The traditional all-breed national dog registries such as A.K.C. and C.K.C. have for the last half-century or so gone about their work of pedigree record-keeping in a rather extreme way that has drastic effects on canine genetic health. When a breed is first recognised and registered with one of these organisations, a "stud book" is opened; the term is taken from the equine fancy and means simply a list of breeding stock, of sires, dams and their progeny.

Their usual practice is to "open the stud book" on a breed for a limited period of time, during which various animals of the breed will be "registered," that is to say, their vital data (sex, date of birth, colour and markings, name of the breeder and his place of residence, and pedigree -- the names of his parents, grandparents and great-grandparents) are recorded in a list or registry of breeding stock. The animals whose data are thus recorded are then referred to as "foundation stock" or founders of that particular breed. Usually the stud book is not opened for very long; the period may be less than a year, and quite often there are various requirements or restrictions as to what animals will be accepted as foundation stock. An inspection of some kind is frequently part of the process.

Once the registry organisation deems that a sufficient number of founders have been recorded, the stud book is then closed permanently. That means that no further founders will be entertained by the registry, and that from that point forward any and all animals of that breed must be descended from the founders already recorded, or else from an equivalent founder group from another stud book registry that has been specifically "recognised" by the organisation in question.

The most significant effect of this procedure (which is not necessarily the case in other livestock species) is to ensure that there is a marked founder effect in all dog breeds, and that there is a high level of forced inbreeding not just in the formative years of the breed but for as long as the registry endures. It is not usual for a stud book registry ever to be re-opened. Between founder effect and inbreeding, then, the very structure inherent in the closed stud books of national all-breed registries is such that genetic disease soon becomes a major problem, hardiness, longevity and reproductive viability suffer, and the word "purebbred" becomes synonymous with "sickly."