Genetics in Canines

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Let me start by saying that I will attempt to explain the known and sometimes unexplained genetics in the dog world.

I am by no means an expert nor do I proclaim to be.  I do however have a very curious nature where genetics are concerned and have researched countless hours the RESEARCHED genetics of dogs.  There are without doubt numerous websites that have been posted on the genetics of canines and I have found more than I care to acknowledge that are INACCURATE. 

 I will do my best to explain genetics in a way that those of you just learning or curious can understand. 

You will find that genes are placed in different categories in my attempt to explain both the gene sequence they are on and the way they affect the genes structure and make up.

It is VERY IMPORTANT to also acknowledge that dogs are not all equal in Gene make-up. 

Some breeds are affected by genes associated with their breed or a few other breeds while some are affected by totally different ones.   Case in point being that a breed affected by a mutation gene will be different than a breed affected by a dilution or acid protein gene.  I guess what I'm trying to say is that while one dog may APPEAR to be BLUE, it's genetic make-up may not always be the same.  This also holds true for genes that affect Patterns and diseases.

 

Coat colours in canines have many natural phenotypic variants.

Some of the genes and alleles involved also cause genetic developmental defects

 

What I have below is for what is TRUE IF the dog is GENETICALLY programmed for the sequence described.

Be Advised:

Just because a dog is said to be a certain color or pattern by an Individual, Group, Club, Registry or Breed Standard does not mean that dog/breed is

 genetically what it is being called.  I live with the motto here of 'Ignorance is Bliss'. 

I can give many 'Case in Points' such as:

1.  The Yorkie is said to be Blue but in reality it is a BLACK and those that do turn blue are from a 'greying' gene that affects their coats.  They are

           in reality NOT Blue by genetics but by Appearance.

2.  Many of the HERDING breeds are called 'Blue Merles' when in reality they are 'BLACK' with grey areas that were diluted by the MERLE gene.  The

          areas are 'GREY' and not blue but somewhere along the line somebody took it upon themselves to call them Blue Merles and others simply followed

          suit.

3.  Dachshunds are said to be 'Dapple' in pattern.  Dapple doesn't actually exist in the Genetic world.  What is being called Dapple is actually the

          'Merle' gene thus should by all intense purpose and reasons be called "Merle" but somewhere along the line was that person who deemed to call it      

          dapple and once again others simply followed.

4.   The gene that many describe as "Parti" - once again doesn't exist.  The gene is the 'Piebald' gene and as before, somebody took it upon themselves to   

         give it a different name, most likely through ignorance and others followed.

5.  Then we also have some out there who call the 'Piebald' pattern in their breed 'Tri".  I still ask myself what is wrong with 'Piebald'?  It is the CORRECT

term for the pattern on which the dog exhibits. 

 

6.  Heaven forbid that we try to get RED and BROWN in proper categories.   There are numerous breeds where the dogs are genetically Reds and

being called Browns and just as many where the Browns are being called Reds.  What is wrong with labeling the dogs and the dogs within a

breed what they actually are even if that requires a BREED STANDARD change and education of those breeding these dogs.  It's a color and

there is nothing wrong with a dog being either color so why not label it properly.  We know these breed clubs love changing the Standard so for once why don't they

          trying changing it to the CORRECT instead of taking out colors and patterns that do exist in the breed.

7.  Chocolate - doesn't exist folks!!!!!  The genetic term is BROWN.  For some reason the dog world has gotten hung up on food for labeling colors of

the dogs within their breeds.  I.E. - Apricot, Lemon, Chocolate, Cream ... etc.  Some of these colors do exist as labeled by genetics by many are just

          fabrications of the uneducated who some how got others to follow.  You've got Chocolate Labs, Chocolate Dachshunds, Chocolate Rat Terriers -

NONE of which genetically exist.  These dogs are BROWN.

8.  Liver - again doesn't exist folks!!!!  The genetic term again is BROWN.  Dogs do not have Liver noses - They have BROWN noses.  Dogs are not

liver colored but are BROWN.   Liver Pointers are BROWN.

 

If I told you I had a black/white/tan dog, depending on who you are and what pops into your mind

          would determine what you would interpret my dog as looking like.  I've had some tell me it would be a black dog with white spots and tan on it.  I've

had some tell me it would be a white dog with black spots and tan on it.  I've had some tell me it would be a black dog with white feet and tan eye brows.  I even had one guy tell me it would be a black/tan dog with a white strip on it's face and I can only assume that is the way they describe a dog of such color and markings in the breed he is associated with.  Well I personally would have 'NO IDEA' of what the dog looks like as I live by GENETIC CODE and ESTABLISHED GENETIC colors

          and patterns.  If you were to tell me you had a Black/Tan Piebald dog then I would without doubt know (*assuming you are educated in proper

          colors and patterns)  that you had a white base coated dog with black spots and tan points.  If you told me you had a Black/Tan dog then I would

know (*assuming again you knew what you were talking about) that you had a Black dog with Tan Points and white markings somewhere on face,

          feet, legs, belly and/or tail. 

         If you were to tell me you had a "Blue Merle" dog then the first thing I'm going to ask is what color is it's nose as it seems

even those who live in the Merle world have found it possible to use the term Merle but not be able to associate it with the proper color for their dog.

