Nancy - you said: The belief that mixing breeds makes for healthier or smarter is false
The below is from wikipedia - it goes along with what three different vet's have told me when I have ask them about the breeding of good quality purebred dogs:
Some dog hybrids are now being selectively bred. The term designer dogs is often used to refer to these mixes and crosses. The practice causes much controversy; opponents cite the often exorbitant prices charged for what may just be a mutt.
While the trend to produce hybrid or designer dogs is considered new it is, in fact, a continuation of the centuries-old practice of selective breeding. Basically every breed of dog is a "mutt" in the sense that every type of dog was created by interbreeding different types of dogs to produce a breed with a certain set of desirable characteristics. All dog breeds were bred for a particular purpose, usually some form of hunting, herding, or guarding. These tasks have been largely replaced by the need to produce healthy dogs with good temperaments as domestic companions or pets. Breeding two different breeds often allows the best traits of both parents to pass through.
Hybrid dogs, created by breeding two purebred dogs of different breeds (crossbred), have the advantage of heterosis, or hybrid vigor, and are often stronger and healthier than either of the parents. This advantage is lost when two hybrids are bred in the attempt to create a breed. The best way to continue taking advantage of hybrid vigor is from the breeding of two different purebred breeds.[/COLOR]