Test of the canine coat length

The coat appearance belongs clearly to the main morphologic distinctions among dogs of different breeds.

There are distinguished three main characteristic hair types of dogs:

• hair length - short/long
• presence/absence of curls
• presence/absence of traits: distinct moustache and eyebrows, characteristic for rough coated dogs

In 2009, Cadieu in cooperation with National Human Genome Research Institute (NIH) and other authors published an article about the results of research of genes participating in dog hair phenotype.
In connection with the hair type, different gene variations in genes RSPO2, FGF5 and KRT71 (encoding R-spondin-2, fibroblast growth factor-5 and keratin-71) have been found that together represent the majority of phenotypes of hair of purebred dogs.

Table (Cadieu et al. , 2009): hair phenotype and genotype

* TT genotype has not been found in this combination; however it probably induces a short-haired phenotype

According to the research, the rough-coated breeds with distinct eyebrows and moustache bear insertion in RSPO2. The appearance of dogs bearing insertion in RSPO2 and also the gene variation c.451C>T in KRT71 is similar to that of rough-coated, but the hair is longer and curlier. Dogs with long hair bear change c.284G>T in homozygous condition in FGF5 gene: If there is an insertion in RSPO2 in addition to this variation, the dogs have distinct moustache and brows and long smooth hair. Dogs with a combination of gene variations in FGF5 and KRT71 have long and curly hair. It is not surprising that the coat must be longer to be curly or wavy, and therefore breeds with such hair are homozygous for c.284G>T in FGF5. If the breed has a combination of all three gene variations, the hair is long, curly with distinct brows and moustache. None of these variations has been found in grey wolfs or in dog breeds with short hair.

Genomia laboratory performs tests of gene variation in FGF5 - a gene determining the length of hair.
It is a change c.284G>T in exon 1 of gene FGF5 with autosomal recessive inheritance.
In dogs with long hair is the change c.284G>T present in both alleles - genotype c.284TT, dogs with short or rough hair have genotype c.284GG or genotype c.284GT - a short-haired carrier of the gene for long hair. Mating two short-haired dogs with genotype c.284GT will result theoretically in 25% of long-haired offsprings (genotype c.284TT).

Genomia performs also RSPO2 test.

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References:

Cadieu E, Neff M, Quignon P, Walsh K, Chase K, Parker HG, Vonholdt BM, Rhue A, Boyko A, Byers A, et al.: Coat variation in the domestic dog is governed by variants in three genes. 2009;326:150-153.

D. J. E. Housley, P. J. Venta: The long and the short of it: evidence that FGF5 is a major determinant of canine ‘hair'-itability, Animal Genetics, August 2006