|It has often been said that the ACD only come in two colors --- ticked-black/tan or red. With the help of DNA testing,
this has now proven to be untrue.
An ACD may also be brown, called "chocolate", red (non-extension, e/e, red, instead of sable red) or white. Brown,
red and white are not common colors. The reason these colors are not seen very often is because they are not
actively being bred for, when produced - are not advertised for fear of reprisal from other breeders and some
puppies are actually put to sleep if they are any color other than that of the breed standard.
The brown ACD, called "chocolate", is produced when two dogs that are heterozygous at the B Locus (B/b) are
mated and the offspring receive two copies of the recessive allelic pair -- b/b.
It is believed that the Brown Locus codes for an enzyme, tyrosinase-related protein 1 (TYRP1), which catalyzes the
final step in eumelanin production, changing the final intermediate brown pigment (dihydroxyindole) to black pigment.
SO, ALL dogs start as BROWN and after the final step --- this directs the color to be black.
When brown (b/b) is expressed, it means that the final step in eumelanin production has not been completed and the
pigment remains brown. The brown color is not a genetic defect.
When the alleles are in the homozygous or heterozygous dominant form of B/B or B/b, the color and pigment (nose,
eye rims and lips) remains (or directs the color to be) black.
When the alleles are in the homozygous recessive form (b/b), the color and pigment will be brown. This just means
that the final step in eumelanin production of changing brown to black did not occur. Phaemelanin (yellow/red [e/e])
is not affected. BUT, in the e/e colored dog, if the dog is also b/b; they will be either red or yellow and will have
brown pigment (nose, eye rims and lips). The pigment granules produced by "bb" are smaller, rounder in shape,
and appear lighter than pigment granules in "B" dogs. The iris of the eye is also lightened.
Brown dogs can either be "ticked-black/tan" or "red" ACD's.
The "ticked-black/tan" dog -- when b/b, will appear brown with tan points and will have a brown nose, eye rims and
lips. The color looks like the color of a German Shorthair Pointer with tan points. The tan points are visable,
because the alleles at the B Locus only affect eumelanin and not phaeomelanin.
The sable "red" dog -- when b/b, will appear like a brown sable and have a brown nose, eye rims and lips.
An "e/e" red dog that is b/b, will be red (not brown) and will have a brown nose, eye rims and lips.
|Copper is a chocolate/tan ACD owned by
Matthew Whitaker. His genotype is b^b a^t/a^t
--- had it have been B^b or B^B ---
he would have been a standard colored ticked
black with tan points (called "blue").
For more information on Matthew's chocolate
ACD's and/or his litter of puppies, please
contact him. Click on EMAIL for his email
address. Matthew says that Copper is an
awesome dog at working cattle.
|This is a litter of pups that was sired by
Copper. The dam of the litter is a standard
ticked black and tan - called "blue" by ACD
owners and breeders. She is a carrier of the
"b" gene. ACD's are born white, you can
obviously see that the pup in the front is going
to be a chocolate color. His sister is also a
chocolate color, she is laying to the back of
him. The other pups are standard ticked black
(called "blue" in the ACD world)
and would all be carriers of the "b" gene,
making their genotype "B^b".
|This pup is a chocolate sable (a^y) ACD. Her
genotype is b^b a^y/a^t (she carries tan point); if it
had of been B^b or B^B, her color would have
been a standard "red" (genetically a ticked sable).