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Rat Terrier Colors
Rat Terrier Color Genetics
There are numerous different genes that determine coat color & pattern in dogs, and to further complicate matters, most of the genes have several different alleles which more specifically determine color/pattern.  I will touch on the basics and list some of the genes & alleles that influence color in rat terriers.  Keep in mind that dogs have two of each of the genes in each series--one inherited from their dam & one from their sire.  I have gathered photographs to illustrate many of the colors & patterns our wonderful rat terriers come in.  The term "tri" refers to a dog with tan points on their face, such as a black tri or blue tri, and "bi" is a dog without tan points such as a black bi or blue bi.

The Agouti or "A" Gene Series:
"A" is dominant black, "ay" is responsible for our tan sable dogs, and "at" is responsible for our tricolor dogs (black tri unless that color is changed by the action of another gene)
"A" is dominant to "ay" & "at" and "ay" is dominant to "at".
Examples:
"at at" black tri
"ay at" tan sable
"ay ay" tan sable
"A at" black bi
"A ay" black bi

The "B" Series:
"B" is dominant and means the dog has the ability to form black pigment.
"b" is recessive. In a double dose "bb" results in our chocolate rat terriers.
Examples:
"atat BB" black tri
"atat Bb" black tri that carries chocolate
"atat bb" chocolate tri

The Albino or "C" Series:
"C" is dominant and allows melanin to be formed (allows the formation of color)
"cch" is responsible for apricot & lemon (usually in combination with "ay" but also with "ee")
There are believed to be several other "c" alleles responsible for varying degrees of albinism.

The Dilution or "D" Series:
"D" is dominant and allows intense pigmentation.
"d" is recessive and in double dose dilutes black pigment to blue.  In combination with "bb" the result is our "pearl" color rat terriers.
Examples:
"Aat BB dd" Blue bi
"Aat bb dd" Pearl bi
"atat bb dd" Pearl tri
"Aat Bb Dd" Black bi who carries both the chocolate and blue gene.

The Extension or "E" Series:
This series controls extension & restriction of black pigment.  "E" permits black pigment to be formed in the coat whereas recessive "e" (in double dose) restricts black pigment in the coat.  "ebr" is responsible for the brindle pattern.

The Spotting or "S" Series:
"S" is responsible for solid colored dogs with no (or tiny amounts) of white.
"si" is the Irish Spotting pattern (where the dog has more color than white and the white is restricted to the face, chest, legs/feet)
"sp" is the Piebald pattern (varying amount/sizes of colored spots on white)
"sw" is extreme white.  In double dose this will result in an all white dog or white dog with very little color...maybe just a spot on the eye or ear...if there are plus modifiers present.  Plus or minus modifiers determine the appearance...
Example: "spsw" with plus modifiers would be a more spotted piebald looking dog while "spsw" with minus modifiers would be a mostly white dog.

The Ticking or "T" Series:
(Ticking refers to the small flecks/spots of color that may not be present at birth but often develop more & more over the months & years)
"T" is dominant and means the dog will have ticking.
"t" is recessive, so in double dose it would prevent a dog from having ticking.
Many rat terriers have ticking but it can vary from a few "freckles" on their legs to flecks all over their body.

I hope this information is helpful...the study of canine color genetics is an ongoing and ever-evolving process.  There are still some gray areas and controversy among experts but I have tried to limit the info here to the theories most commonly accepted by genetecists and long time breeders.  I've been studying canine genetics for a few years...reading all I can, learning from others who have been studying for years...but of course there is always more to learn!

***I want to say a huge THANK YOU to the breeders who sent me photos to use as examples.  They are:
Tracey Kallas, K2 Rat Terriers, photo #'s 5,6,14,15,29-32,34-36,40,41

Lynette Ray, Raydiant Rat Terriers, photo #'s 13,16,22,33,37-39

Lisa Sands, Southern Sands Rat Terriers, photo #'s 12,24-28,42

Theresa ("T")Baker, RatPiT Kennels, photo #'s 17 & 18(Taken by Ruthie...Tigger & Belle's mom)

Thank you ladies!!!
Date(s): August 8, 2003. Album by Shawspaws. 1 - 43 of 43 Total. 357 Visits.
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Black Tri...this is probably the most common color...
this is my girl, Chloe, who is a black tri in the piebald pattern (lots of white with a varying amount of spots of color).  Chloe is "at at".  She had a blue grandparent and we found out after her first litter with Lucky that she did indeed inherit a "d"...in that litter we had one blue tri, three black tri, and one black bi pup.

