Mongrel

A mongrel, mutt, or mixed-breed dog is any dog which does not belong to one officially recognized breed. While such terms may refer to all dogs of mixed breeds, the terms "dog crossbreed" and "designer dog" specifically refer to mixed-breed dogs which are intentionally bred. Mixed-breed dogs may have ancestries that include any combination of purebred dogs and other mongrels. Excluding designer dogs, mixed-breed dogs are generally considered less financially valuable than purebred dogs. Mixed-breed dogs are thought to be less susceptible to the genetic health problems associated with inbreeding (following the concept of heterosis or "hybrid vigor"). Estimates place the population of mixed-breed dogs at 150 million animals worldwide.