ACD COAT COLOUR BASICS

COAT COLOUR & MISCOLOUR

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COAT COLOUR BASICS

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	ACD genotypes
	ASTCD genotypes
	FAQ

A dog's colour phenotype is what we see.

A dog's colour genotype describes the genes that contribute to his colour.

Every gene has a specific "address" called its locus (pl. loci).
Each gene can occur in more than one form. The variant forms of the gene are called alleles.
The several alleles that may be present at a given locus are referred to a gene series.
The various alleles arise in nature as a result of a mutation of the wild type, or original, gene.
Each locus is occupied by two doses of each gene, one inherited from each parent.
At some loci, the two genes are identical.
At other loci, however, two variants (different alleles) are present.
Genes (and their alleles) are identified by letter names; the letter name may include a superscript, as in a^y.
In a gene series, the wild type allele is commonly (but not always) the allele that suppresses the effect of the other alleles.
The allele that suppresses the others in a gene series is called the dominant allele.
The alleles that are suppressed by others are called recessive alleles.
Where more than two variants exist at a given locus, the alleles can be arranged in order of decreasing dominance.
Genes at some loci interact with the genes at other loci.

Coat colour in dogs involves many loci. In the ACD and ASTCD, three loci are particularly important.

There is more than one allele at each of these three loci.

Some of the alleles produce correct coat colour; others produce miscolours.

Reference
Hewson-Fruend, H J. Inheritance of coat colour in the Australian Cattle Dog and the Australian Stumpy Tail Cattle Dog, in N R Clark: A Dog Called Blue. N R Clark, Sydney, 2003.

AUSTRALIAN CATTLE DOGS

Photos below

Gene series	Known alleles in order of decreasing dominance	Frequency in the ACD breed	Effect		Genotype	Phenotype	Note	Correct colour or miscolour
Gene series	Known alleles in order of decreasing dominance	Frequency in the ACD breed	*Coat colour*	*Nose leather*	Genotype	Phenotype	Note	Correct colour or miscolour
B series	B	Should always be present	Black hairs in a blue ACD. Red hairs in a red ACD	Black	BB or Bb	Blue or red		Correct but Bb carries miscolour
B series	b	Should not be present	Chocolate (brown) hairs	Liver (dark brown, but not black)	bb	Chocolate		Miscolour
A or Agouti series	A	Very rare in ACDs; perhaps lost.	Black hairs in coat but no tan anywhere in the coat		AA or Aa^y or Aa^t	Blue, no tan		Correct
	a^y	Common	Red hairs		a^ya^y or a^ya^t	Red	a^y is incompletely dominant to a^t. An a^ya^t red often has black hairs in his coat.	Correct
	a^t	Common	Black hairs in coat, tan on legs, etc.		a^ta^t	Blue and tan		Correct
E or Extension series	E	Should always be present	Black hairs in a blue ACD. Red hairs in a red ACD		EE or Ee	Blue or red	E allows coat pigment to be fully developed or "extended".	Correct but Ee carries miscolour
E or Extension series	e	Should not be present	Red or black hairs altered to yellow or very pale reddish cream		ee	Yellow or cream	ee stops the development of black coat pigment.	Miscolour


*Correct colour:* Blue and tan	*Correct colour:* Red speckled

Genetically correct colour

The coat colour of both these baby bitches (same litter) is genetically correct but their phenotypes and probable genotypes are both different.

Phenotype: Clear red speckle coat, black nose leather.

Genotype: a^ya^yBBEE

Phenotype: Red speckled coat with very abundant black hairs intermixed with the red; black nose leather.

Genotype: a^ya^tBBEE

a^yis incompletely dominant to a^t and, as a result, this pup has much black hair in her coat (blue overlay). Extreme blue overlay is undesirable.

The pups' dam must be a^ya^tBBEE because her sire was red and her dam blue. The pups' dam, too, has black hairs through her coat, mostly along her spine and in her tail.

The intensity of blue overlay in the coats of a^ya^tBBEE ACDs is extremely variable.

Miscolour

Phenotype: Very pale reddish cream speckled coat; undercoat pale cream; very dark "off-black" nose leather, pale claws (not black as expected).

Genotype: BBee [DNA tested].

Getting on in years, now, but proud to be the first ACD in history to be genetically tested for coat colour. Thanks, Jeremy.

Note: Jeremy's pale colour is not the result of age

Miscolour

Phenotype: Chocolate coat, liver nose leather.

Genotype: bbEE [DNA tested].

This dog works for his living on a cattle station in North Queensland.

Miscolour

Phenotype: Chocolate coat, liver nose leather.

Genotype: bbEE [DNA tested].

Miscolour

Phenotype: Cream with liver nose.

