Dog breed

A dog breed is a particular type of

First dog breeds

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 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.^[10]

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.^[11] Most modern dog breeds are the products of the controlled breeding practices of the Victorian era (1830-1900),^[12][13] 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.^[14]

Genetic evidence

The domestic dog is the first species, and the only large

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 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.^[18]

Ancient dog breeds

"Ancient breed" is a term formerly, but no longer, used for a particular group of dog breeds by the American Kennel Club.^[13][20] 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 (pure-bred breeding) have led to distinct genetic units. The study identified 9 breeds that could be represented on 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 the other European dogs despite reports of direct Scandinavian origins dating back 5,000 years.^[19]

Dog types

The spread of modern dog breeds has been difficult to resolve because many are the product of the controlled breeding practices of the Victorian era (1830–1900).^[12][13] In 2010, a study looked at 48,000 single nucleotide polymorphisms that gave a genome-wide coverage of 912 dogs representing 85 breeds.^[21]

The study found distinct genetic clusters within modern dogs that largely corresponded to

• an Asian group (
  Akita and Shar Pei
  )
• a Middle Eastern group (
  Afghan hound and Saluki
  )
• a northern group (Alaskan Malamute and Siberian Husky).^[21]

The earliest books in 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

The 2012 study found that modern breeds only emerged in 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.^[28]

Of the basal breeds, the American Eskimo Dog and Eurasier were 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 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.^[28]

Medical research

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.^[29]

Breed temperament

In 2014, 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.^[30]

Breeds

Pure breeds

In Canada, the Animal Pedigree Act lays out strict standards for the documenting of what it calls "evolving breeds".[35]^[36]

Breed standards

The

Fédération Cynologique Internationale (FCI) is neither a breed registry nor does it issue pedigrees or keep addresses for breeders.^[39] 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 the pedigrees and judges of all FCI members.^[40]

Health issues

Purebred dogs have more health problems than mongrel dogs, and require more veterinary visits,^[41] and tend to have lower longevity.^[42][43] Indeed, studies have reported lifespans that are shorter by between one and almost two years.^[44][45] Notably, dog breeds with flat faces and short noses have breathing difficulties,^[46] eye trouble and other health issues.^[47]

List of pure breeds

Refer: List of dog breeds

The Fédération Cynologique Internationale is a global organisation with 98 members and contract partners (one member per country) that recognize 354 purebreds.^[40]

Cross-breeds

A

  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.^[55][56] 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 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.

^[57][58]

Mixed-breeds

A mongrel, mixed-breed dog or mutt is a dog that does not belong to one officially recognized breed but can be a mix of two breeds and is not the result of intentional breeding.^[59]

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.^[60] 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.^[61] Therefore, among some experts and fans of such dogs, mongrel is still the preferred term.^{[62][63][64][65]}

Natural breeds

See further: Landraces

Natural breeds rose through time in response to a particular environment and in isolation from other populations of the species.^[66] This environment included humans but with little or no selective breeding by humans.^[67]

Lists

See also

• Dogs portal
• List of dog breeds
• Hypertype

References