Colour, inheritance & health

Explore a pairing. Understand the possibilities.

Explore a pairing

Parent 1

Harlequin example

Coat example

Genotype (assumed)

K · base colour: KB/KB
D · dilution: D/D
M · classic merle: M/m
H · harlequin: H/n

Edit assumptions

K · base colourD · dilutionM · classic merleH · harlequin

The picture shows the selected coat example. Edited genotypes may describe a different appearance. Brindle requires pedigree interpretation; it is not a direct DNA-test result.

Parent 2

Black example

Coat example

Genotype (assumed)

K · base colour: KB/KB
D · dilution: D/D
M · classic merle: m/m
H · harlequin: n/n

Edit assumptions

K · base colourD · dilutionM · classic merleH · harlequin

The picture shows the selected coat example. Edited genotypes may describe a different appearance. Brindle requires pedigree interpretation; it is not a direct DNA-test result.

Expected outcomes

For the selected genetic scenario

Black base50%
Harlequin25%
Merle25%

Per conception. Actual litters vary.

Coat examples use assumed genotypes. DNA results can change these predictions. Mantle and other white markings are not assigned a percentage.

What this model can and cannot tell you

A scenario, not a breeding clearance

The coat model combines K, D, classic M and H. It assumes a fawn-producing ASIP background, a black mask and black pigment. Other E, A and B variants, exact white spotting, shade, merle repeat lengths and mosaicism are outside this model. Modified fawn/brindle outcomes are labelled by their genes; the illustrations do not predict exact markings.

All coat percentages are at conception. H/H is counted separately; other differences in survival are not modelled. There is no forecast of live litter size or a puppy’s overall health.

For disorders, the calculation covers only the selected recessive variant. It does not calculate the risk of DCM, bloat, hip dysplasia or every possible inherited disease. Those need broader health screening and family history.

Evidence behind the model

Testing-laboratory guidance checked 29 September 2026. The detailed coat references are also retained below.

Harlequin pattern in Great Danes ↗UC Davis VGL
Merle alleles, mosaicism and health ↗UC Davis VGL
Inherited myopathy (IMGD) ↗UC Davis Veterinary Genetics Laboratory
Leukoencephalomyelopathy (LEMP) ↗UC Davis Veterinary Genetics Laboratory
LEMP in Great Danes and Rottweilers ↗University of Minnesota

The seven colours

What each coat looks like and, in one line, what makes it. Open a colour for its genetics.

Seven genes, one coat

A dog carries two copies of each gene, one from each parent, and passes one of the two at random to each puppy. So a dog carrying one copy of a variant passes it to about half its puppies.^[33] A locus is a gene's place on the chromosome. Alleles are the different versions of that gene. Coat colour in Great Danes comes from several loci working together.^[4,30]

Merle comes in sizes

Labs report each merle allele’s size in base pairs (bp). Larger alleles, with longer poly(A) tails, dilute more pigment.

Merle allele size classes
Class	Name	Size (bp)	Typical effect
Mc	Cryptic	200–230	No visible merle
Mc+	Cryptic plus	231–246	No merle pattern; solid coat
Ma	Atypical	247–254	Diluted coat, no patching
Ma+	Atypical plus	255–264	Muted merle pattern
M	Classic	265–268	Classic merle: patches of diluted pigment
Mh	Harlequin merle	269–280	Minimal merle, with areas turned white

These size classes come from Langevin et al. (2018) and are used by labs such as Genomia. That study's 181 dogs were herding and other merle breeds, not Great Danes.^[18,42]
UC Davis reports the measured size (about 200–280 bp) instead of letters, because the naming schemes differ. The categories also overlap: some dogs don't match the pattern their size predicts.^[31,17]
'Mh' is a merle length used across many breeds. It is not the Great Dane harlequin gene (H), which is a separate gene, PSMB7.^[18,31,23]

E locus

The maskGene: MC1R

Em: black mask on the muzzle
E: normal black production, no mask
e: two copies (e/e): no black pigment at all

Dominance order: Em over E over e (the lab also lists a rarer grizzle allele).^[36]
The black mask is inherited as a dominant trait. Every masked dog studied carried at least one copy of the Em variant.^[9]
One study that genotyped fawn and brindle Boxers and Great Danes found every dog was Em/Em.^[10]
Dogs with two copies of e cannot make black pigment (eumelanin).^[37]

How the loci combine

How a harlequin is built

M/mmerleH/nPSMB7KB/–black pigmentHarlequin

Harlequin needs three things together: one merle allele (M), one harlequin allele (H) and black pigment. Remove any one of them and you get a different coat.^[32,20,21]

Double merle and harlequin risks

Two kinds of pairing carry well-documented risks: mating two merle-carrying dogs, and mating two harlequins. Here is what happens and why.