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Black Tri...this is a pup from Chloe's last litter.

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Black Tri...nice closeup....this boy has distinct tan points
but the extent of the tan points on a "tri" can vary...sometimes it's just a tiny dot of tan above the eyes and on the cheeks.

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Black Tri boy from Chloe's second litter.

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Black Tri...this girl is a stunning example of a black tri
in the Tuxedo pattern.

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Black Tri Tux...front shot.

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Black Bi...this is my boy, Lucky.
Bi color dogs carry the "A" gene and do not have any tan points.  Lucky is "A at" and can produce pups with tan points when bred to a female who also carries "at".  Lucky's sire is a Blue Bi so Lucky carries a "d" and can produce blue pups when bred to a female with a "d".
Lucky's dam is a chocolate tri, so Lucky also carries a "b" and could have produced chocolate pups if bred to a female who also carried a "b".


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Black Bi...another picture of Lucky.

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Black Bi...this girl is from Lucky & Chloe's 2nd litter.

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Chocolate Tri...chocolates come in varying shades...
from light milk chocolate to dark liver chocolate (shown here) to very reddish chocolates...but to be a chocolate they MUST have a self colored (chocolate) nose!

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Chocolate Tri...a full body picture of this girl...
she is a chocolate tri in the common piebald pattern.

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Chocolate Tri...another beautiful example
of a chocolate tri (piebald)...this girl is a tad lighter shade of chocolate.

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Chocolate Bi...this is an example of a
chocolate bi in the IRISH SPOTTING pattern (white is restricted to the face, chest, feet/legs)  This girl's irish spotting pattern is commonly referred to as TUXEDO.

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Chocolate Bi...another example...
there are many beautiful shades of chocolate!

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Chocolate Bi

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Chocolate Bi...notice the reddish tint...this color is
commonly referred to as "high red chocolate".  There are tan sables with the same coloration but the KEY to distinguishing between them is that ALL chocolates will have a self colored (chocolate) nose and tan sables will have a black nose.  Completely different genetics at work behind these two colors even though they look so similar!

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Chocolate Bi...a beautiful example of a
"High red chocolate sable" in the piebald pattern...the next picture is a full body shot of her.

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A great shot of the chocolate girl from previous picture!

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Blue Tri...it's hard to tell in pictures,
but blue dogs have blue/gray noses as well.  This is because the gene ("d") that causes this color does so by diluting ALL black pigment to BLUE.  A dog must inherit a "d" from BOTH parents to be blue...in other words, it is a RECESSIVE color.  Dogs with two "d"'s are DILUTES and should never be bred to another dilute (see explanation under pictures of "Pearl")  This is a pup I bred...the mother is a black tri and the father is a black bi...both of them carried a single recessive "d" and this pup inherited that "d" from each of them.

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Blue Tri...another pup I bred here...
this girl has an all white body (with some ticking) and a blue head with tan points.

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Blue Bi...this is a 6 month old pup from my
last litter...same blue coloring, but somewhat different genetics behind the bi colors.

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Blue Bi...another gorgeous example.

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Chocolate tri, Black bi, Black tri, & Tan sable (left-->rt.)
Notice how this tan sable boy has very little of the sabling effect...but as a pup he had noticeably more.
Tan sables come in a variety of shades...from very light tan to deep, red shades that look similar to high red chocolates (remember the color of the nose leather is key!)


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Tan sable...a beautiful example of this color/pattern...
Tan describes the color and sable refers to a pattern (black hairs interspersed that often dissapear as a pup grows up...at birth it is common to see the black hairs on the ear tips, face, and down the back but by adulthood these are often unnoticeable)  You can see this girl has some black hairs on her face and the black nose that all tan dogs must have.

