School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
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Coat Colour in the Australian Cattle Dog

 

On this page I discuss coat color. First, I cite the relevant section from the standard. Next, I present a brief section on the genetics of coat colour. It is not intended to be a complete description of all genes/modifiers/promoters. Rather it is a practical introduction and perhaps a reminder to breeders. Some excellent pictures of dogs with different coat colours can be found on the Kombinalong web site.

 

Australian National Kennel Council 1994 F.C.I. Standard No. 287
Blue - The colour should be blue, blue-mottled or blue speckled with or without other markings. The permissible markings are black, blue or tan markings on the head, evenly distributed for preference. The forelegs tan midway up the legs and extending up the front to breast and throat, with tan on jaws; the hindquarters tan on inside of hindlegs, and inside of thighs, showing down the front of the stifles and broadening out to the outside of the hindlegs from hock to toes. Tan undercoat is permissible on the body providing it does not show through the blue outer coat. Black markings on the body are not desirable.

Red Speckle - The colour should be of good even red speckle all over, including the undercoat, (neither white nor cream), with or without darker red markings on the head. Even head markings are desirable. Red markings on the body are permissible but not desirable.

Brief genetics of coat colour the Australian Cattle Dog
The most significant genes in most Australian Cattle dogs are are agouti (A), spotting (S) and ticking (T). Briefly, puppies are born white and the coat converts to blue or red under the modifying gene ticking. The patches are either black or red depending on which agouti (A) allele the dog carries. The spotting gene (S) determines where spots occur on the body.

The cause of creeping tan (where tan extends on to the thigh and shoulder) remains elusive. Casual observation, suggests that creeping tan only occurs on plane face dogs.

Understanding the genetic basis of coat colour is expected to contribute to the debates concerning the replacement of "even read speckle" with "red, red-mottled or red speckled" AND the replacement of "Red markings on the body are permissible but not desirable" with "Red markings on the body are not desirable."

 

A- Agouti series
The agouti gene is on chromosome 24. This gene undoubtedly has several alleles, but how many is still an open question. Some have been identified using DNA studies and tests for agouti phenotypes in some breeds will become available soon.

 

A Self coloured blue (probably very rare)
ay Red (this gene is dominant to at)
at Bicolour (blue with tan points)
ag Agouti (wolf grey)
as Saddle marking (black saddle with tan on the rest of the body)

 

Most blue dogs are at at (blue with tan points as shown by the picture on this page) very few are AA. Most red dogs are ay ay.
As ay is dominant over at blue parents are expected to produce blue pups. Homozygous red dogs are expected to produce red puppies. Heterozygous reds ay at may produce red and blue pups. In other words, if you mate 2 red dogs and get a blue pup then both parents must be heterozygous for A. However, it is clear that there is incomplete dominance between ay and at. For example, ay at red dogs may have some dark hairs in the red.

To complicate things, agouti has more than one promoter which seems to signal where on the body, or even on individual hairs, each pigment is laid down. Roughly one seems to control ventral or belly colour and the other dorsal or back colour. The simplest way to "see" this is on a black and tan dog......the back is black from eumelanin pigment being made and the belly is tan or red from phaeomelanin pigment being made. In some dogs banded hairs are produced over parts of the body. With certain genotypes, the coat color changes from birth to adulthood, usually being born darker and then lightening. It is possible that different promoters/ alleles of agouti is the cause of "creeping tan" but this is not known.

Berryere T.G, J. A. Kerns, G. S. Barsh, S. M. Schmutz. 2005. Association of an Agouti allele with fawn or sable coat color in domestic dogs. Mammalian Genome16:262-272.

S-Spotting Series
This gene has at least four alleles or variants.

S Normal colour
si Irish spotting
sp Piebald spotting (white with large coloured patches on the head and body)
sw

Extreme white piebald spotting (white with large coloured patches possibly limited to the head).

Some dogs who are born white are also deaf. These white dogs are usually those that are white from merle crosses or from the "Irish Spotting Pattern".

T – Ticking series
Ticking is observed only in conjunction with the recessive alleles of the spotting gene S. The ranges of variation from a light speckle to a marked mottle suggest that there are several modifiers operating.

T Ticked; with pigmented spots in a light coat
t normal pigment.


Other genes of interest
B-Black Series
The recessive, b, has been documented and causes red/liver on the nose eyelieds.

E- Extension series
The recessive allele hides the effect of black and results in a pale red or cream dog.

 

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