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A mutt with a heavy, counter-shaded winter coat Poligraf Poligrafovich.JPG
A mutt with a heavy, counter-shaded winter coat
Australian Shepherd-Border Collie mixed-breed dog Heterochromia dog sideways.jpg
Australian Shepherd-Border Collie mixed-breed dog
Although these mongrels are littermates of an Australian Shepherd mother, they look quite different and neither exactly resembles that breed. DogsMixedBreedlittermates.jpg
Although these mongrels are littermates of an Australian Shepherd mother, they look quite different and neither exactly resembles that breed.

A mongrel, mutt or mixed-breed dog is a dog that does not belong to one officially recognized breed and is not the result of intentional breeding. Estimates place their numbers at 150 million animals worldwide. [1] Although the term "mixed-breed dog" is preferred by some, many mongrels have no known purebred ancestors. Technically, crossbreed dogs, and "designer dogs" while also a mix of breeds, differ from mongrels in being intentionally bred. Although mongrels are viewed as of less commercial value than intentionally bred dogs, they are thought to be less susceptible to genetic health problems associated with inbreeding (based on the theory of heterosis), and have enthusiasts and defenders who prefer them to intentionally bred dogs.


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.


Crossbreed vs. mongrel

In the United States, the term "mixed-breed" is a favored synonym over "mongrel" among individuals who wish to avoid negative connotations associated with the latter term. [2] The implication that such dogs must be a mix of defined breeds may stem from an inverted understanding of the origins of dog breeds. Purebred dogs 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. [3] Therefore, among some experts and fans of such dogs, "mongrel" is still the preferred term. [4] [5] [6] [7]

Dog crossbreeds, sometimes called "designer dogs", also are not members of a single recognized breed. Unlike mixed-breeds, however, crossbreed 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 the planned intervention of humans.

Regional and slang terms

The words cur, [8] tyke, [9] mutt, and mongrel [10] 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 [11] 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 the 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 Trinidad and Tobago, these mixed dogs are referred to as pot hounds (pothong). In Serbia, a 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 Rico, they are known as satos ; in Venezuela they are called yusos or cacris, the latter being a contraction of the words callejero criollo (literally, street creole, as street dogs are usually mongrels); and in Chile and 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 disease called scabies. 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.

Determining ancestry

This Golden Shepherd has more average mongrel traits than either parent MuttShepherdRetriever 72.jpg
This Golden Shepherd has more average mongrel traits than either parent

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 [12] 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. [13] [14]

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 a common ancestry with the St. John's water dog – a now-extinct naturally occurring dog landrace from the island of Newfoundland.


The theory of hybrid vigor suggests that as a group, dogs of varied ancestry will be generally healthier than their purebred counterparts. In purebred dogs, intentionally breeding dogs of very similar appearance over several generations produces animals that carry many of the same alleles, some of which are detrimental. If the founding population for the breed was small, then the genetic diversity of that particular breed may be small for quite some time. In essence, when humans select certain dogs for new breeds, they artificially isolate that group of genes and cause more copies of that gene to be made than might have otherwise occurred in nature. Initially, the population will be more fragile because of the lack of genetic diversity. If the dog breed is popular, and the line continues, over hundreds of years diversity will increase due to mutations and occasional out-breeding; like an island with a few new birds—they will diversify. This is why some of the very "old" breeds are more stable. The problem is when certain traits found in the breed standard are associated with genetic disorders. Then, the artificial selective force favors the duplication of the genetic disorder, because it comes with a desired physical trait. [15] [16] The genetic health of hybrids tends to be higher. [17] Healthy traits have been lost in many purebred dog lines because many breeders of showdogs are more interested in conformation – the physical attributes of the dogs in relation to the breed standard – than in the health and working temperament for which the dog was originally bred. [18]