Choose a gene

Merle (M) on a black dog, no harlequin gene.

Parent 1

M locus

Parent 2

M locus

Punnett square · each square is 1 in 4 (25%)

Punnett square: parent 1 egg types down the side, parent 2 sperm types across the top
P1 ↓ · P2 →	M	m
M	M/MDouble merle	M/mMerle
m	M/mMerle	m/mNon-merle

Expected puppies

Double merle
high risk of deafness and eye defects
25%
Merle
50%
Non-merle
25%

Simplified model. It shows one or two genes at a time and holds everything else fixed. Percentages are long-run averages over many litters, and any single litter can differ by chance. Real dogs add complications: merle alleles vary in size and can change between generations, mosaic dogs exist, and brindle can’t be DNA-tested directly. Use lab results, not this calculator, to plan a mating.

M/M

Double merle

A double merle has two copies of merle (M/M). It comes from mating two dogs that both carry merle. In Great Danes that includes harlequins, because every harlequin is also a merle.^[20,32]
When two single merles (M/m) are mated, each puppy has a 25% chance of being a double merle.^[40]
Double merles are mostly white and are prone to several health problems.^[40,31]
They are sometimes called 'lethal whites', which misleads: harlequin breeding records counted 35 white (homozygous merle) pups. Combined with H, though, double merles seem to survive less often.^[20,21]

Hearing

In a BAER hearing study of 153 merle dogs, 10% of double merles were deaf in one ear and 15% in both. For single merles the figures were 2.7% and 0.9%.^[24]
Pigment-linked deafness happens when the blood supply inside the cochlea breaks down at about 3–4 weeks of age. It is thought to follow the loss of pigment cells caused by merle or piebald genes.^[26]
Only a BAER test can confirm deafness, especially deafness in one ear, which is easy to miss at home.^[25,26]

Eyes and more

Merle dogs, whether one or two copies, can show hearing and eye problems like those of Waardenburg syndrome in people.^[14]
In a study of Dachshunds, 11 double merles had severe eye defects in varying forms: small eyes (microphthalmia), small corneas, small or off-centre pupils, cataracts and colobomas (gaps in eye structures). Single merles showed milder changes, such as a missing tapetum (the eye's reflective layer) and a depigmented retina, which some double merles also had.^[27]
Double merles may also have skeletal and other defects.^[31]
A dog carrying a hidden, mosaic merle allele produced a double merle puppy born without eyes (anophthalmia).^[19]

If you have one

If you own a mostly white Dane from harlequin or merle breeding, ask your vet about a BAER hearing test.^[25]
Deaf dogs should not be bred.^[26]
To avoid producing double merles, breed a merle dog only to a dog that carries no merle at all, cryptic merle included.^[40]

A deaf or visually impaired Dane is still a Dane. Talk to your vet about training and safety for a dog who can’t hear or see well.

H/n × H/n

Harlequin × harlequin

Mating two harlequins (H/n × H/n) means about 25% of embryos are H/H and die before birth.^[32,39]
Harlequin × harlequin matings are not linked to stillbirths. The H/H loss probably happens early in pregnancy, which is why these litters tend to be small.^[6]
Harlequins don't breed true: they almost always produce merle puppies, and in harlequin × harlequin matings about a quarter of the offspring are expected to be double merles.^[6]
In Sponenberg's harlequin × harlequin records, 214 pups were 60 black, 77 harlequin, 42 merle and 35 white. The whites were homozygous merle.^[20]
The white puppies from harlequin breeding are double merles (M/M), not a separate 'white' gene, so every double-merle risk above applies to them.^[20,21]
Black and mantle dogs from harlequin lines can carry H without showing it.^[39,32]

Try it in the calculator above: choose “Harlequin × harlequin” to see the expected split next to the recorded litters.

