The principal purpose in breeding a litter should be to advance the breed in general and your “kennel” in particular. To this end, those who always use their own stud dogs on their own bitches and who repeat litters from which nothing particularly good has come, would seem to need their motives or knowledge questioning.
You should only retain a puppy if there is some indication that, as a adult, it will be better than the dam. If not, then it is a mistake to retain one simply to have one of the dam’s puppies for sentimental reasons. If the litter has been tolerable, but there is nothing that advances the breeding material of your kennel, then it is wise to sell the entire litter.
If a litter has been bred to seek to improve specific features then you must look for those features in the litter. This is not always easy. Such features like the shape of the croup will not become obvious until a puppy is quite old. Other features such as proportions, head shape and angulation may be visible to the experienced eye by 8 weeks of age.
It’s a good idea to keep notes on the development of the puppies from birth to 8 weeks of age. Body weights etc., Film recordings are useful so that an actual record exists which in time can be compared to your adult dogs. Given sensible records, a breeder will learn how to distinguish between the puppies that show promise and those which are pet quality. Selecting puppies is not an exact science, nor is it likely to become one – and there will always be puppies which end up surprising you.
Clearly you cannot predict such things as incorrect bites or missing teeth, but an experienced breeder should be able to identify those puppies in the litter that will have the correct proportions, angulations and heads.
(M B Willis – excerpt 1992)