Populations are particularly vulnerable when the dogs bred are closely related. Inbreeding among purebreds has exposed various genetic health problems not always readily apparent in less uniform populations. Mixed-breed dogs are more genetically diverse due to the more haphazard nature of their parents' mating. However, "haphazard" is not the same as "random" to a geneticist. The offspring of such matings might be less likely to express certain genetic disorders because there might be a decreased chance that both parents carry the same detrimental recessive alleles, but some deleterious recessives occur across many seemingly unrelated breeds, and therefore merely mixing breeds is no guarantee of genetic health. Also, when two poor specimens are bred, the offspring could inherit the worst traits of both parents. This is commonly seen in dogs that came from puppy mills. [19]

Several studies have shown that mixed-breed dogs have a health advantage over purebred dogs. A German study finds that "Mongrels require less veterinary treatment". [20] Studies in Sweden have found that "Mongrel dogs are less prone to many diseases than the average purebred dog" [21] and, referring to death rates, “Mongrels were consistently in the low risk category”. [22] Data from Denmark also suggest that mixed breeds have higher longevity on average compared to purebreds. [23] A British study showed similar results, but a few breeds (notably Jack Russell Terriers, Miniature Poodles and Whippets) lived longer than mixed breeds. [24]

In one landmark study, the effect of breed on longevity in the pet dog was analyzed using mortality data from 23,535 pet dogs. The data were obtained from North American veterinary teaching hospitals. The median age at death was determined for purebred and mixed-breed dogs of different body weights. Within each body weight category, the median age at death was lower for purebred dogs compared with mixed-breed dogs. The median age at death was "8.5 years for all mixed breed dogs, and 6.7 years for all pure breed dogs" in the study. [25]

In 2013, a study found that mixed breeds live on average 1.2 years longer than purebreds, and that increasing body weight was negatively correlated with longevity (i.e. the heavier the dog, the less its lifespan). [26] Another study published in 2019 confirmed this 1.2 year difference in lifespan for mixed-breed dogs, and further demonstrated negative impacts of recent inbreeding and benefits of occasional outcrossing for lifespan in individual dogs. [27]


Mongrel dogs can be divided roughly into types:

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 Pekeapoo. Another trendy cross is the Goldendoodle, a cross between a Standard Poodle and a Golden Retriever.

In dog sports

A mixed-breed dog demonstrates dog agility MixedBreedAgilityTunnel wb.jpg
A mixed-breed dog demonstrates dog agility

Until the early 1980s, mixed-breed dogs were usually excluded from obedience and other dog sport competitions. However, starting with the American Mixed Breed Obedience Registry (AMBOR) and the Mixed Breed Dog Clubs of America (MBDCA), which created obedience venues in which mixed-breed dogs could compete, more opportunities have opened up for all dogs in all dog sports. Most dog agility and flyball organizations have always allowed mixed-breed dogs to compete. Today, mixed-breeds have proved their worth in many performance sports. In conformation shows, where dogs' conformation to a breed standard is evaluated, mixed-breed dogs normally cannot compete. For purebred dogs, their physical characteristics are judged against a single breed standard. Mixed-breed dogs, however, are difficult to classify except according to height; there is tremendous variation in physical traits such as coat, skeletal structure, gait, ear set, eye shape and color, and so on. When conformation standards are applied to mixed-breed dogs, such as in events run by the MBDCA, the standards are usually general traits of health, soundness, symmetry, and personality. The Kennel Club (U.K.) operates a show called Scruffts (a name derived from its prestigious Crufts show) open only to mixed-breeds in which dogs are judged on character, health, and temperament. Some kennel clubs, whose purpose is to promote purebred dogs, still exclude mixed-breeds from their performance events. The AKC and the FCI are two such prominent organizations. While the AKC does allow mixed-breed dogs to earn their Canine Good Citizen award, mixed-breed dogs are not permitted to enter AKC "all breed" events, though through their "Canine Partners" program, mixed-breed dogs can be registered to compete in AKC Agility, Obedience, and Rally events.

