Coat colour
How a dog's coat colour is decided
Every dog colour, from jet black to cream, comes from just two pigments: eumelanin, which is black or brown, and phaeomelanin, which ranges from red to yellow. A handful of genes decide which pigment a dog makes, where it goes, and how strong it is. Those genes act in a rough order, which is why two black dogs can have a yellow puppy.
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The genes behind coat colour, in the order they act
Think of it as a set of switches. The E locus goes first: a dog with two copies of its red variant is red or yellow, and the genes further down mostly can't change that. If it can make black pigment, the K locus decides whether the coat is solid; if not, the A locus sets the pattern. Brown and dilute genes then change the shade, and merle and white spotting paint over the top.
| Locus | Gene | What it does | Source |
|---|---|---|---|
| E (extension) | MC1R | Two copies of the e variant limit a dog to red and yellow pigment, from cream to deep red, whatever the other genes say. | Newton et al. 2000 |
| K | CBD103 | One copy of the dominant black variant makes the coat solid black (or brown) and hides the patterns of the A locus. | Candille et al. 2007 |
| A (agouti) | ASIP | Decides the pattern when the K locus allows it: sable, wolf-like agouti, tan points or recessive black, in that order of dominance. | Dreger and Schmutz 2011 |
| B (brown) | TYRP1 | Two brown versions turn black pigment brown (chocolate or liver), including the nose. | Schmutz et al. 2002 |
| D (dilute) | MLPH | Two dilute versions lighten the coat, for example black to grey. Three dilute variants are known. | Van Buren et al. 2020 |
| M (merle) | PMEL (SILV) | An insertion that dilutes colour in patches, giving the marbled merle pattern. | Clark et al. 2006 |
| S (white spotting) | MITF | The major white-spotting gene, behind many white markings and piebald patterns. | Karlsson et al. 2007 |
What a DNA report can show about colour
The PuppyGenes coat colour section predicts possible colour and pattern, colour lightening, white markings and merle where the sample supports interpretation, with its confidence shown. Some results come back tentative or undetermined, and part of a colour estimate can come from the appearance you reported. You can see both kinds of result in our example reports.
All guides
Merle in Dogs: The Gene, Double Merle and Hearing Risks
Merle is the marbled coat pattern of breeds like the Australian Shepherd. Here's the gene behind it, why some merle carriers don't look merle, and what research shows about double merle dogs and hearing.
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Why Do Some Dogs Have Blue Eyes? The Genetics Explained
Blue eyes in dogs come from at least three genetic routes: a gene duplication common in Siberian Huskies, the merle pattern, and white markings that reach the eyes. Here's how each works, and what a DNA test can show.
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Bernedoodle Genetics: Size, Coat, Colours and Temperament
What's inside a Bernedoodle: how big each size gets, why some are tricolour and others solid black, how F1 and F1B coats differ, and what to expect from a Bernese and Poodle mix.
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Cockapoo Genetics: Size, Coat, Colours and Temperament
What's inside a Cockapoo: American and English Cocker parents, how big each size gets, why Cockapoos come in so many colours, how much they shed, and what research says about temperament.
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Labradoodle Genetics: Size, Coat, Shedding and Colours
What's inside a Labradoodle: where the cross came from, why its coats vary more than most doodles', how big it gets, where the colours come from, and what the Australian Labradoodle really is.
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Want to see what your dog's DNA suggests?
A PuppyGenes report covers six sections for your dog: breed ancestry, coat colour, physical appearance, temperament and size predictions, genetic diversity and oral microbiome. The report does not include genetic disease or health screening.
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