Dogs are either black or brown ---- other alleles (genes) act upon each other to create different colors or
different shades of colors. It is theorized that all breeds of dogs have all of the alleles for different colors.
Some dogs have been selectively bred over many years to be dominant for a certain color or colors. A few
examples would be the Kelpie, Australian Cattle Dog, Golden Retriever, Irish Setter, Weimaraner, Lab etc...

When you are looking at coat color, it is best to look at the entire picture. The entire picture being all the
alleles that encode for color. We will look at each individual allele and then put them together for the
complete coat color.

Keeping in mind that each puppy receives a copy of each allele from their parents.

The first listed allele is expressed, the second one is hidden or carried. If one parent is brown (b/b) [also
called chocolate] the "b" allele is the ONLY one that can be copied and inherited by the puppy. So, the puppy
will receive a copy of the "b" allele from one parent. If the other parent is B/B the only allele that the puppy
can receive is "B". So, every puppy will be B/b -- black, carrying brown.

If one parent is B/b, the puppy can receive either "B" or "b". If the other parent is also B/b, the puppy can
receive either "B" or "b". The puppies could be: B/B - black; B/b - black, and carrying brown; or b/b -

The 'address' where the genes are located are called Locus (Loci is the plural). Each Locus contains the
different genes that are responsible for encoding (telling) coat color. Some also change skin pigment (like
the nose, eye rims and lips).

Each Locus, with it's genes, are important, because a breeder can either breed a certain color into their
breeding program or breed it out. A breeder can either lighten or darken the coat color, also. Coat color can
also prove sometimes that the sire, the person says sired the litter, couldn't genetically be the right one.

Pigment distribution patterns are controlled by the E and A Loci.

The E Locus is important because the genes from this Locus are responsible and control black (E/E or E/e)
and red (e/e) color.

If a dog is the
black (E/E or E/e) color, ---- as other color genes are added, the color either changes or
remains black. Think of it like baking a cake. The batter would be the main ingredient and all other
ingredients either change the color of the batter, or leave it the same.

If a dog is the
red (e/e) color, ---- as other ingredients are added, the color remains the same (red or yellow).
This is what is called "homozygous recessive dominant". The red color is the red color you see on an Irish
Setter. It comes in different shades. The Golden Retriever, Yellow Labrador, Cream Working Kelpie, white
Anatolian are all red (e/e). The color of some Coolies that are currently being called "red", is really the brown
color (b/b). I'll discuss this color later.

The A Locus:

contains the genes that encode for sable (a^y), wolf (a^w), saddle (a^s), tan points (a^t), and recessive black
(a^a). In order for this coloration to be expressed (seen), the dog must also be "k/k". All Coolies that have tan
points are "k/k", all Coolies that do not have tan points are either "K/K" or "K/k". If you breed two dogs that
have tan points, EVERY puppy in the litter will have tan points. If you can't see any tan points, look
underneath the tail --- it's usually there before any place else on the body.

Color that is modified by diluting colors are controlled by the B, C, D, and M Loci.
The dog will inherit all of these genes, either in the dominant or recessive form.

These genes are the "ingredients" that will either: not change, lighten, or darken the color of the coat.

Let's start with dogs that are
black (K/K or K/k), [remembering that one copy of the gene comes from the dog
and one copy comes from the bitch]. Since the alleles are in the dominant form, the alleles at the A Locus
can not be expressed (tan points can not be expressed, but may be 'carried' [hidden]). These are the solid
colored and self-merle dogs (no tan).

If the puppy gets the "B" gene (black) from his sire and a "B" gene from his dam; he is then B/B. This says to
stay black and not carry brown. If the Merle gene is added, the color would be black merle (called blue merle
in the Coolie breed).

If the puppy gets B/b --- this says to stay black, but carry brown (this is a hidden color and you can't see it). If
the Merle gene is added, the color would be black merle.

If the puppy gets
b/b (brown) --- this says to turn the color to brown (chocolate). This coloration also turns the
nose, eye rims and lips brown. It also will lighten the iris's of the eyes. When bred to another dog with this
gene combination, ONLY brown puppies will be produced. If the Merle gene is added, the color would be
chocolate merle (called red merle in the Coolie) and will have a brown nose, eye rims and lips.

The next gene added are the
"D" genes. If he is black (B/B or B/b) and gets D/D, his black color remains the
same. If the Merle gene is added, the color is still black merle.

If he is
black (B/B or B/b) and gets D/d, his black color remains the same, but now he is carrying "d". If the
Merle gene is added, the color is still black merle.

If he is black (B/B or B/b) and gets d/d (which is the homozygous recessive form), that will dilute the black
color to
blue. The nose, eye rims and lips will be gray. Sometimes, they are dark gray. The iris's are also
lightened. If the Merle gene is added, the color will dilute to blue merle. This merle is true blue (d/d) merle
and is much lighter than the black merle. In the true blue merle, all of the black patches have been diluted to
blue, gray, and pewter colors (no black color is found). The nose, lips and eye rims will be also be gray.