Health studies

Studies that have been done in the area of health show that mixed-breeds on average are both healthier and longer-lived than their purebred relations. This is because current accepted breeding practices within the pedigreed dog community result in a reduction in genetic diversity, and can result in physical characteristics that lead to health issues. [28]

Studies have shown that crossbreed dogs have a number of desirable reproductive traits. Scott and Fuller found that crossbreed dogs were superior mothers compared to purebred mothers, producing more milk and giving better care. These advantages led to a decreased mortality in the offspring of crossbreed dogs. [29]

See also

Related Research Articles

Basenji Dog breed

The Basenji is a breed of hunting dog. It was bred from stock that originated in central Africa. Most of the major kennel clubs in the English-speaking world place the breed in the hound group, specifically in the sighthound type. The Fédération Cynologique Internationale places the breed in its group five, and the United Kennel Club places the breed in its Sighthound and pariah group.

Whippet Dog breed resembling a small Greyhound

The Whippet is a dog breed of medium size. They are a sighthound breed that originated in England, where they descended from Greyhounds. Whippets today still strongly resemble a smaller Greyhound. Part of the Hound group, Whippets have relatively few health problems other than arrhythmia. Whippets also participate in dog sports such as lure coursing, agility, dock diving and flyball. The name is derived from an early 17th-century word, now obsolete, meaning "to move briskly".

Dog breed Group of closely related and visibly similar domestic dogs

A dog breed is a particular strain or dog type that was purposefully bred by humans to perform specific tasks, such as herding, hunting, and guarding. When distinguishing breed from type, the rule of thumb is that a breed always "breeds true". Dogs are the most variable mammal on earth, with artificial selection producing around 450 globally recognized dog breeds. These breeds possess distinct traits related to morphology, which include body size, skull shape, tail phenotype, fur type, and coat colour. Their behavioural traits include guarding, herding, and hunting, and personality traits such as hypersocial behavior, boldness, and aggression. Most breeds were derived from small numbers of founders within the last 200 years. As a result, today dogs are the most abundant carnivore species and are dispersed around the world.

American Kennel Club

The American Kennel Club (AKC) is a registry of purebred dog pedigrees in the United States. In addition to maintaining its pedigree registry, this kennel club also promotes and sanctions events for purebred dogs, including the Westminster Kennel Club Dog Show, an annual event which predates the official forming of the AKC, the National Dog Show and the AKC National Championship. The AKC is not affiliated with the Fédération Cynologique Internationale.

Shetland Sheepdog Dog breed

The Shetland Sheepdog, often known as the Sheltie, is a breed of herding dog that originated in the Shetland Islands of Scotland. The original name was Shetland Collie, but this caused controversy among the Rough Collie breeders of the time, so the breed's name was formally changed. This hard-working small dog is intelligent, vocal, excitable and willing to please. They are incredibly loyal to their owners to the point where they are often referred to as "shadows" due to their attachment to family. This breed was formally recognized by The Kennel Club (UK) in 1909.

Bullmastiff Dog breed

The Bullmastiff is a large-sized breed of domestic dog, with a solid build and a short muzzle. The Bullmastiff is mastiff type dog, and was originally developed by 19th-century gamekeepers to guard estates. The breed was created by crossing the English Mastiff with the now extinct Old English Bulldog. It was recognized as a purebred dog by the English Kennel Club in 1924.

Staffordshire Bull Terrier Dog breed

The Staffordshire Bull Terrier is a British breed of short-haired terrier of medium size. It originated in the city of Birmingham and in the Black Country of Staffordshire, it is the direct descendant of the Bull and terrier which was itself bred from cross-breeding the Old English Bulldog and the Old English Terrier. The breed’s ancestors were bred primarily for the blood sports of dog fighting and rat-baiting.

