- Dog Coat Color Genetics -

TERMS

Genotype = the genetic "code" that dictates an animals phenotype.
Phenotype = quite simply, the animal's appearance. This is dictated by the genotype.

PREMADE GENOTYPES

These basic genotypes can be used as "bases" if you are starting out with genetics; markings can be easily added on the end. Unnecessary genes that do not directly affect the dog's appearance or the appearance of its offspring have been omitted. Correct me if I make any mistakes.

Black dog = KK-BB-DD-EE-AyAy
Brindle dog = kbrkbr-BB-DD-EE-AyAy
Liver Brindle dog = kbrkbr-bb-DD-EE-AyAy
Blue Brindle dog = kbrkbr-BB-dd-EE-AyAy
Liver (chocolate) dog = KK-bb-DD-EE-AyAy
Blue dog = KK-BB-dd-EE-AyAy
Isabella dog = KK-bb-dd-EE-AyAy
Red dog = KK-BB-DD-ee-AyAy
Yellow/Gold dog = KK-BB-DD-ee-cchcch-AyAy
Cream dog = KK-BB-DD-ee-cece-AyAy
White dog = KK-BB-DD-ee-cpcp-AyAy
Sable or Fawn dog = kyky-BB-DD-EE-AyAy
Wild Agouti (wolfgrey) dog = kyky-BB-DD-EE-cchcch-awaw (typically)
Grizzled dog = KK-BB-DD-EgEg-AyAy
Progressive Greying dog = KK-BB-DD-EE-AyAy-GG
Black and Tan dog = kyky-BB-DD-EE-atat
Liver and Tan dog = kyky-bb-DD-EE-atat
Blue and Tan dog = kyky-bb-DD-EE-atat
Blue Merle dog = KK-BB-DD-EE-AyAy-Mm
Blue Merle and Tan dog = kyky-BB-DD-EE-atat-Mm
Red Merle dog = KK-bb-DD-EE-AyAy-Mm
Red Merle and Tan dog = kyky-bb-DD-EE-atat-Mm
Blue Roan dog = KK-BB-DD-EE-AyAy-swsw-TrTr (black w/ roaning; Blue Heeler, for example)
Red Roan dog = kyky-BB-DD-EE-AyAy-swsw-TrTr (sable w/ roaning; Red Heeler, for example)
Harlequin dog = KK-BB-DD-EE-AyAy-Mm-Hh
Dalmatian-spotted dog = KK-BB-DD-EE-AyAy-swsw-TdTd
Liver Dalmatian-spotted dog = KK-bb-DD-EE-AyAy-swsw-TdTd

BASE COLORS

K locus = black. Black is dominant, so a dog can be KK or Kky to be black (non-black is kyky, which allows agouti). But keep in mind that the B, D, and E locus overrides K, making a black dog brown, blue, or red. K has one variant, kbr (brindle). Note that to be brindle a dog must have at least one E or Em at the E locus, in order to allow the black to be expressed.
B locus = brown. Brown is recessive, so a dog must be bb to be brown. If a dog is not brown it must be BB or Bb. Note that brown (aka chocolate, liver) dogs always have brown noses.
D locus = blue. Blue is recessive, so a dog must be dd to be blue. If a dog is not blue it must be DD or Dd. Note that blue dogs always have blue noses.
E locus = red. Red is recessive, so a dog must be ee to be red. However, dogs that are genetically "red" may appear to be yellow, cream, or even white due to the intensity of the red, which is managed by the C locus. The E locus also controls two patterns, Em (mask) and Eg (grizzle). If a dog is not red, it can be either EE or Ee, both of which allows black. Note that even though red is a recessive gene, it overrides black, so a KK or Kky dog can still be red if it is ee in the E locus.

-----> C locus = yellow/gold, cream, white. If a dog is red, then the C locus will determine what shade of red it is. The variants are C (full red), cch (yellow/gold), ce (cream), and cp (platinum, aka "white"). Now let's go a bit deeper and describe what shades can result from C combos: Ccch, Cce, and Ccp results in dark gold, cchcch results in gold, cchce and cchcp results in light gold, cece and cecp results in cream, while cpcp results in white. Another possible variant is albino; although complete albino is thought not to occur in dogs, and in general is a little-understood part of canine genetics, a partial albino may be represented by cc (albino). Such a dog would have white fur with clean pink skin (including the nose, lips, eye rims, and paw pads) and, typically, blue eyes. Please note that the C locus is not the scientifically correct term; tests have shown that it is not the C locus that responsible for the intensity of red. However, the C theory still works and as it is the only one we have, we'll stick with it.

PATTERNS

A locus = agouti. Agouti can only appear if the K locus is kyky. Agouti encompasses a large range of dog colors, including Ay (sable or fawn), aw (wild agouti, like wolfgrey), at (tan points), as (saddle), and a (recessive black). The difference between sable and fawn is that a sable (also known as "tipped sable" or "shaded sable") has dark or black hairs intermingled in their coat, while fawn dogs (also known as "clear sable") are one solid color and almost indistinguishable from a recessive red dog. Recessive black is a rare gene exhibited by a few dog breeds, such as the Shetland Sheepdog and German Shepherd. Since a dog needs to be aa for this to work, it explains why pure black in these breeds is rare.
M locus = merle. Merle is dominant, so a dog can me MM or Mm to be merle. However, dogs that are MM are "double merles," which often results in defects such as deafness and blindness. If a dog is not merle it must be mm.
H locus = harlequin. Harlequin is dominant, so a dog can be HH or Hh to be harlequin. However, dogs that are HH never survive to birth. If a dog is not harlequin it must be hh. Also note that to be harlequin a dog must carry the merle gene (Mm).

MARKINGS

T locus = ticking. Ticking is dominant, so a dog can be TT or Tt to be ticked. Please note, however, that ticking is another case of "incomplete dominance," so a Tt dog usually has only light ticking on the legs and muzzle. If a dog is not ticked it must be tt. There are two possible variants, Tr (roan) and Td (dalmatian spots). Each is dominant over t, but please note that for the dalmatian pattern to be properly expressed you need a TdTd. Tdt sometimes results in a roan pattern.
S locus = white spotting. The S locus encompasses si (irish), sp (piebald), sw (extreme piebald) and S (solid). S is said to be dominant over all white patterns. White spotting genes are "incomplete dominant," which means an Ssp dog would be in-between normal piebald and normal solid (it would probably look like an irish-marked dog). As far as we know, SS is solid, Ssi is white trim, sisi is irish (also known as "collared" irish), spsp is piebald, and swsw is extreme piebald. However, remember that these genes can combine. Ssp may result in pseudo-irish, and sisp may result in a "flashy" irish (one with more white than usual). As an added note, remember that piebald is known to be recessive, so a dog may carry piebald but have little white to show for it.

NOTE ABOUT WHITE: Due to natural occurrences which often happen by chance, some dogs may have minute white markings, such as a white mark on the chest or the paws. This is called "residual white" and cannot be genetically predicted, but if you wish to show the presence of this attribute, you can use + to indicate residual white and - to indicated no residual white.