Every breeder of domestic animals with a closed studbook should read this, all of it. Most important is the section the writer, Jeffrey Bragg, calls Principles for the Breeder.(MANY thanks to Daniela Imre).
"The great majority of dog breeds have been bred within a completely closed studbook for sixty to a hundred years or longer, with little or no fresh genetic input throughout the entire period from breed foundation to the present. In most cases the stud book was opened for a year or two, a small number of founders, often closely related to one another, were registered, and the stud book was then closed. Thereafter, only dogs descended from the founders could be registered. And for those sixty to a hundred or more years, artificial selection, random drift, bottlenecking and other forms of attrition took their toll of whatever genetic diversity was present in the founder group. It is exactly as though a bank account had been established with a single initial deposit (the genetic diversity of the founders), with no further deposits permitted; meanwhile bank fees and direct debits (diversity losses from drift, selection, etc.) chiselled away at the balance. It is a sure and certain recipe for bankruptcy.
"Similarly, many individual bloodlines have been treated in exactly the same way, bred in relative genetic isolation from other bloodlines -- except that in this case additional deposits are at least allowed, in the form of bloodline outcrosses. Therefore each breeder probably ought to consider the desirability of locating and using a true outcross within his or her own breed (unrelated to one's own stock for at least ten to fifteen generations) at least once and to integrate the resulting progeny into one's kennel bloodline.
"If there is any possibility whatsoever to import unrelated stock from a breed's country of origin, one ought seriously to consider doing just that. This is mainly possible in the case of landrace breeds, in which an autochthonous regional population remains in the country of origin, independent of exported stock that may have become a registered breed in other countries. Examples of such situations would be the population of desert-bred coursing sighthounds in the Near East, relative to the Saluki breed in Europe and North America, or the relict populations of autochthonous arctic spitz-type sled dogs relative to the modern Siberian Husky, Alaskan Malamute, Samoyed, et al.
"It would be difficult to overestimate the genetic value of a single import animal, unrelated to the registered breed population for scores of generations but stemming from exactly the same fountainhead. This I would term the Holy Grail of the diversity breeder -- the ideal controlled-outcross situation in which an immediate significant increase in healthy genetic diversity may be obtained at little to no cost in terms of breed type and purpose. (That the Canadian Kennel Club rejected this option for the Siberian Husky in 1994 demonstrates, I believe, the true extent to which the umbrella all-breed registries represent an obstacle to genetic health and true breed welfare and improvement.)"
Are you listening, AKC? Saluki Club?
Oh right, all those "Holy Grail" dogs are... mongrels.