Colour families and DNA tests

Great Dane breeders traditionally keep colours within families. Here is what those families are, why they exist, and which DNA tests now do the job better.

Fawn & brindle
Fawn · Brindle
- Fawns and brindles are bred to each other.^[4]
- The FCI treats fawn and brindle as one colour variety.^[2]
- In breeding among brindles, fawns and blacks, at least one parent should be free of blue. Two blue carriers (D/d) can produce blue fawn or blue brindle puppies, which are not recognised colours.^[6,1]
Black & blue
Black · Blue
- Blues are generally bred to blues, which gives all-blue litters.^[4]
- Geneticist Neil O'Sullivan describes the GDCA's new colour code for black and blue: don't mate two carriers of fawn or brindle, and make at least one parent KB/KB (two copies of dominant black).^[6]
- The FCI keeps blue as its own variety.^[2]
Harlequin, mantle & merle
Harlequin · Mantle · Merle · Black
- Harlequins, mantles, merles and black-and-whites make up one breeding group.^[4]
- The FCI's second variety covers harlequin, merle and black, and its black includes the mantle and the 'Plattenhund'.^[2]
- Breeding merles or harlequins to mantles gives a high proportion of show-marked harlequins.^[6]

Why families exist

Before DNA tests, breeding within colour families was the only way to control or predict the recessive colours a dog carried.^[6]
The GDCA's original colour code relied on dogs being clear of certain colours for four generations. It still allowed harlequin × harlequin matings.^[6]
Merle only lightens black pigment, so on a mostly yellow coat such as fawn it can go unseen. Bringing fawn or brindle into harlequin lines therefore risks hidden merle and accidental double merles.^[31,19]
Harlequin only shows on a merle dog that makes black pigment, and H can pass unseen through non-merle dogs. Keeping colours within their families was how breeders avoided the undesirable combinations that mixing produces.^[32,39,6]
Now that merle is accepted and DNA tests exist, the GDCA says it is preparing an updated colour code.^[5,6]

DNA tests and when to use them

Test	What it tells you	When to use it
MerleM · PMEL	Whether the dog carries merle, and the size of each allele (reported as about 200–280 bp or as Mc–Mh classes).^[31,18]	Before breeding any dog from harlequin, merle or mantle lines, fawns and brindles included. Cryptic, hidden and mosaic merles can't be recognised by eye.^[19]
HarlequinH · PSMB7	N/N or N/H. H/H is not seen in living dogs.^[32]	For blacks and mantles from harlequin lines, which often carry H unseen, and to avoid H/n × H/n embryonic loss.^[39,32]
DiluteD · MLPH	D/D, D/d carrier, or d/d blue.^[33]	Before mating blue lines with fawn, brindle or black, to avoid pairing two carriers.^[6]
Dominant blackK · CBD103	Whether the dog has zero, one or two dominant black copies. Brindle can't be tested directly.^[34]	To find KB/KB blacks and blues, which can't produce fawn or brindle puppies.^[6,8]
White spottingS · MITF	0, 1 or 2 copies of the tested piebald variant, which works by dose in Great Danes.^[38]	In mantle and harlequin breeding, to help predict how much white the puppies will have.^[38,41]
Mask and AgoutiE · MC1R, A · ASIP	Mask (Em) and A-locus type. The A locus is on the Great Dane panel.^[36,30]	Mostly of interest in fawn and brindle lines. In dogs with dominant black, A-locus patterns are hidden.^[35]

Merle M · PMEL

Whether the dog carries merle, and the size of each allele (reported as about 200–280 bp or as Mc–Mh classes).^[31,18]

When Before breeding any dog from harlequin, merle or mantle lines, fawns and brindles included. Cryptic, hidden and mosaic merles can't be recognised by eye.^[19]

Harlequin H · PSMB7

N/N or N/H. H/H is not seen in living dogs.^[32]

When For blacks and mantles from harlequin lines, which often carry H unseen, and to avoid H/n × H/n embryonic loss.^[39,32]

