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70-532: The Bullmastiff is an English breed of dog of mastiff type and large size, with a solid build and a short muzzle. It was developed as a guard dog in the nineteenth century by cross-breeding the English Mastiff with the now-extinct Old English Bulldog . It was recognised as a breed by The Kennel Club in 1924. The origins of the Bullmastiff are unclear. In the 18th century, in some regions of England,

140-456: A breed standard which is a written description of the ideal specimen of the breed. Other uses of the term breed when referring to dogs include pure breeds , cross-breeds , mixed breeds and natural breeds . Prior to the standardization of dog breeds, there were many different types of dogs that were defined by their own, unique functions. Many different terms were used to describe dogs, such as breed, strain, type, kind, and variety. By

210-457: A lncRNA variant in the IGF1 region arisen in wolves from northern latitudes c. 53.000 years ago and fixed by natural and subsequently by human selection. Their behavioral traits include guarding, herding, and hunting, retrieving, and scent detection. Their personality traits include hypersocial behavior, boldness, and aggression, which demonstrates the functional and behavioral diversity of dogs. As

280-456: A "school" book about hawking , hunting, fishing, and heraldry , attributed to Juliana Berners (Barnes), lists dogs of the time mainly by function: "First there is a greyhound, a bastard, a mongrel , a mastiff, a limer, a spaniel, " raches " (small-to-medium-sized scenthounds), "kennets" (small hunting dogs), terriers , "butcher's hounds", dung-heap dogs, "trundel tails" ( lapdogs ?) and prick-eared curs , and small ladies puppies that bear away

350-450: A 0.46 kg (1.0 lb) teacup poodle to a 90 kg (200 lb) giant mastiff . The skull, body, and limb proportions vary significantly between breeds, with dogs displaying more phenotypic diversity than can be found within the entire order of carnivores. These breeds possess distinct traits related to morphology, which include body size, skull shape, tail phenotype, fur type and colour. The difference in size has been attributed to

420-570: A 2010 study ( Afghan Hound , Akita , Alaskan Malamute , American Eskimo , Basenji , Canaan dog , Chow Chow , Dingo , New Guinea singing dog , Saluki , Samoyed , Shar-Pei , Siberian Husky ), plus another three: the Eurasier , Finnish Spitz and Shiba Inu . The study referred to these 16 as basal breeds, as opposed to ancient breeds, as they exhibited genetic divergence but not all of them were historically considered to be "ancient breeds". The 2012 study found that modern breeds only emerged in

490-421: 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

560-651: 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

630-616: A desired physical trait. The genetic health of hybrids tends to be higher. 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. Populations are 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

700-703: A known foundation stock may still not be recognized by some clubs as breeds. For instance, the feist is a hunting dog raised in the Southern United States for hunting small game. Feists have a consistent set of characteristics that reliably differentiate them from other dog types and breeds. However, the United Kennel Club recognizes one breed of feist, the Treeing Feist , while the American Kennel Club does not recognize any feist breed. A dog

770-464: A mix of two breeds and is not the result of intentional breeding . 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. 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

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840-491: 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 term All-American to describe mixed-breed dogs. 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

910-483: A particular environment and in isolation from other populations of the species. This environment included humans but with little or no selective breeding by humans . Mixed breed dog Crossbreed dogs, and " designer dogs ", while also a mix of breeds , differ from mongrels in being intentionally bred. 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

980-590: A result, the Bullmastiff is known as the Gamekeeper's Night Dog. The Bullmastiff was recognised as a breed by The Kennel Club in 1924. Dogs had to have a minimum of four generations of descent from Bullmastiff stock without input from either Bulldog or Mastiff; cross-bred animals could not be registered. The American Kennel Club recognised it in 1934. It was definitively accepted by the Fédération Cynologique Internationale in 1955. In 1928,

1050-561: A result, today dogs are the most abundant carnivore species and are dispersed around the world. The most striking example of this dispersal is that of the numerous modern breeds of European lineage during the Victorian era . A genetic study identified 51 regions of the dog genome which were associated with phenotype variation among breeds in the 57 traits studied, which included body, cranial, dental, and long bone shape and size. There were three quantitative trait loci that explained most of

