Crossbreeding and Backbreeding
In some registries, breeders may apply for permission to crossbreed other breeds into the line to emphasize certain traits, to keep the breed from extinction or to alleviate problems caused in the breed by inbreeding from a limited set of animals. A related preservation method is backbreeding, used by some equine and canine registries, in which crossbred individuals are mated back to purebreds to eliminate undesirable traits acquired through the crossbreeding.
Read more about this topic: Breed Registry