A hairless dog is a

dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. Do ...

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 and t ...

type. The dominant type is caused by

ectodermal dysplasia Ectodermal dysplasia (ED) is a group of genetic syndromes all deriving from abnormalities of the ectodermal structures.James, William; Berger, Timothy; Elston, Dirk (2005). ''Andrews' Diseases of the Skin: Clinical Dermatology''. (10th ed.). Sau ...

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 the ...

'' 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 Ha ...

, the

Xoloitzcuintle The Xoloitzcuintle (or Xoloitzquintle, Xoloitzcuintli, or Xolo) is one of several breeds of hairless dog. It is found in standard, intermediate, and miniature sizes. The Xolo also comes in a coated variety, totally covered in fur. Coated and hairl ...

(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 American Hairless Terrier is a breed of companion dog from the United States that was developed from naturally hairless Rat Terriers. History In 1972 a completely hairless bitch pup was whelped in a litter of purebred Rat Terriers owned by Wil ...

. The

Argentine pila dog The Argentine Pila ( es, El perro pila) is an Argentine breed of hairless dog. It is recognised by the Asociación Canina Argentina. It is one of a small number of hairless dog breeds; others include the African hairless dog, the American Hairle ...

, 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 African hairless dogs, also known as Abyssinian sand terriers, were hairless dogs from Africa. It is unknown if any examples still exist. This breed of dog, also known as the African Sand Dog, is known for being “semi-wild” meaning they tend t ...

(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. Mo ...

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 ''c ...

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

Hairless dog breeds

* Khala *

Gallery

File:Xoloitzcuintle sitting.jpg,

File:Chinese Crested Dog 600.jpg,

File:Inca Hairless Dog.JPG,

File:American Hairless Terrier.jpg,

References

Citations

Bibliography

* {{DEFAULTSORT:Hairless Dog Dog anatomy Dog types