A hairless dog is a dog with a genetic disposition for hairlessness and hair loss. There are two known types of genetic hairlessness, a dominant and a

recessive In genetics, dominance is the phenomenon of one variant ( allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant an ...

type. The dominant type is caused by ectodermal dysplasia as a result of a mutation in the ''

FOXI3 Forkead box I3 (FOXI3) is a protein that in humans is encoded by the ''FOXI3'' gene. FOXI3 is a forkhead box transcription factor that is expressed in the development of hair and teeth. One of its mutations is a dominant allele responsible for t ...

'' autosomal gene.

Dominant genes

Dogs with dominant genes for hairlessness can pass their attributes to their offspring in natural conditions; that is, not under the control of humans. Therefore, it is possible that, in some parts of the world, groups of hairless dogs came into existence without human intervention. Later in history, people developed these groups into recognized breeds. Worldwide recognized breeds at this time are the

Chinese Crested Dog The Chinese Crested Dog is a hairless breed of dog. Like most hairless dog breeds, the Chinese Crested Dog comes in three varieties, with hair, without hair and a combination of the two, which can be born in the same litter: the Powderpuff, the H ...

, the Xoloitzcuintle (Mexican Hairless Dog), the

Peruvian Inca Orchid The Peruvian Hairless Dog, Peruvian viringo, naked dog, or Chimú dog is one of several breeds of hairless dog. It is native to Peru and it is usually raised as a pet. It has been officially recognized as part of Peru's cultural heritage. ...

and the American Hairless Terrier. The Argentine pila dog, the Bolivian Hairless Dog, and the Ecuadorian Hairless Dog are not registered hairless dog breeds. Other breeds that were said to have existed in the past were the African hairless dog (also known as the Abyssinian sand terrier, Egyptian hairless dog and African elephant dog, the last being a reference to its grey skin) and the Siamese Hairless Dog. This type of genetic structure is said to be

homozygous Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Mo ...

pre-natal lethal for the dominant gene. This means that zygotes with two dominant genes cannot live. Therefore, all dominant-hairless dogs have a

heterozygous Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. ...

gene structure. This allows a homozygous recessive type to persist, which is the coated variety. For dogs where hairlessness is a dominant gene, hairless to hairless matings will on average produce 66.6% hairless and 33.3% coated puppies. For hairless to coated matings, there will be an average of 50%/50% coated to hairless ratio, while for coated to coated matings, all puppies will be coated. The Chinese Crested Dog's coated variety is called a "Powderpuff" and is a recognized type. The coated variety of the Xoloitzcuintle is recognized as a valid type for conformation showing with some registries, including the AKC. Coated varieties of the other breeds may or may not be recognized as valid varieties for

conformation show A dog show is an event where dogs are exhibited. A conformation show, also referred to as a '' breed show'', is a kind of dog show in which a judge, familiar with a specific dog breed, evaluates individual purebred dogs for how well the dogs ...

ing, depending on the breed and show or registry organization.

Hairless dog breeds

* African hairless dog * American Hairless Terrier * Argentine pila dog *

* Khala *

* Xoloitzcuintle

Gallery

File:Xoloitzcuintle sitting.jpg, Xoloitzcuintle File:Chinese Crested Dog 600.jpg,

File:Inca Hairless Dog.JPG,

File:American Hairless Terrier.jpg, American Hairless Terrier

References

Citations

Bibliography

* {{DEFAULTSORT:Hairless Dog Dog anatomy Dog types