The breed clubs have failed to address this issue for years. Many find this discrepancy very disturbing.
This is exactly why breed club registration for puppies means NOTHING except the barest MINIMUM of 'qualifications' a breeder is showing and only is the very start of researching a breeder throughly.
It's why you not only want to see the cardiac cert for the sire and dam, you also want to know the ages of both. I know of prominent breeders who will breed *one year old dogs* with no cardiac testing claiming if it comes from good lines it will be fine. Yet breeders themselves are the first to note that genetic possibility means even exemplary parents can sometimes produce an offspring affected with early-onset MVD -- or SM.
That is the whole point of both cardiac testing and following the MVD protocol, which recommends not breeding a dog under 2 to 2.5 years old whose parents also remained heart clear til age 5. Anyone who says they know better than the protocol is knowingly dicing with genetic probability in -- excuse the term -- a cavalier way.
I'd suggest anyone similarly baffled by the two prominent national US breed club's attitudes write to the club asking this same question.
Incidentally the UK club also chose to ignore the strong recommendation of its a heart expert, Dr Simon Swift, and refused to make the MVD protocol a breeding guideline this past year. Their one concession was to at last require a cardiologist certify the heart status of older heart clear dogs listed in the 'healthy hearts' roster on the website. As Dr Swift pointed out, in a decade, the club breeders have been so lax in following MVD guidelines as is, that their rates of affectedness for early onset MVD in the dogs they breed has altered not one iota. The Irish Club does not promote or encourage its breeders follow the MVD protocol either.
There are board members and individual breeders who are very good advocates for stronger health stances in all these clubs, some of them people I know personally and admire for their ongoing attempts to change such things, but sadly the overall hierarchy seems not to be interested in taking what many would consider basic steps to improving the health of their own breed.
Only the Swedish Club incidentally requires breeders follow the heart protocol (more or less) and have dogs cardiologist cleared. Other health clearances are also *required* in Sweden.
If you want to contact the US clubs, here are the contacts at local and national level.
ACKCSC:
http://ackcsc.org/contacts.htm
CKCSC:
http://www.ckcsc.org/ckcsc/ckcsc_inc.nsf/Founded-1954/nationalbod.html
The Swedish protocol:
BREEDING RULES FOR CAVALIER KING CHARLES SPANIEL
A dog or bitch must be at least 24 months of age before being used for breeding
A dog or bitch must have a clear Heart certificate. The certificate must have been issued within 8 months prior to the date of mating. The minimum age at which an official Heart certificate can be issued is 24 months. All heart testing of younger stock shall be regarded as unofficial and the results registered as preliminary.
A dog or bitch must not be used for breeding where its Sire or Dam has developed a murmur before the age of 4 years Where one or both parents do not have a clear Heart certificate at a minimum age of 4 years, the progeny must be at least 4 years of age and have a clear Heart certificate before being used for breeding.
DEFINITIONS:
An application for exemption can be made to the SCK where the Sire or Dam of a bitch does not hold a clear Heart certificate at the age of 4 years. The progeny of a bitch granted such exemption, are prohibited from breeding until the bitch is at least 4 years of age and has a clear Heart certificate.
All progeny of a dog or bitch that has developed a murmur before the age of 4 years are prohibited from breeding. Where a dog or bitch receives a clear Heart certificate after being diagnosed with a murmur, the progeny may then be used for breeding. The change of diagnosis, procedure must comply with SCK rules.
Litters bred contrary to SCKCS/SKC rules, will be registered by the SKC but are prohibited from breeding.
Continuous evaluation and monitoring will be carried out by the SKC and SCKCS. All Heart certificates must be issued by a registered Cardiologist in accordance with a procedure approved by the SKC.
Before being used for breeding, a dog or bitch must also have a clear Eye-certificate and a clear Patella-certificate. These certificates are recommended by the SCKCS. SCKCS also recommends that all stock used for breeding, continue to be heart tested annually until the age of 7 years, even if they no longer are bred from.