Mixed-breed dogs

A mongrel, mixed-breed dog or mutt, is a dog that does not belong to one recognized breed and is not the result of intentional breeding. Estimates place their numbers at 150 million animals worldwide. Although the term "mixed-breed dog" is preferred by some, many mongrels have no known purebred ancestors. Furthermore, crossbreed dogs, while literally a mix of breeds, differ from mongrels in being intentionally bred. Although mongrels have at times been considered somehow lesser than intentionally bred dogs, they tend to be less susceptible to genetic health problems associated with dog breeding, and have enthusiasts and defenders who prefer them to intentionally bred dogs.

Although mongrels exhibit great variation, generations of uncontrolled breeding and environmental pressures may tend to shape them toward certain general average body types and characteristics known as landraces, some of which may be developed by people into new breeds such as the Alaskan husky.

At other times, the word "mongrel" has been applied to informally purpose-bred dogs such as curs which were created at least in part from mongrels, especially if the breed is not officially recognized.

Like mongrels/mixed breeds, crossbred dogs belong to no one recognized breed. Unlike mixed-breeds, however, crossbred dogs are often the product of artificial selection – intentionally created by humans, whereas the term "mongrel" specifically refers to dogs that develop by natural selection, without planned intervention of humans.

In the United States, the term "mixed-breed" is a favored synonym over "mongrel" among many who wish to avoid negative connotations associated with the latter term. The implication that such dogs must be a mix of defined breeds may stem from an inverted understanding of the origins of dog breeds. Pure breeds have been, for the most part, artificially created from random-bred populations by human selective breeding with the purpose of enhancing desired physical, behavioral, or temperamental characteristics. Dogs that are not purebred are not necessarily a mix of such defined breeds. Therefore, among some experts and fans of such dogs, "Mongrel" is still the preferred term.

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