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Coat Length/Fluffy Locus (LENGTH)

Coat Length/Fluffy Locus (LENGTH)

L Locus (Long Hair/Fluffy), Lh1 (Common Variant Found in Many Breeds), L locus, long hair trait, longhaired trait, short hair trait, shorthaired trait

The length of a dog’s coat can vary between breeds with some breeds typically showing short-haired coats and other breeds showing long-haired coats. It has been determined that hair length variation is due to a mutation in the FGF5 gene that changes the hair follicle growth termination signal which impacts canine hair length. The mutation is recessive which means a dog must have two copies of the mutation that will typically result in a long or fluffy coat. It is important to note that additional breed-specific mutations exist for coat length that are not detected by this test.

Reading Your Results


These dogs have two copies of the normal gene and will neither develop long hair nor pass this mutation to their offspring.


These dogs have one copy of the normal gene and one copy of the mutation associated with this trait. They will not develop long hair and will, if bred, pass the mutation to 50% of its offspring, on average.


These dogs have two copies of the mutation associated with long hair which results in a long-haired coat.

Additional Details


Autosomal Recessive

Affected gene



Ch. 32




Cadieu E, Neff MW, Quignon P, Walsh K, Chase K, Parker HG, VonHoldt BM, Rhue A, Boyko A, Byers A, Wong A, Mosher DS, Elkahloun AG, Spady TC, Andre C, Lark KG, Cargill M, Bustamante CD, Wayne RK, Ostrander EA. Coat variation in the domestic dog is governed by variants in three genes. Science. 2009 Oct; 326(5949):150-3. [PubMed: 19713490]