Puppies from a repeat breeding are considered littermates for this purpose. The blood samples can, of course, be stored for future use. Although progress is being made, waiting for DNA testing to become readily available is not a feasible solution to the problems of many genetic diseases. Selectively breeding away from carriers now is the only responsible action. In some instances, careful breeders have succeeded in largely eradicating some genetic disorders from their breeds.
Success depends on a number of factors.
Every puppy buyer must be encouraged to report any major illness back to the breeder. Breeders must have a clear understanding of the modes of transmission of genetic disorders that affect their breeds. A method of communication among breeders must be established. In Europe, open registries have made it possible for careful breeders to greatly reduce the number of cases of some genetic disorders. An open registry would include the names of carriers of the disease as well as the names of dogs who are clear, those who when bred to a carrier did not produce any cases of the disease in a litter of significant size.