Genotype: Probably BBee [not DNA tested]

A number of other coat colour variations, unacceptable according to the Breed Standard, are known. These include "creeping tan" and "saddle".

	The colour variation known as "creeping tan", where the tan extends to thigh and shoulder (and on the body in some ACDs) is fairly common. In some blue-and-tan ACDs, the blue is restricted almost entirely to the saddle area. The Standard does not allow a fully developed saddle.
Creeping tan

Well defined saddle; incorrect in the ACD.

AUSTRALIAN STUMPY TAIL CATTLE DOGS

Photos below

Gene series	Known alleles in order of decreasing dominance	Frequency in the ASTCD breed	Effect		Genotype	Phenotype	Note	Correct colour or miscolour
Gene series	Known alleles in order of decreasing dominance	Frequency in the ASTCD breed	*Coat colour*	*Nose leather*	Genotype	Phenotype	Note	Correct colour or miscolour
B series	B	Should always be present	Black hairs in a blue ASTCD. Red hairs in a red ASTCD	Black	BB or Bb	Blue or red		Correct but Bb carries miscolour
B series	b	Should not be present	Chocolate (brown) hairs	Liver (dark brown, but not black)	bb	Chocolate		Miscolour
A or Agouti series	A	Common in ASTCDs	Black hairs in coat but no tan anywhere in the coat		AA or Aa^y or Aa^t	Blue, no tan		Correct but Aa^t carries miscolour
	a^y	Common	Red hairs		a^ya^y or a^ya^t	Red	a^y is incompletely dominant to a^t. An a^ya^t red often has black hairs in his coat.	Correct but a^ya^t carries miscolour
	a^t	Should not be present	Black hairs in coat, tan on legs, etc.		a^ta^t	Blue and tan		Miscolour
E or Extension series	E	Should always be present	Black hairs in a blue ASTCD. Red hairs in a red ASTCD		EE or Ee	Blue or red	E allows coat pigment to be fully developed or "extended".	Correct but Ee carries miscolour
E or Extension series	e	Should not be present	Red or black hairs altered to yellow or very pale reddish cream		ee	Yellow or cream	ee stops the development of black coat pigment.	Miscolour


*Correct colour:* Blue (no tan)	*Correct colour:* Red speckled

Miscolour

Phenotype (cream pups): Cream coats; nose leather liver at birth but later changing to "off-black".

Genotype (cream pups): BBee [One pup tested]

Miscolour
(above and right)

Phenotype: Cream coats; nose leather "off-black".

Genotype: BBee

Miscolour
(right and below)

Phenotype: Chocolate coat; liver nose leather.

Genotype: AA (or Aa^t) bb EE (or Ee)

FAQ about ACD and ASTCD Coat Colour

Q1: Is the presence of black hair in the coat of a red ACD a definite indication that the dog is a^ya^t (red, but carries blue)?
A: Abundant black hairs (blue overlay) are a good indication that a red ACD is a^ya^t.

Q2: Could a very pale coat in an ACD or ASTCD (red or blue) be caused by the Dilution gene?
A: No. There is no evidence for the Dilution gene in these breeds. Variation in colour intensity is usually the result of different proportions of red or blue hairs, relative to white hairs (except in the case of some ee miscoloured individuals). The variation is inherited, of course, but we do not yet know how. The term "dilute" should not be used to describe ACDs or ASTCDs with pale coats as it leads to confusion. [The Dilution gene is expressed in some Great Danes; in the presence of dd, black Great Danes become blue but "blue" in this case is truly blue, not a mixture of black and white hairs.]

Q3: Why are some ACDs described as "merle"?
A: The semi-lethal Merle gene, M, is not present in ACDs and ASTCDs and the dogs are not merle-coloured, as we now use the term. Some Australian ACD breeders, in the past, used the term "merle" to describe a blue ACD with no black head markings. Despite our best efforts, a few Australian breeders continue to misuse the term "merle" in this way.

Merle Cardigan Corgi.

Q4: Should we describe ACDs and ASTCDs as roan?
A: Preferably not. There is doubt as to whether the Roan gene, in fact, exists and, even if it does, the Roan gene does not play a part in ACD and ASTCD coat colour. I suggest that a better description of dogs that are not speckled nor mottled (but have white hairs evenly dispersed through their coats) is "evenly ticked" as the Ticking gene does operate in these breeds. The breeders of the 1930s and earlier sometimes used the term "even blue" to describe the colour of their blue dogs.

Q5: Can an ACD have white markings on its feet, like a collie?
A: No. The ACD is a white dog. It is born white and gets its later colour as an expression of the Ticking gene.

New-born blue ACD pups

Q6: Why is a red Australian Shepherd not the same colour as a red ACD?
A: Different genetic makeup. The breeds are not even related. As far as I know, the only thing Australian about the Aussie Shepherd is its name.