One of the most obvious gross morphological differences among dogs of different breeds is the length of their hair. For the majority of registered dog breeds, the breed standard allows only one hair length. However, variable hair lengths are allowed by the standard for some breeds. Long-haired coat length is inherited a an autosomal recessiv trait, therefore dogs that are carriers of the long hair mutation will appear to be normal (short hair) themselves but will likely pass on the long-hair mutation 50% of the time.
This mutation Coat Length II is only valid for Afghan Hound, Akita Inu, Alaskan Malamute, ChowChow, Eurasian, Husky, Prager Rattler and Samoyed, however it is important to point out that these breeds should also be tested for Coat Length I which is valid for all dog breeds. One test will not give you the full status.
The DNA test allows to distinguish between 3 possible genotypes:
1. L/L Short Hair having 2 copies of the normal short-hair allele 'L'.
2. L/l Short Hair carrying the long hair mutation - carrier having 1 copy of the normal short-hair allele 'L' and 1 copy of the long-hair mutation 'l'.
3. l/l Long Hair having 2 copies of the long-hair mutation 'l'.
Short Hair (L) is dominant over Long Hair (l)