Characteristics and Symptoms
Hairlessness American Hairless Terrier type is an inherited trait specific for this breed and caused by a breed specific mutation. Generally, worldwide recognized hairless dog breeds are the Chinese crested dog, the Mexican hairless dog and the Peruvian hairless dog. Mexican hairless dog is also known as the Xoloitzcuintli, and it was considered sacred by the Aztecs. In these breeds the hairless phenotype is classified as canine ectodermal dysplasia (CED) and is caused by the same mutation. Unlike in other hairless dog breeds, hairlessness in American Hairless Terrier is a recessive mutation and is not lethal when animal is homozygote for the mutation. Also, AHT are generally healthy dogs born with fuzzy coat which is lost within first few months after birth.
The predecessor of the AHT is the rat terrier, which occasionally has hairless puppies in the litter. By directed breeding programme a true hairless phenotype was achieved, resulting in new breed today known as the American Hairless Terrier. The AHT is the newest AKC-recognized breed, and has official breed status since 2016.
Hairlessness American Hairless Terrier Type Genetics
Hairlessness American Hairless Terrier type is caused by a mutation of SGK3 gene located on canine chromosome 29. The disorder is inherited in an autosomal recessive pattern of inheritance, which means two causative genes need to be present in order for the puppy to be hairless. Coated parents of a hairless dog are obligate heterozygotes and therefore carry one mutant allele. Heterozygotes are carriers and display no hairlessness. At conception, each cub has a 25% chance of being hairless, a 50% chance of being an asymptomatic carrier, and a 25% chance of being coated.
Parker HG, Harris A, Dreger DL, Davis BW, Ostrander EA. 2017 The bald and the beautiful: hairlessness in domestic dog breeds. Phil. Trans. R. Soc. B 372: 20150488. http://dx.doi.org/10.1098/rstb.2015.0488