1120-488: A select set of ancestors who had the same characteristics. Dogs of a specific breed breed true , producing young that are very similar to their parents. An individual dog is identified as a member of a breed through proof of ancestry, using genetic analysis or written records of ancestry. Without such proof, identification of a specific breed is not reliable. Such records, called stud books , may be maintained by individuals, clubs, or other organizations. Kennel clubs provide

1190-724: A sled dog is 20–25 kg (44–55 lb) based on thermo-regulation, and the ancient sled dogs were between 16–25 kg (35–55 lb). The same standard has been found in the remains of sled dogs from this region 2,000 years ago and in the modern Siberian Husky breed standard. Other dogs were larger at 30 kg (66 lb) and appear to be dogs that had been crossed with wolves and used for polar-bear hunting. Between 3,000 and 4,000 years ago greyhound -types of dogs were depicted on pottery and paintings in Egypt and Western Asia. Mastiff -type dogs were kept for guarding and hunting, and short-legged dogs were also bred. Most modern dog breeds are

1260-407: A study indicated that some breed-temperaments, such as anxiety or fear, may be linked to gene mutations. Other temperaments may be due to the legacies of 'ancient' ancestry. Groups of owners that have dogs of the same breed and have an interest in dog breeding can form national Kennel clubs . Kennel Clubs maintain breed standards , record pedigrees in a breed registry (or studbook), and issue

1330-593: Is prekoplotski avlijaner ( over-the-fence yard-dweller ). In Russia , a colloquial term дворняга (yard-dweller) is used most commonly. In the Philippines , mixed-breed street dogs are often called askal , a Tagalog -derived contraction of asong kalye (”street dog"), while in Singapore, they are known as Singapore Specials. In Puerto Rico , they are known as satos ; in Venezuela they are called yusos or cacris ,

1400-515: 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. 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

1470-475: Is a global organisation with 98 members and contract partners (one member per country) that recognize 356 purebreds. A dog crossbreed is the result of mating two different breeds. "Designer Dog" became a fad in the late 20th century. Dog crossbreeds are combinations of lineages of the domestic dog ; they are distinguished from canid hybrids , which are interspecific crosses between Canis species (wolves, coyotes, jackals, etc.). Notable canid hybrids include

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1540-731: Is a term formerly, but no longer, used for a particular group of dog breeds by the American Kennel Club. These breeds were referred to as "ancient", as opposed to modern, breeds because historically it was believed their origins dated back more than 500 years. In 2004, a study looked at the microsatellites of 414 purebred dogs representing 85 breeds. The study found that dog breeds were so genetically distinct that 99% of individual dogs could be correctly assigned to their breed based on their genotype , indicating that breeding barriers (purebred breeding) have led to distinct genetic units. The study identified 9 breeds that could be represented on

1610-451: 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. 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

1680-827: Is common in the breed. A mutation to the RHO gene is responsible. Bullmastiffs also are prone to ear infections. Dog breed A dog breed is a particular type of dog that was purposefully bred by humans to perform specific tasks, such as herding, hunting, and guarding. Dogs are the most variable mammal on Earth, with artificial selection producing upward of 360 globally recognized breeds. These breeds possess distinct traits related to morphology, which include body size and shape, tail phenotype , fur type, etc, but are only one species of dog. Their behavioral traits include guarding, herding, and hunting, and personality traits such as hyper-social behavior, boldness, and aggression. Most breeds were derived from small numbers of founders within

1750-470: 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

1820-565: Is neither a breed registry nor does it issue pedigrees or keep addresses for breeders. It is a global canine organization with member and contract partners (one member per country) that conduct international conformation shows, working/hunting/herding trials, and various other events. The results are submitted to FCI for processing, approval and international recognition. Each of the member and contract partners issue and maintain their own pedigrees and respective breed standards, and train their own judges. FCI ensures that each member mutually recognizes

1890-575: Is said to be purebred if their parents were purebred and if the dog meets the standards of the breed. The American Kennel Club allows mixed-breed dogs to be shown but under the condition the animals have been spayed or neutered, are not a wolf hybrid, and not eligible for the AKC Foundation Stock Service Program or an AKC Purebred Alternative Listing (PAL). In Canada, the Animal Pedigree Act lays out strict standards for

