This test is for the 'bd', 'bc' and 'bs'variants, which are described in all dog breeds and are responsible for the brown coat colour, which is also known in some breeds as liver, chocolate, chestnut, sedge, and less frequently, red. Two copies of the b-allele are needed to dilute black pigment to brown. For red or yellow dogs, the brown allele does not dilute the hair colour, but will change the colour of nose and foot pads from black to brown if two brown alleles are present.

When one of the variants is found homozygous (bd/bd, bc/bc or bs/bs), dark pigment (eumelanin) is diluted to brown in the pigmented areas. However, when several variants of the B-locus are found in heterozygous state (example N/bd and N/bc), it is not always possible to directly determine the influence on the eumelanin because this depends on whether the variants are located on the same or different chromosmes, however, the dog will definitely pass the variants to its offspring.

Australian Shepherd and Lancashire Heeler

French Bulldog

The D locus is the primary locus associated with diluted pigment, which results in coats that would otherwise be black or brown instead showing up as gray, or blue in the case of black, and pale brown or Isabella / Lilac / Lavender in the case of brown. The melanophilin gene has recently been shown to be responsible, but not all of the dilute causing mutations have been identified yet.

A recessive mutation in the melanophilin gene was identified as the cause of colour dilution phenotypes in the dog. Two alleles (variants) are described: the dominant full colour (D) and the recessive dilute (d). Two copies of dilute are needed to lighten black pigment to blue / grey and brown (liver / chocolate / cocoa / red in border collie) pigment to lilac / isabella / lavender (in Pomeranian). A diagnostic DNA test identifies the specific variants of the MLPH gene.

Please note that in the Chow Chow, Thai Ridgeback and Sloughi breeds, there is another mutation that can cause coat colour dilution, it is the D2 Locus mutation and in those breeds both D1 Locus and D2 Locus mutations must be tested for complete analysis.

Please note that in the Chihuahua, Italian Greyhound, Mudi (Hungarian Mudi) and Hungarian Pumi breeds, there is another mutation that can cause coat colour dilution, it is the D3 Locus mutation and in those breeds both D 1Locus and D3 Locus mutations must be tested for complete analysis.

Please note that dilution (blue, lilac, isabella, etc) is just a colour and that it is not known to be associated with any health conditions

KC

Please note that this test is part of the KC DNA testing scheme in Labrador Retriever. If you would like Laboklin to send the result to the KC, please sign the declaration at the bottom of the form to give us a permission . Please note that the KC will oly publish clear results but would make a note of any result received.

Colour Dilution Alopecia (CDA)

CDA is a genetic recessive inherited condition that causes patches of hair thinning or loss and may also include flaky and/or itchy skin. CDA occurs in dilute dogs (homozygous for the dilute gene d/d) in some breeds, however there is no direct link between CDA and the dilute gene, and there is no evidence that the dilute gene is responsible for CDA. It is though that there are other, not yet identified, genetic factors causing CDA in dilute dogs of some breeds. Any colour can carry CDA but symptoms are only expressed in blue and isabella dogs affected by CDA.

breeding

Since CDA is a recessive gene, it can, in theory, be bred out of most lines by breeding dilute dogs with healthy coats. Breeding healthy dilute dogs with healthy dilute dogs is one way to reduce the occurrence of CDA until testing becomes available.

Breeds known to be affected by CDA:

• Bernese Mountain Dog
• Boston Terrier
• Chihuahua
• Chow Chow
• Dachshund
• Doberman Pinscher
• Great Dane
• Irish Setter
• Italian Greyhound
• Mudi (Hungarian Mudi)
• Newfoundland
• Saluki
• Schipperke
• Shetland Sheepdog
• Standard Poodle
• Whippet
• Yorkshire Terrier

Coat Colours

As with other mammals, dogs have two major types of pigment in their coat: dark pigment (Eumelanin) which is responsible for black and brown in the pigmented areas, and yellow pigment (Phaeomelanin) which is responsible for red, yellow, orange, golden, cream, apricot in the pigmented areas. The colour varieties seen in dogs are due to genes controlling the amount, extent, and distribution of these two colour pigments.

E-Locus

The 'e1' variant

Australian Cattle Dog

E-Locus Special colours: 'eA', 'eG' and 'eH'

EM-Locus Melanistic Mask

Order of dominance: EM> EG> E> EH> e.

The K locus plays a pivotal role in coat colour. This locus is a relative newcomer in our understanding of canine colour, and includes traits formerly attributed by some to other genes.

The dominant allele in the series is K^B, which is responsible for self-colouring, or solid coloured fur in pigmented areas. This trait was formerly attributed to the Agouti (A) locus as A^S, but recent breeding studies had shown this not to be the case.

There are two other alleles, k^br, and k^y. K^B is dominant to both k^br and k^y, while k^br is dominant only to k^y. k^br is responsible for the brindle. The recessive allele, k^y, allows the basic patterns of the A locus to be expressed. So too does the k^br allele, but with brindling of any tan, fawn, or tawny areas. Any animal with at least one K^B allele will be self-coloured.

Any animal with at least one k^br allele, and no K^B alleles will be brindled on agouti background (see A locus). Any animal with two k^y alleles will show agouti patterns (see A locus). and k^y

LABOKLIN can presently test for these two alleles. In some breeds, where no brindle is present, this represents a complete analysis of the locus. An example would be the Pug. In breeds where the breed standard disqualifies all but self-colored dogs, testing for these two alleles is once again all that is needed. Any animal with two K^B alleles cannot produce anything except self-coloured offspring. A prime example here is the Labrador retriever. In breeds where many variations are allowed, these tests can help predict the probability of potential litters to include fawn, sable, tawny, tan point, tricolor or recessive black puppies.

NEWS: BRINDLE IS NOW SOLVED….

I-Locus controls the intensity of the red pigment (phaeomelanin). Phaeomelanin is the tan pigment including all shades of red, gold, fawn, sable and cream pigments. The richness of the red colour varies in the different breeds and within a breed, from the very rich red of the Irish setter to cream. This intensity is controlled by the I-Locus which has recently been identified.The dominant I-allele stands for intense phaeomelanin (red, orange, yellow), the recessive i-allele is responsible for for cream, cream-white or white.

The expression of the phaeomelanin on the dog body, is initially determined by the loci E, K and A locus. The I-Locus decides how bright or rich the red colour is.

A test is now available at Laboklin.