What gene causes white markings?
The S locus (white spotting, genetic designation MITF) causes a parti-color or piebald pattern. Another so far unidentified gene causes the Irish pattern typical for Aussies, with white appearing on or around the face, neck, underbody and lower legs. The S gene may contribute to excessive white markings that occur in some Aussies.
Do the white marking genes cause other colors?
No. They block pigment from forming so whatever color the hair might have been, it is white instead.
Are white markings required in Aussies?
No. An Aussie with no white at all is accepted in both the ASCA and AKC breed standards.
How much white can an Aussie have?
Aussies may have a white muzzle, white on the throat and chest, a blaze that may extend into the collar, a collar, white on the underbody, white legs below the elbow and hock, and white on the tip of the tail. White markings elsewhere are considered mismarks though small amounts of white on the ears are allowed.
How are white markings inherited?
The details are still murky, but no or less white is dominant to lots of white. White markings have a continuum from a tiny bit on the chest or toes to a dog that is completely white. Dogs with acceptable markings who have puppies with too much white are carrying genes for the extra white and should be bred to mates from families where excess white does not occur.
If a dog is solid color and has individual white hairs scattered through, is this acceptable?
A scattering of white hair in a black or red coat is uncommon and there is no clear understanding of whether it is inherited. It is arguable whether it is a clear violation of the standard. In any event it is only cosmetic so treat it as a minor fault.
Are there different genes for white markings on different parts of the body (head, collar, leg, etc.)?
Unknown at this time. The exact distribution of white may also be influenced by DNA sequences that regulate gene function. To a small extent the shape of a white marking may be influenced by chance or environment; white markings on cloned animals of other species will vary slightly even though the individuals are essentially identical twins). Particular variations (half-white heads for example) do run in families and some breeds, like the Bernese Mountain Dog, have been selected for very uniform white markings.
Why do some dogs have a scattering of colored spots in their white markings?
This is called ticking. It is caused by the T locus (ticking, specific gene(s) not yet identified). If white markings can be thought of as white spray paint covering the dog’s true color, ticking is like taking a finger and removing small areas of white to reveal the actual color underneath. This is why on some areas of the body the tick marks will be black or red or merle, and on other parts, where tan trim might be, may be copper.
Does T cause other colors?
No, though the ticking can vary from a few spots on an Aussie’s muzzle or legs to the relatively large and uniform spots of a Dalmatian to the densely ticked roan observed Australian Cattle Dogs, some Coonhounds, and other breeds. Occasionally you will see an Aussie with heavy ticking.
How many versions does T have?
Probably two: Ticking and no ticking, with ticking being dominant. We don’t know what governs the variations in size and distribution of the ticking spots.
Is ticking acceptable in Aussies?
The breed standards don’t specifically address it, but a small amount of ticking is generally accepted. Preferences run toward less rather than more.
What determines the color of ticking spots?
Ticking will be whatever color that part of the dog would have been if it didn’t have white markings.
How is ticking inherited?
Dogs with one or two copies of the ticking version of T will be ticked, though the amount will vary. Dogs with two copies of the no ticking version will not be ticked.
Why does ASCA call tan “copper”?
The term probably came into use because the early breeders who formed ASCA were largely ranchers and not familiar with purebred dog color jargon. They likely took their inspiration from dogs with intense color pigment, including tan markings the color of a newly minted penny.
What gene causes tan trim?
The A locus (Agouti, genetic designation ASIP). In the dominant form, the dog shows the base color without tan points or banding on the hairs.
Does A cause other colors or markings?
Yes, sable, wolf grey, and “recessive black” which is actually a lack of tan trim on a black or red dog.
What about merles with tan trim?
Merle isn’t a color, it is a pattern. Blue merles are blacks with the pattern and red merles are reds with the merle pattern acting on the red. Merle does not affect the expression of the tan trim. Other genes determine whether the tan points are a pale cream, sand colored, or rich and coppery.
How many versions does A have?
In order of most to least dominant they are Solid color, sable, wolf sable, tan point, and recessive black. (A, as, aw, at, a)
Are all the A colors and markings acceptable in Aussies?
Both A and a occur in Aussies so Aussies may have tan trim or not. Neither sable nor wolf grey are acceptable and the gene versions that cause them appear to be absent in the breed.
How are the A colors inherited?
– A dog with two sable versions or one sable plus any of the other versions recessive to sable will be sable.
– A dog with two wolf grey versions or one wolf grey plus a tan point or recessive black will be wolf grey.
– A dog with two tan point versions or one tan point and one recessive black will have tan points.
– A dog with two recessive black versions will be black or liver and not have tan trim.
Is there another gene that causes tan trim not to appear on a black or liver dog?
Yes, the K locus (dominant black, genetic designation CBD103). Like the A locus version called “recessive black” (a) this gene can cause a dog without tan points but with a dominant inheritance pattern. While it is called dominant black the gene also acts on red which is the recessive version of black. The dominant K gene can override the at at the A locus to produce a dog without tan points even though he has the gene at the A locus to produce them.
Does K cause any other colors?
No colors, however it does cause brindle pattern. This pattern is most easily observed in dogs that are sable or yellow. In a tan-pointed dog it is only apparent in the areas of tan trim and may not be recognizable as brindle.
How many versions does K have?
Three: dominant black, brindle, tan points possible. (K, Kbr, k)
Are the colors, markings and patterns caused by K acceptable in Aussies?
Aussies may have tan trim or not. Brindle pattern in the tan areas is not considered significant though a full brindle dog (which would also have to have E locus genes for yellow color) would be disqualifying. While not common, the brindle pattern in the tan points does occur in Aussies, particularly in some working lines.
How are the colors and patterns caused by K inherited?
A dog with one or two dominant black versions will not have tan points. The dog’s actual body color will depend on the action of other genes.
A dog with two brindle versions or a brindle and a tan trim possible will be brindle IF it is also yellow or yellow with a black mask. Color of the brindling will depend on what versions of the B locus gene the dog has. If the dog also has the A locus version for recessive black, the dog would have tan trim with brindle in it. Having two copies of the dilution gene will dilute the brindle along with the base coat.
A dog with two tan trim possible versions may have tan trim if the dog has the proper versions of A to have tan trim.