1960-474: The De Beers diamond mining company imported Bullmastiffs to South Africa to guard the mines. The Bullmastiff is a large dog. Bitches stand some 61–66 cm at the withers , and usually weigh 41–50 kg ; on average, dogs stand about 3 cm taller and weigh 9 kg more. The coat may be fawn, red, or brindle, in any shade; some limited white marking on the chest is allowed. The muzzle is black, becoming paler towards

2030-443: The English Mastiff and Old English Bulldog were commonly inter-bred to produce dogs suitable for guarding people and their property. By the beginning of the 20th century, this cross-breed was in widespread use as an aid to gamekeepers in the control of poaching . They were bred for strength, size and speed using a cross of the tough, heavy and aggressive 19th century Bulldog with the large, strong, less aggressive Mastiff . As

2100-423: The Fédération Cynologique Internationale ." In 2017, a study showed that 9,000 years ago the domestic dog was present at what is now Zhokhov Island , arctic north-eastern Siberia, which was connected to the mainland at that time. The dogs were selectively bred as either sled dogs or as hunting dogs, which implies that a sled dog standard and a hunting dog standard existed at that time. The optimal maximum size for

2170-484: The coydog , coywolf , dingo–dog hybrid , jackal–dog hybrid , and wolfdog .   Historically, crosses between dogs of different types were more well accepted at a time when modern purebred breeds (based on the eugenics principles) did not yet exist. Some crossbred dogs, created by breeding two purebred dogs of different breeds, may have the advantage of heterosis , or crossbreed vigor. This advantage can be progressively diluted when two crossbreeds are bred in

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2240-418: The fleas and diverse small sorts." A study in 2012 examined 49,000 single nucleotide polymorphisms that gave a genome -wide coverage of 1,375 dogs representing 35 breeds, 19 wolves, and previous published genetic signatures of other breeds, giving a total of 121 breeds covered. The study found a deep genetic split between old-world and new-world wolves, and confirmed the genetic divergence of 13 breeds from

2310-500: The 19th century and that claims of their antiquity are based on little or no historical or empirical evidence. The study indicated that throughout history, global dog populations experienced numerous episodes of diversification and homogenization, with each round further reducing the power of genetic data derived from modern breeds to help infer their early history. Of the basal breeds, the American Eskimo Dog and Eurasier were

2380-449: The English language to mention numbers of dog types are from the "Cynegetica" (hunting literature), namely, The Art of Venery (1327) by Twiti (Twici), a treatise that describes hunting with the limer (a leashed bloodhound type); the pack of running hounds , which included barcelets and brachetz (both scent hounds ); and the sighthound and greyhound . More significant in recording

2450-426: The United States, the term mixed-breed is a favored synonym over mongrel among people 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. Purebred dogs have been, for the most part, artificially created from random-bred populations by human selective breeding with

2520-445: The attempt to create a breed, narrowing the gene pool. The best way to continue taking advantage of crossbreed vigor is from the breeding of dogs of purebred ancestry, as this vigor is typically seen only in the first generation cross of two purebred animals of separate breeds, thus taking advantage of genetic diversity . A mongrel, mixed-breed dog or mutt is a dog that does not belong to one officially recognized breed but can be

2590-548: The branches of a phylogenetic tree which grouped together with strong statistical support and could be separated from the other breeds with a modern European origin. These 9 breeds had been referred to as "ancient breeds". The study found that the Pharaoh Hound and Ibizan Hound were not as old as once believed; rather, they had been recreated from combinations of other breeds, and that the Norwegian Elkhound grouped with

2660-882: The breed club to be unacceptable (called faults ). In addition, most breed standards include a historical section, describing the place of origin and the original work done by the breed or its ancestor types . Dogs with a breed standard may be accepted into one or more of the major registries ( kennel clubs ) of dog breeds, including The Kennel Club (1873, UK), American Kennel Club (1884), New Zealand Kennel Club (1886), Canadian Kennel Club (1888), United Kennel Club (1898), United Kennel Clubs International (UCI, Germany 1976), Australian National Kennel Council (1958), and other national breed registries. Recognized dog breeds are classified by groups , such as Hound, Terrier, Working, Herding, Sporting, Non-Sporting, Toy and Miscellaneous; some groups may be further subdivided by some registries. Fédération Cynologique Internationale (FCI)

2730-426: The breed is not officially recognized. 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. Estimates place the prevalence of mongrels at 150 million animals worldwide. In