Boxer (dog) Dog breed

The Boxer is a medium to large, short-haired breed of dog, developed in Germany. The coat is smooth and tight-fitting; colors are fawn, brindled, or white, with or without white markings. Boxers are brachycephalic, have a square muzzle, mandibular prognathism, very strong jaws, and a powerful bite ideal for hanging on to large prey. The Boxer was bred from the Old English Bulldog and the now extinct Bullenbeisser which became extinct by crossbreeding rather than by a decadence of the breed. The Boxer is part of the Molosser group. This group is a category of solidly built, large dog breeds that all descend from the same common ancestor, the large shepherd dog known as a Molossus. The Boxer is a member of the Working Group.

Alaskan Malamute Dog breed

The Alaskan Malamute is a large breed of dog that was originally bred for their strength and endurance to haul heavy freight as a sled dog and hound. They are similar to other arctic, husky, and spitz breeds such as the Greenland Dog, Canadian Eskimo Dog, the Siberian Husky, and the Samoyed.

Chinook (dog) Dog breed

The Chinook is a breed of sled dog, developed in the state of New Hampshire during the early 20th century. The Chinook is New Hampshire's official state dog.

<i>Australian National Kennel Council</i>

The Australian National Kennel Council (ANKC) is the coordinating kennel club of Australia. The ANKC is a member of the Fédération Cynologique Internationale.

Dog breeding

Dog breeding is the practice of mating selected dogs with the intention of maintaining or producing specific qualities and characteristics. When dogs reproduce without such human intervention, their offspring's characteristics are determined by natural selection, while "dog breeding" refers specifically to the artificial selection of dogs, in which dogs are intentionally bred by their owners. Breeding relies on the science of genetics, hence a breeder who is knowledgeable on canine genetics, health, and the intended purpose of the dogs attempts to breed suitable dogs.

Labradoodle Dog breed

A Labradoodle is a crossbreed dog created by crossing the Labrador Retriever and the Standard, Miniature, or Toy poodle. The term first appeared in 1955, but was not initially popular. Labradoodles are considered a good choice for people with canine dander allergies, since some have the same hypoallergenic coat as their poodle ancestors.

Dog crossbreed Dog type

Dog crossbreeds, sometimes called designer dogs, are dogs which have been intentionally bred from two or more recognized dog breeds. They are not dogs with no purebred ancestors, but are not otherwise recognised as breeds in their own right, and do not necessarily breed true.

Purebreds, also called purebreeds, are cultivated varieties or cultivars of an animal species, achieved through the process of selective breeding. When the lineage of a purebred animal is recorded, that animal is said to be pedigreed.


A crossbreed is an organism with purebred parents of two different breeds, varieties, or populations. Crossbreeding, sometimes called "designer crossbreeding", is the process of breeding such an organism, often with the intention to create offspring that share the traits of both parent lineages, or producing an organism with hybrid vigor. While crossbreeding is used to maintain health and viability of organisms, irresponsible crossbreeding can also produce organisms of inferior quality or dilute a purebred gene pool to the point of extinction of a given breed of organism.

Purebred dog

A purebred dog typically refers to a dog of a modern dog breed with a documented pedigree in a stud book and may be registered with a breed club that may also be part of a national kennel club.

Dalmatian (dog) Dog breed

The Dalmatian is a breed of large-sized dog, noted for its unique white coat marked with black or liver-colored spots. Originating as a hunting dog, it was also used as a carriage dog in its early days. The origins of this breed can be traced back to Croatia and its historical region of Dalmatia. It is thought that early ancestors of the breed were certain breeds of pointers and a spotted Great Dane. Today, it is a popular family pet and many dog enthusiasts enter Dalmatians into kennel club competitions.

Popular sire effect

The popular sire effect occurs when an animal with desirable attributes is bred repeatedly. In dog breeding, a male dog that wins respected competitions becomes highly sought after, as breeders believe the sire possesses the genes necessary to produce champions. The popular sire is often bred extensively with many females. This can cause undetected, undesirable genetic traits in the stud to spread rapidly within the gene pool. It can also reduce genetic diversity by the exclusion of other males.

Purebred breeders are dog breeders that intentionally breed purebred dogs specifically to continue the lineage of certain breed characteristics in dogs by mating selected canines.


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