A mongrel, mixed-breed dog or mutt,
Is a dog that is not the result of intentional breeding.  Estimates place their numbers at 150 million animals. 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.
Mixed-breed or crossbreed
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.
Mixed breed or mongrel
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.
Regional and slang terms
The words cur, tyke, mutt, and mongrel are used, sometimes in a derogatory manner. There are also regional terms for mixed-breed dogs. In the United Kingdom mongrel is the unique technical word for a mixed-breed dog. North Americans generally prefer the term mix or mixed-breed. Mutt is also commonly used (in the United States and Canada). Some American registries and dog clubs that accept mixed-breed dogs use the breed description All American.
There are also names for mixed-breeds based on geography, behavior, or food. In Hawaii, mixes are referred to as poi dogs, although they are not related to the extinct Hawaiian poi dog. In The Bahamas and Turks and Caicos Islands, the common term is potcake dogs (referring to the table scraps they are fed). In South Africa the tongue-in-cheek expression pavement special is sometimes used as a description for a mixed-breed dog. In Serbia similar expression is prekoplotski avlijaner(over-the-fence yard-dweller). In the Philippines, mixed-breed street dogs are often called askal, a Tagalog-derived contraction of asong kalye (”street dog”). In Puerto Ricothey are known as satos; in Venezuela they are called cacris, a contraction of the words callejero criollo (literally, street creole, as street dogs are usually mongrels); and in Chileand Bolivia, they are called quiltros. In Costa Rica it is common to hear the word zaguate, a term originating from a Nahuatl term, zahuatl, that refers to the scabiesdisease. In the rural southern United States, a small hunting dog is known as a feist.
Slang terms are also common. Heinz 57, Heinz, or Heinz Hound is often used for dogs of uncertain ancestry, in a playful reference to the “57 Varieties” slogan of the H. J. Heinz Company. In some countries, such as Australia, bitsa (or bitzer) is sometimes used, meaning “bits o’ this, bits o’ that”. In Brazil and the Dominican Republic, the name for mixed-breed dogs is vira-lata (trash-can tipper) because of homeless dogs who knock over trash cans to reach discarded food. In Newfoundland, a smaller mixed-breed dog is known as a cracky, hence the colloquial expression “saucy as a cracky” for someone with a sharp tongue.
Source….. Take the Test
Guessing a mixed-breed’s ancestry can be difficult even for knowledgeable dog observers, because mixed-breeds have much more genetic variation than purebreds. For example, two black mixed-breed dogs might each have recessive genes that produce a blond coat and, therefore, produce offspring looking unlike their parents.
Starting in 2007, genetic analysis has become available to the public. The companies claim their DNA-based diagnostic test can genetically determine the breed composition of mixed-breed dogs. These tests are still limited in scope because only a small number of the hundreds of dog breeds have been validated against the tests, and because the same breed in different geographical areas may have different genetic profiles. The tests do not test for breed purity, but for genetic sequences that are common to certain breeds. With a mixed-breed dog, the test is not proof of purebred ancestry, but rather an indication that those dogs share common ancestry with certain purebreds. The American Kennel Club does not recognize the use of DNA tests to determine breed.
As well, many newer dog breeds can be traced back to a common foundational breed making them difficult to separate genetically. For example, Labrador Retrievers, Flat-coated Retrievers, Chesapeake Bay Retrievers, and Newfoundland Dogs share the ancestry of the St. John’s water dog – a now extinct naturally-occurring dog breed from the island of Newfoundland
Mongrel dogs can be divided roughly into types:
- Mixes that show characteristics of two or more breeds. A mix might have some purebred ancestors, or might come from a long line of mixed-breeds. These dogs are usually identified by the breed they most resemble, such as a “Lab mix” or “Collie-Shepherd”, even if their ancestry is unknown.
- The generic pariah dog, or feral Canis lupus familiaris, where non-selective breeding has occurred over many generations. The term originally referred to the wild dogs of India, but now refers to dogs belonging to or descended from a population of wild or feral dogs. The Canaan Dog is an example of a recognized breed with pariah ancestry. Pariah dogs tend to be yellow to light brown and of medium height and weight. This may represent the appearance of the modern dog’s ancestor. DNA analysis has shown pariah dogs to have a more ancient gene pool than modern breeds.
- Functional breeds, which are purpose-bred dogs whose ancestors are not purebred, but rather are selected by their performance at a particular tasks. Examples of this are the Alaskan Husky, the Eurohound, and the Pointer/Greyhound mixes referred to as Greysters, which compete at skijoring and pulka races, particularly in Europe. Occasionally a functional breed such as this becomes accepted as a breed over time.
Purebred dogs are known by breed names given to groups of dogs that are visibly similar in most characteristics and have reliable documented descent.
But in recent years many owners and breeders of crossbreed dogs identify them — often facetiously — by invented names constructed from parts of the parents’ breed names. These are known as portmanteau names and the resulting crosses as “designer dogs.” For example, a cross between a Pekingese and a Poodle may be referred to as a Peekapoo. Another trendy cross is the Goldendoodle, a cross between a standard poodle and a golden retriever.