2800-498: The breeding, exhibiting and judging of pure-bred dogs. It now has 99 member countries. According to BigThink , over 40% of the world’s dog breeds come from the United Kingdom , France and Germany . It states: " Great Britain and France are the ground zero of dog fancying, with 57 registered breeds each. Germany is not far behind, with 47 breeds. These three countries alone represent more than 40% of all dog breeds recognized by

2870-461: The documenting of what it calls "evolving breeds". The breed standard for each breed of dog is a detailed description of the appearance and behaviour of an idealized dog of that breed. Included in the breed standard description are externally observable aspects of appearance and behaviour that are considered by the breed club to be the most important for the breed, and externally observable details of appearance or temperament that are considered by

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2940-556: The dog–wolf genetic divergence are not known. Dogs are the most variable mammal on earth with around 450 globally recognized dog breeds. In the Victorian era , directed human selection developed the modern dog breeds, which resulted in a vast range of phenotypes. Most breeds were derived from small numbers of founders within the last 200 years, and since then dogs have undergone rapid phenotypic change and were formed into today's modern breeds due to artificial selection imposed by humans. These breeds can vary in size and weight from

3010-504: The end of the Victorian era, society had changed and so did the role of dogs. The form was given a more prominent role than function. Different types or breeds of dog were being developed by breeders who wanted to define specific characteristics and desirable features in their dogs. Driven by dog shows and the groups that hosted them, the term dog breed took on an entirely new meaning. Dog show competitions included best-in-breed winners, and

3080-509: 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

3150-573: The eyes. The Bullmastiff is brachycephalic , flat-faced and short-muzzled, but this does not affect its breathing. A 2024 UK study found a life expectancy of 10.2 years for the breed compared to an average of 12.7 for purebreeds and 12 for crossbreeds . Health concerns within the breed include hip and elbow dysplasia, progressive retinal atrophy, bloat, and cancer, with a relatively high incidence of lymphoma and mast cell tumours. Bullmastiffs are prone to certain hereditary diseases, including: An autosomal dominant form of progressive retinal atrophy

3220-429: The lack of genetic diversity. If the dog breed is popular, and the line continues, over hundreds of years diversity increases due to mutations and occasional out-breeding. This is why some of the very old breeds are more stable. One issue is when certain traits found in the breed standard are associated with genetic disorders. The artificial selective force favors the duplication of the genetic disorder because it comes with

3290-437: The last 200 years. As a result of their adaptability to many environments and breedability for human needs, today dogs are the most abundant carnivore species and are dispersed around the world. A dog breed will consistently produce the physical traits, movement and temperament that were developed over decades of selective breeding. For each breed they recognize, kennel clubs and breed registries usually maintain and publish

3360-446: 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

3430-508: The low risk category". Data from Denmark also suggest that mixed breeds have greater longevity on average compared to purebreds. A British study showed similar results, but a few breeds (notably Jack Russell Terriers , Miniature Poodles and Whippets ) lived longer than mixed breeds. In one 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

3500-454: The modern breeds because the genetic heritage of the modern breeds has become blurred due to admixture, and the basal breeds have mostly avoided admixture with them due to geographic or cultural barriers. As dogs are a subspecies but their breeds are distinct genetic units, and because only certain breeds share the same type of cancers as humans, the differences in the genes of different breeds may be useful in human medical research. In 2014,

3570-432: The more haphazard nature of their parents' mating. 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. When two poor specimens are bred,

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3640-416: 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. Natural breeds rose through time in response to

3710-523: The offspring could inherit the worst traits of both parents. This is commonly seen in dogs that came from puppy mills . 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". Studies in Sweden have found that "Mongrel dogs are less prone to many diseases than the average purebred dog" and, when referring to death rates, that "mongrels were consistently in

3780-458: The other European dogs despite reports of direct Scandinavian origins dating back 5,000 years. Dog types are broad categories of dogs based on form, function or style of work, lineage, or appearance. In contrast, modern dog breeds are particular breed standards, sharing a common set of heritable characteristics, determined by the kennel club that recognizes the breed. The spread of modern dog breeds has been difficult to resolve because many are

3850-441: The pedigrees and judges of all FCI members. Purebred dogs have more health problems than mongrel dogs, and require more veterinary visits, and tend to have lower longevity. Indeed, studies have reported lifespans that are shorter by between one and almost two years. Notably, dog breeds with flat faces and short noses have breathing difficulties, eye trouble and other health issues. The Fédération Cynologique Internationale

