Charlotte, I understand your points but unfortunately it's not as simple as all that. If breeders did not in any way breed dogs who have a genetic predispostion for certain illnesses there would be no dogs. And while I agree that probably most breeders who sell their pups for a profit do not know what illnesses occur once the pups leave their doors, you have to realize that most responsible breeders do not sell their pups for a profit. You also have to realize that most pet buyers do not test their pups for heart conditions, and do not have autopsies performed, so the dog may die suddenly and it could be blamed on a bee sting, or poisioning, or heat stroke, or old age, or whatever. (And even if the dog did die of these things, it might have had a heart condition that was asymptomatic, which an autopsy if performed might reveal.)
Once you get past that, a responsible breeder *does* know as much about the health of the pups as they can, because they keep in touch with the owner throughout the life of the puppy. This type of information is vital to their breeding program. They also do health testing on the parents, so instead of telling you there are no health problems in their lines, they can *show* you that the parents have cleared the recommend health testing. There is a world of difference between the two.
Jicksies, do you know which heart disease the pup succumbed to? Sudden death occurs in both Aortic Stenosis and Boxer Cardiomyopathy. The problem is that parents who were cleared of AS can produce affected pups, and BCM is often a late-onset condition so a dog that has low VPCs at breeding time may have several hundred or thousand by the time he's 7.
I do have to say, though, that you will not find a dog in North America that does not have a close relative with one or the other conditions. It is widespread throughout the breed. The solution is not to stop breeding all dogs who are affected or whose littermates/half-siblings/etc. are affected, but to breed unaffected or at the most, the least-affected dogs (i.e., only breed dogs with grade 1 or 0 murmur, only breed dogs with less than a certain number of VPCs (that number has not been identified yet, btw), etc.)
I will probably get flak for this, myself, but IMO if Booder passes his Doppler after age 2 and is Holtered with little to no VPCs, you could consider breeding him, provided the bitch has also been screened. (And provided they've both passed hips, thyroid, brucellosis.) I'd certainly let any bitch owners know that a sibling from another litter had a heart condition, but as I said you are not going to find a dog from totally clear lines, so if Booder is unaffected removing him from the breeding pool could be detrimental to the breed in the long run. You might want to take it further and only breed him to bitches that don't have littermates with one of the conditions or that haven't produced pups with one of the conditions.
I would say that Booder's sire and dam should not be bred to each other again, nor should they be bred to other dogs that have produced a problem. (I realize that's not your call to make, but someday you might be in a similar situation.)