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Apricot...the genetics behind this color and lemon
are a bit more complicated.  Apricot looks like a light shade of tan but it is a different gene that causes this coloration...apricot pups are born either white or with very faint markings at birth and then darken up over the next several weeks.  Apricots MUST have a black nose.  The key to distinguishing an apricot from a light tan sable is knowing what they looked like at birth.

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Apricot...another shot of this boy's handsome face.

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Apricot--this handsome boy is apricot & white like his dad,
Dango.

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Apricot--this apricot girl is a good example of
heavy TICKING.  Look closely and you will see the small flecks of apricot all over her coat...they are easiest to see on her legs.

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Lemon...newborn photo of a lemon pup...
born white and then he began developing color over the next several weeks...it was unknown at birth whether he would be an apricot or a lemon...when he was a couple of weeks old his nose leather color began to fill in and was a light brown/chocolate shade...indicating he would be lemon.  If his nose was black he would be an apricot.

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Lemon...the same puppy a few weeks later...see the faint
spots of color now?  Apricots and lemons are both the result of the "cch" gene.

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Lemon...here he is as an adult...his spots of color
are very light and his nose leather is a light brown color ("self-colored")

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Lemon...another picture of this nice boy.

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Pearl...this color is a
combination of "d" genes that dilute black to blue, and "b" genes which are present in double dose in chocolate dogs.  Because Pearl colored dogs carry a double dose of "d" they are DILUTES and should never be bred to another dilute because of the increased risk of CDA (color dilution alopecia)...a devastating condition that causes extreme hair loss and discomfort. There have been dilute-to-dilute breedings that resulted in healthy litters, but such breedings put puppies at an increased risk of developing CDA at some point. Pearls are currently lumped together as "blue fawns" by UKC, but they are genetically very different and most likely these two colors will be separated and renamed in the future.

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Pearl...this cute pup is a Pearl Tri...
her color is a bit darker than the previous picture, but still noticeably different than blue.  Notice the chocolate/brownish tint to the coat in combination with blue.

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Pearl Bi pup
Pearl dogs are born this color, unlike blue fawn pups who typically lose the blue overtones (blue sabling) of their coat as they mature.

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Pearl bi...here is the pup from the previous picture...
as an adult.

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Pearl...this is one of my "grandbabies"!
Pearl dogs have a self-colored nose that has the same chocolate tint/blue combination as their coat...perhaps best described as "mauve". It is a lighter/more washed out color than a blue dog's nose...just as the coat color is.

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Pearl adult next to a blue pup...
see the difference in the color?

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A pearl and a blue pup...it's easy to see the difference
when they're side by side (or on top of each other !)

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Blue fawn...this pup is a great example of this color...
it is a tan shade with a bluish cast to it...and that's because these dogs are Tan Sables who also happen to have inherited a double dose of "d" which is diluting their black sabling to blue sabling and diluting their nose leather to a bluish/gray shade as well (demonstrated in next picture).  These dogs may appear to have quite a bit of blue to them at birth and then (just like regular tan sables) as they mature they tend to lose more and more of the sabling effect.  As an adult they often look very similar to other tan sables, but there is always a distinct difference in the color of the nose leather.  Because these dogs have a double dose of "d" they are DILUTES.

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Blue fawn pup next to a black bi pup...
see the noticeable difference in the color of the nose leather?

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Blue fawn...this handsome guy is a great example of the
color of blue fawn at adulthood...he looks very close to a tan sable, but with diluted sabling around his face and of his nose leather.

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This picture is to demonstrate the Brindle pattern...
again, brindle is a pattern, not a color...it gives a striped appearance kind of similar to a tabby cat.  This dog is a blue brindle.  Brindle is not an acceptable pattern for UKC registered rat terriers and most breeders avoid it.  The gene that causes the brindle pattern is dominant and it is very difficult to get it out of a breeding program once it is introduced...the girl pictured here is a rescued rat terrier that was in a shelter.

 
   
 
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