If he is brown/chocolate (b/b) and gets D/D or D/d, his color remains
brown/chocolate. The nose, lips and
eye rims are brown. If two dogs are mated that are both b/b D/D, all of the puppies will be brown. If the Merle
gene is added, the color would be chocolate merle.

If he is brown/chocolate (b/b) and gets d/d, then his brown is diluted to a dull, flat silvery-brown color called

dilute brown
(called Lilac in the Border Collie breed). The nose, lips and eye rims are a rosey-gray color. If
two dogs are mated that are both b/b d/d (Lilac), all of the puppies will be Lilac. If the Merle gene is added,
the color will be a Lilac Merle. This color is a very light coloration. Some puppies are born very light in color
and darken with age.

The next genes added are the
C genes. If the puppy gets C/C to any combination of the B and D genes, his
color is dictated by the B and D genes. **NOTE: most dogs are C/C.

If the puppy gets the
Chinchilla gene, this gene will not have any noticeable affect on the black colored
puppy. If the puppy is a black merle, the diluted patches or gray, lighten to light silver.

If the puppy is blue, this gene will lighten him to a silverish blue color. If the puppy is a blue merle, the diluted
patches will lighten even more.

If the puppy is brown/chocolate, this gene will lighten him to a light colored milk chocolate. If the puppy is a
chocolate merle, this gene will lighten the patches even more.

Dogs that are k/k: remember that when the "K" is in the recessive form (k/k), it allows the expression of the
alleles at the A Locus.

The coloration, according to the gene pairs the dog has, would be the same as above, except now ----
whatever the dog is carrying at the A Locus is also expressed. For example: now the tan points are

Let's now talk about dogs that are
red/yellow (e/e). This is a mutation and does not allow any black hair
to be produced. It doesn't matter what other genes are present, the dog will be red, yellow, or tan.
The color shades can vary anywhere from white, pale yellow, biscuit color, butter cream, to a burnt red, fox
red, orange, to a copper penny color. The color depends greatly on the genes at the D and C Locus. This
coloration is found in the Coolie breed.

Dogs that are (e/e) can range in the colors listed above and if they have a black nose, lips, eye rims, are
said to be genetically black.  

Dogs that are (e/e) and brown (b/b), the color will not change to chocolate. However, the nose, lips, eye rims
will be brown - readily identifying the dog as being genetically brown.

Dogs that are (e/e) and blue (d/d), the color will be diluted to yellow (this is the fact *most* of the time, but not
always -- the dog could be a reddish color).  The nose, lips, eye rims will always be gray - readily identifying
the dog as being genetically a diluted black (blue).

Dogs that are (e/e) and brown (b/b) and blue (d/d), since the brown has no color changing effects, but blue
does ---- the dog will be diluted to yellow.  The nose, lips, eye rims will be a rosey-brown.

NOTE: if the dog is K/K or K/k --- the tan points can only be carried, not expressed. If the dog is k/k, the tan
points, even though are expressed, may not be evident on the e/e red or yellow dog, as the tan points are
usually the same color as the dog's coat.

The placement of white areas on the coat are controlled by the S and T Loci

The genes located on the S Locus are very important genes to the Coolie breeder, especially those that
breed merle to merle.

The S Locus is responsible for white spotting, no matter what other genes are being expressed and carried
(hidden), including the merle pattern. If the breeder is having too much white being produced, even though
the dog and bitch being used do not have much white on them, by understanding the genes responsible for
"adding" white, a breeder will know how to breed accordingly. Even though a dog may have very little white
on him, he may be carrying a gene that encodes for lots of white. When bred to another dog with these same
genes, the breeder usually gets a surprise with puppies having lots of white on them. Sometimes, if too much
white is being produced on the offspring and parents are being used that do not have white, or have very
minimal amount of white, using a different sire with that bitch sometimes alleviates the "too much white"
problem. (Pictures are located on the pages labeled by the gene name). These genes are in order of
dominance (from most to least).

The first gene is the
"Self" gene (S) - this gene is responsible for solid color and is dominant over the rest of
the genes. The chest spot and white under belly have been found to be caused by two different genes. The
chest spot is dominant over the white under belly pattern (coloration). A dog that is solid color or solid color
with white on the toe tips, could be carrying any of the other spotting genes. And when bred to another dog
with the same gene combination, could produce puppies without any white, very little white, or lots of white.

The second gene is the
"Irish" spotting gene (s^i) - this gene is responsible for white on the feet, neck, and
tail tip. There should not be any white on the back between the withers and tail.

The third gene is the
"piebald" spotting gene (s^p) - this gene is responsible for white being on 50% of the
body. There are usually colored spots on the back. If a dog has the piebald pattern, he should not be bred to
another dog with the same pattern, unless you like dogs with that pattern. If a dog is piebald and merle
(spots are merled), he should not be bred to another merle with the same pattern. This mating would surely
produce all white puppies, with some being deaf and possibly blind.