3920-412: The phenotype variation. Indicators of recent selection were shown by many of the 51 genomic regions that were associated with traits that define a breed, which include body size, coat characteristics, and ear floppiness. Wolf Shar Pei Shiba Inu Chow Chow Akita Inu Basenji Siberian Husky Alaskan Malamute Afghan Hound Saluki other breeds in the study "Ancient breed"

3990-423: 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. 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

4060-598: The product of the controlled breeding practices of the Victorian era (1830–1900). In 2010, a study looked at 48,000  single nucleotide polymorphisms that gave a genome -wide coverage of 912 dogs representing 85 breeds. The study found distinct genetic clusters within modern dogs that largely corresponded to phenotype or function. These included spitz-breeds, toy dogs, spaniels, Mastiff-like breeds, small terriers, retrievers, herding dogs, scent-hounds, and sight-hounds. There were 17 breeds that conflicted with phenotype or function and these were thought to be

4130-501: The products of the controlled breeding practices of the Victorian era (1830-1900), and the accurate documenting of pedigrees with the establishment of the English Kennel Club in 1873 in imitation of other stud book registries for cattle and horses. The domestic dog is the first species, and the only large carnivore , to have been domesticated. The first dogs were certainly wolflike, but the phenotypic changes that coincided with

4200-470: The purebreds were winning. Breed standards are the reason the breed came to be, and with those standards are key features, including form, function and fitness for purpose. The Kennel Club in the UK was founded in 1873, and was the world's first national kennel club and breed registry. The International Canine Federation was founded in 1911 as a worldwide organization. Its objective is to bring global uniformity to

4270-418: 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. Dog crossbreeds , sometimes called designer dogs , also are not members of a single recognized breed. Unlike mixed-breeds, crossbreed dogs are often

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4340-534: The recognition of distinct dog breeds, but there are many independent clubs with differing, and sometimes inconsistent standards and they need not apply scientific standards. Four varieties of the Belgian Shepherd Dog are recognised as four distinct breeds by the New Zealand Kennel Club . Further, some groups of dogs which clearly share a persistent set of characteristics and documented descent from

4410-633: The result of crossing some of the other phenotypes. As in a 2004 study that found 9 'ancient breeds' to be genetically divergent, the study found 13 breeds that were genetically divergent from the modern breeds: the Basenji , Saluki , Afghan hound , Samoyed , Canaan dog , New Guinea singing dog , dingo , Chow Chow , Chinese Shar Pei , Akita , Alaskan malamute , Siberian husky and American Eskimo dog . The study found that there were three well-supported groups that were highly divergent and distinct from modern domestic dogs. The earliest books in

4480-455: The rules for conformation dog shows and trials and accreditation of judges. They often serve as registries , which are lists of adult purebred dogs and lists of litters of puppies born to purebred parents. A dog breed is represented by a sufficient number of individuals to stably transfer its specific characteristics over generations. Dogs of same breed have similar characteristics of appearance and behavior, primarily because they come from

4550-429: 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. 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. The population is initially more fragile because of

4620-474: 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. Many newer dog breeds can be traced back to

4690-542: The use and description of various dog types is The Master of Game (circa 1406) by Edward of York , a treatise that describes dogs and their work, such as the alaunt , greyhound, pack scent hounds, spaniel , and mastiff , used by the privileged and wealthy for hunting purposes. The Master of Game is a combination of the earlier Art of Venery and the French hunting treatise Livre de Chasse by Gaston Phoebus (circa 1387). The Book of Saint Albans , published in 1486,

4760-478: The very recent product of cross-breeding other basal breeds. Most basal breeds have hybridized with other lineages in the past. If those other lineages were other basal breeds then a basal genetic signature remains. The combination of introgression and past population bottlenecks suggested that basal breeds have little or no genetic connections to their ancestral populations and that their genetic distinctiveness does not signify ancient heritage. They are distinctive from

4830-436: 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. In 2013, a study found that mixed breeds live on average 1.2 years longer than purebreds, and that increasing body weight

4900-490: Was negatively correlated with longevity (i.e. the heavier the dog, the shorter its lifespan). 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. 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

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