Dilute D · MLPH

D/D, D/d carrier, or d/d blue.^[33]

When Before mating blue lines with fawn, brindle or black, to avoid pairing two carriers.^[6]

Dominant black K · CBD103

Whether the dog has zero, one or two dominant black copies. Brindle can't be tested directly.^[34]

When To find KB/KB blacks and blues, which can't produce fawn or brindle puppies.^[6,8]

White spotting S · MITF

0, 1 or 2 copies of the tested piebald variant, which works by dose in Great Danes.^[38]

When In mantle and harlequin breeding, to help predict how much white the puppies will have.^[38,41]

Mask and Agouti E · MC1R, A · ASIP

Mask (Em) and A-locus type. The A locus is on the Great Dane panel.^[36,30]

When Mostly of interest in fawn and brindle lines. In dogs with dominant black, A-locus patterns are hidden.^[35]

UC Davis offers a Great Dane colour panel (A, D, K, H and S). Merle is a separate test. Hearing is checked with a BAER test, not DNA.^[30,31,25]

Coat colour and health: what's real, and what's myth

Only a few health problems are genuinely linked to coat colour. For the breed’s major health risks, such as bloat and heart disease, see Health.

Real, evidence-backed

Double merle: hearing and eyes

Double merles are much more likely than single merles to be deaf, and they can have serious eye defects.^[24,27,14]
Single merles have a small but real risk: 2.7% were deaf in one ear and 0.9% in both.^[24]
Merle dogs with the largest size class (Mh) seem more prone to hearing or vision problems.^[18]

Harlequin: H/H embryonic loss

H/H embryos die before birth, probably early in pregnancy, so harlequin × harlequin litters tend to be smaller.^[23,6]
H also seems to lower the survival of double-merle puppies.^[21,20]

Blue: colour dilution alopecia?

Colour dilution alopecia (CDA) is an inherited coat disorder of dilute dogs: a dry, brittle coat with patchy, progressive hair loss, usually starting between 6 months and 3 years of age.^[29]
The evidence for Great Danes is mixed. WikiVet lists the breed among those affected, but Laboklin writes that the Great Dane's blue does not appear to be affected.^[29,28]
Not every dilute dog develops CDA, and no DNA test can tell which dilute dogs will.^[28]

Myths to avoid

MythWhite Danes are albinos.: Whites from harlequin or merle breeding are double merles (M/M): merle's lightening effect doubled, which is why they carry its hearing and eye risks.^[20,40]
MythEvery double merle is deaf and blind.: The risk is much higher but not certain. In one study 25% of double merles were deaf (10% in one ear, 15% in both), and eye defects varied in severity. The risk is avoidable: don't mate two merle carriers.^[24,27,40]
MythA fawn or brindle can't carry merle.: Merle only lightens black pigment, so it can hide on a yellow coat. Test before breeding.^[31,19]
MythHarlequin × harlequin is fine because H/H puppies are never born.: H/H embryos die before birth, which shrinks the litter, and about a quarter of the puppies are still double merles.^[32,6]
MythA cryptic merle is the same as no merle.: Merle lengths can grow between generations, and some dogs are mosaics. A dog with no visible merle but a harlequin-size allele produced a double merle.^[19,16,17]
MythEvery blue Dane will lose its coat.: CDA is linked to dilution, but the evidence in Great Danes is mixed and many dilute dogs never develop it.^[28,29]

Colour, inheritance & health

Explore a pairing

Expected outcomes

A scenario, not a breeding clearance

Evidence behind the model

The seven colours

Seven genes, one coat

Merle comes in sizes

E locus

K locus

A locus

D locus

S locus

M locus

H locus

How the loci combine

Double merle and harlequin risks

Double merle

Hearing

Eyes and more

If you have one

Harlequin × harlequin

Colour families and DNA tests

Fawn & brindle

Black & blue

Harlequin, mantle & merle

Why families exist

DNA tests and when to use them

Coat colour and health: what's real, and what's myth

Real, evidence-backed

Double merle: hearing and eyes

Harlequin: H/H embryonic loss

Blue: colour dilution alopecia?

Myths to avoid