The fourth gene is the
"extreme piebald" spotting gene (s^w) - this gene is responsible for a dog being
100% white and white with only a colored head and usually a colored spot over the loins. Deafness and
blindness is associated with this spotting pattern. Not every dog that is the extreme piebald pattern will be
blind or deaf. A person would not want to breed a dog with this pattern to a merle and surely not to a double
merle. Australian Cattle Dogs, Stumpy Tailed Cattle Dogs, Dalmatians are this spotting pattern. They also
have the ticking gene. This is why they are whelped white and color out a few weeks later.

Ticking Gene (T) - is responsible for the ticks, flecks, roaning coloration found in many dog breeds,
including the Coolie. The ticking gene is expressed only in areas that are made white by the spotting genes.
The ticks, flecks, roaning color is the color that the coat would have been, if it weren't white.


The M Locus controls the dilution of the dog's coat in a patchy pattern of dilute and normal color. It is an
intermixed or patchy pattern of various dark and light areas of color on the coat. Merle does not affect the tan

There is a theory that Merle has two related patterns:

Harlequin: This gene is seen in the Great Dane. There is an additional merle modifying dominant gene that
turns the lighter patched areas white. It is believed that when the allelic pair is homozygous, it is an
embryonic lethal.

Tweed: This gene is seen in Australian Shepherds and appears to be expressed in the Coolie. There is
another additional merle modifying dominant gene that makes the light areas have different intensities.

Under the influence of the merle gene, a black coat becomes gray patched with black and a brown coat
becomes dilute red patched with brown.
In adult dogs it is difficult to distinguish sable merles from non-merle sables. The Merle pattern is clearly
visible at birth but fades with age.

Merle (M) (as well as Spotting [S]) results from genes affecting the melanocytes' migratory pathways which
have provided the "wrong" signal or which have interpreted the signal incorrectly due to a mutation.

Merle acts as a "minus" modifier (meaning it 'takes away color') for alleles of the "S" Locus (Spotting).

Merle is an example of incomplete dominance. This means it has intermediate expression:

"M/M" - Homozygous or Double Merle alleles produces almost white dogs: These dogs have more white
than is normal for the breed (they are almost all white). They may also have hearing losses and/or vision
problems. If "M/M" is present, along with the spotting gene, these physical problems seem to be much
worse.  When breeding merle to merle if any of the offspring are non-merle, then neither parent is a
homozygous (double) merle.  It is much better to breed a merle to a non-merle to avoid producing puppies
with impairments.  If a person is set on breeding merle to merle, then is it safer to breed a self merle to self
merle.  A self merle is a dog with base color + merle pattern and does not have any white on them (they
could, however; carry the irish, piebald, or extreme piebald alleles).

** NOTE:  The homozygous merles that are almost all white or have much white is due to the "doubling"
effect of the merle genes on the Spotting genes (irish, piebald or extreme piebald).  Deafness and vision
impairments are thus caused by the LACK of pigment (white) and are not solely caused by the effects of the
merle dilution gene in the homozygous form.  

"M/m" - Merle, carrying non-merle. Merle pattern and the eyes can be blue or marbled (brown and blue
segments in the eyes).

"m/m" - non-merle - Normal color - Non- merle.

Cryptic or phantom (as it's sometimes called) merles are dogs which carry a merle gene but are
phenotypically (look like) tri, bi or self colored. These dogs will have some small area of merling somewhere,
usually a tiny patch of merle pattern on their ear, tail, top of head, etc. Keep in mind the tiny patch can be only
one hair and it can be located anywhere on the body. Cryptic merles are very rare. AGAIN, a cryptic or
visible merle can only be produced when one or both parents are merles.

An interesting theory is that merle is a "fragile" gene that easily allows the merle (M) gene to
mutate back into the non-merle (m/m) gene. This "fragility" may be caused by a transposon, which
is a small mobile "parasite" DNA element similar to a virus. Rather than infecting other animals, the
transposon infects the host's offspring.

Much mammalian DNA consists of inactive "dead" (mutated) transposons, which are found in
nearly all animals. Active transposons are a major cause of mutations. Transposons can move
around. When they "jump into" a gene they can disrupt its function.

The transposon responsible for merle is called "non-replicative," meaning that when it "jumps
out" of a location function may be restored to its host gene. More often, the transposon excises
sloppily and leaves an irreparably damaged gene behind. If the transposon excises cleanly in a
cell that goes on to become a sperm or ova, offspring conceived from that germ cell will revert to

The coat pattern of merles (M/m) would occur as some clonal descendants would be from
migrating melanocytes which reverted from (M/m) to (m/m) as they migrated to their final location
in the skin, producing black patches, while other clonal descendents from other migrating
melanocytes would have remained (M/m), producing the lighter patches.

This theory also explains why occasionally a double merle (M/M) bred to black can produce a
black puppy. When this occurs the mutation most likely occurred in a germ cell. Of course, this
solid black puppy can also be (Mm) genetically but have such large patches of black that merling
patches are hidden. ~~ Erick Conrad
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