MyDogDNA Breed Data: Pyrenean Sheepdogs part 1., colours

Pyrenean Sheepdogs (american: Pyrenean Shepherd, french: Berger des Pyrénées) are active, lively herding dogs. The following description in the breed standard describes these dogs very well: “Dog displaying a maximum of nervous energy in a minimum of size and weight. An ever alert physiognomy, a knowing air combined with great liveliness of movement gives this dog a characteristic appearance unlike any other.” In this article we focus on Pyrenean Sheepdog breed data collected with the MyDogDNA –test panel as well as on how to use this data in practice.


The MyDogDNA testing panel includes most of the colours encountered in Pyrenean Sheepdogs.

The genetic basis of the most important colours of Pyrenean Sheepdogs 
- the basic colour is caused by the combined effects of the A-, K-, and A-loci. The possible alleles in each loci are shown horizontally from the most dominant to most recessive allele
- recessive red (ee-red) hides all other colours beneath it
- dominant black (Kb) hides all other colours but ee-red beneath it
- modifying colours (for example merle) modify the dogs colour but leave the basic colour in the background. Multiple modifying colours can affect the dog’s colour at the same time.

E-locus – ee-red doesn’t have to be a problem when breeding​

Three different alleles in the E-locus are seen in Pyrenean Sheepdogs: Em, E and e. The Em-allele is the most dominant allele and causes the dog to have a dark mask around the muzzle. The second most dominant allele “E” causes the mask not to develop. The most recessive allele in this locus is e, that causes the ee-red (cream) colour. Since the e-allele is the most recessive allele in this locus, the e-allele must be inherited from both parents to be expressed. ee-red (cream) is not allowed in the breed standard but it sometimes pops up since the e-allele is recessive. DNA-testing can be used in breeding to know if the dog carries this allele.

Top to down: fawn with mask (masking will develop from genotypes Em/Em, Em/E or Em/e), fawn without a mask (can be caused by genotypes E/E or E/e), ee-red (genotype e/e).​

K-locus – brindle causes trouble in DNA-testing the K-locus​

The K-locus holds three alleles: Kb, kbr and ky. The Kb-allele is the most dominant allele of these three and causes the dominant black colour in Pyrenean Sheepdogs. Dominant black hides all other basic colours beneath it than ee-red. The kbr-allele causing brindle colouration is the second most dominant allele in this locus. The ky-allele is the most recessive allele in this locus. The ky-allele does not cause any change in colouration by itself but lets the colour of the E-locus be expressed. For example fawn Pyrenean Sheepdogs have the genotype ky/ky in their K-locus. The K-locus is difficult to differentiate by DNA-testing since the kbr-allele causing brindle colour has similar molecular structures as the Kb and ky-alleles. DNA-testing can confirm the ky/ky-genotype but dogs with the Kb/Kb or Kb/ky result can also carry the kbr-allele.

Top to down: dominant black (dominant black can be caused by genotypes Kb/Kb, Kb/kbr or Kb/ky), brindle (can be caused by genotypes kbr/kbr or kbr/ky).​


A-locus holds the alleles Ay (sable), aw (wolf grey), at (tan points) and a (recessive black). DNA-tested Pyrenean Sheepdogs have carried only the Ay and at-alleles in the A-locus. Ay is the most dominant and the most common allele in Pyrenean Sheepdogs. This allele causes sable colouration (called fawn in Pyrenean Sheepdogs). The at-allele causes the dog to have tan points. Recessive black and wolf grey are assumed to occur rarely in the breed but none of the tested dogs have yet carried these alleles. It must be noted that the DNA-test for the a-allele causing recessive black has been introduced to the MyDogDNA testing panel in 2016, so there are not yet that many Pyrenean Sheepdogs tested for the a-allele.

The most common allele in the A-locus of Pyrenean Sheepdogs is Ay causing sable (fawn) colouration. Sable colouration can be caused by genotypes Ay/Ay, Ay/at, At/aw or Ay/a.​

B-locus – brown Pyrenean Sheepdogs can be born​

The b-allele causes brown colour occurs rarely in the breed. When homozygous (b/b), it causes the dog’s black colour to turn liver brown. This is not a wanted colour. With DNA-testing, the genotype of the b-locus can be taken into consideration when breeding.