-free or have at the most only grade 1 murmurs. Dogs with Grade 3 or louder murmurs
should never be considered for breeding purposes, even if they have blood velocities below
3. Bitch owners are strongly advised to use
only tested and proven normal dogs at stud.
4. Dog owners are advised to offer only
tested and proven normal dogs for stud purposes and ensure, before accepting bitches for
service, that their owners are complying with the recommended control procedures. At
owners' risk, stud services could be provided for untested, non-show bitches both of whose
parents are murmur-free or have only grade 1 murmurs.
5. Stock incidentally identified as having
heart abnormalities other than aortic stenosis, eg, cardiomyopathy or pulmonic stenosis,
should not be considered for breeding purposes.
B. In the case of young stock,
ie, under 12 months of age:
Puppies aged 6 - 12 months can usefully be tested in the same manner as adults but the
results must be interpreted with discretion. Because aortic stenosis develops
progressively it cannot be assumed that those that are free of murmurs or have only grade
1 murmurs will be found to be so as adults; their prospects may nevertheless be considered
relatively good. On the other hand, those found to have grade 2 or louder murmurs are
unlikely to become suitable prospects for breeding purposes, and may be at risk of
developing the clinical effects of aortic stenosis in later life. The testing of
puppies is strongly recommended. Their retesting as adults is essential, however.
To aid breeders implement the recommended breeding control procedures, a list of dogs
which are free of heart murmurs (Grade 0) or have only minor murmurs (Grade 1) is
continually being collated and updated. Copies are available from the Breed Council
secretary or secretaries of breed clubs.
Most breed clubs hold heart-testing clinics
with designated cardiologists in attendance at one or more of their shows each year.
Private testing can be obtained by referral through owner's vets. A list of designated
cardiologists may be obtained from the Breed Council secretary, or from breed club
secretaries or heart delegates.
Cardiologists may advocate ultrasound
scanning and Doppler echocardiography for dogs with grade 3 or louder murmurs as a means
of evaluating the severity of the condition, ie, for purely veterinary reasons.
Baby puppies aged 8 - 12 weeks commonly
have minor "flow" murmurs which usually disappear by about 16 weeks. These are
not known to be associated with heart disease in the adult. However, puppies with loud,
harsh murmurs should be referred through one's vet to cardiologists for evaluation.