  

I asked once who did the Rat Terrier Standard and how they determined the colors and patterns that they made acceptable for the breed.  I was told

          that it was written by a small group and was given one of the ladies names.  I contacted her and asked her 'How the group determined 'lemon'.  I

was told it was because they looked like the Lemon Pointer.  Well of course, how stupid of me not to realize that our breeds should be labeled

         according to other breeds who are already labeled wrong themselves.    You'll have to excuse me if I have little to no use for Breed Standards that

were made up by a group of folks who hadn't the faintest idea what they were doing to begin with and were simply following others mistakes.  Then

          when you take into consideration that those breed standards change according to what group has the most votes at the time, it leaves me with little

to no respect for both the Breed Clubs and the registry that allows such blatant disregard for those who have tried to follow the breed standard and

         find that their Breed Standard dog of today is NOT breed standard tomorrow simply because SOME have the time and audacity to think they have

the right to dictate to those who have better things to do than try to ruin others breeding programs.  If you want to change a breed standard because

          a health issue exist that can't be corrected or at least acknowledged in some other way then by all means please do so but when it comes to a color

that simply exist on a dog but isn't PREFERRED by a majority voting group then I highly recommend you find another group and another registry

          that has more RESPECT for ALL of those registering with them instead of just those who prefer to spend time in meetings to see how they can

discredit fellow breeders.

 

LOCI 

locus (plural loci) is a fixed position on a chromosome such as the position of a biomarker that may be occupied by one or more genes

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Agouti, Red, Sable - "A"

 

BLACK - "B"

                               The gene at the B locus in dogs is Tyrosinase Related Protein 1 (TYRP1).

 

       

Albino - "C"

 

       Dilution - "D"   Blue & Fawn

 

Extension - "E"

 

        Greying - "G"  Yorkies from black at birth to blue.

 

Merle - "M"

 

         Roaning - "R"

       S - White or White spotting

            Affects how much white, if any, a dog will have on it at the S-locus.  See "White" below for variations/degrees at the S-locus.

Ticking - "T"

Allele

A variant of the DNA sequence at a given locus is called an allele.

An allele is an alternative form of a gene (one member of a pair) that is located at a specific position on a specific chromosome.

Organisms have two alleles for each trait.

An allele is a viable DNA (deoxyribonucleic acid) coding that occupies a given locus (position) on a chromosome.

Different alleles produce variation in inherited characteristics such as hair and eye color.

 In an individual, one form of the allele (the dominant one) may be expressed more than another form (the recessive one).

Alleles are forms of the same gene with small differences in their sequence of DNA bases. These small differences contribute to each dog’s unique physical features.
 

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Breed I have only included the breeds which I have been involved in as they are the ones that I have researched.	BROWN and terms (*description, color) used in place of Brown   Keep in mind that these are BROWN dogs and SHOULD be correctly called, described and data based as BROWN.  Unfortunately we have had to many unknowledgeable, lay-person in control of our breed clubs and over the description of our dogs.  Unfortunately we also have registries who have for one reason or another NOT made the proper corrections and backed them so that dogs are labeled as to their genetic make-up.	Alleles Present
Rat Terrier	INCORRECT:                                                           PROPER TERM:      Chocolate, Liver                                                                    Brown
Miniature Pinscher	INCORRECT:                                                           PROPER TERM:      Chocolate                                                                              Brown        Tan                                                                                Blue-Fawn
Harlequin Pinscher	INCORRECT:                                                           PROPER TERM:      Standard is written for correct term                                        Brown
Yorkshire Terrier	INCORRECT:                                                           PROPER TERM:      Chocolate, Liver                                                                    Brown          Blue                                                                                   Black or black/grey
Biewer Yorkie	INCORRECT:                                                           PROPER TERM:      Chocolate, Liver                                                                    Brown           Blue                                                                            Black or black/grey
Dachshund	INCORRECT:                                                           PROPER TERM:      Chocolate                                                                              Brown	bs, bd
Schnauzer	INCORRECT:                                                           PROPER TERM:      Chocolate, Liver                                                                    Brown

• *Note of Interest:
• Brown dogs have been documented and paintings made of brown dogs as early as 1440.
• In early development Brown was seen more in bird dogs than other types.

Chinchilla Allele - C allele - c^ch

 

     "E"

 

"E^m"

 

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COAT

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"C"

     Coat length allele is C for the smooth coat and is dominate.

 

"c"

     For the long coat the allele is c and it is recessive.

 

Smooth coat can have C/C or C/c but a long coat can only have 2 alleles alike c/c.

2 smoothes can produce C/C, C/c, and c/c.  2 Longs can only produce long c/c as they have no "C" to give their offspring.

The gene "FGF5" is responsible for whether a dog has a long coat (rough or fluffy), or a short (smooth) coat.

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RECESSIVE vs DOMINANCE

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          DOMINANCE:

                    Dominance is where the dogs has 2 of the same genes or has a gene that overpowers the other gene if they are

                    not matched thus making the more dominant gene appear in appearance.  There are many dominant genes such

          as floppy ears, long legs, smooth coat, Merle, Brindle ... etc so if these are not desirable traits in your breed then you should not be

          using dogs with such obvious undesirable traits in your breeding program.  A Dominant gene is VISUAL in appearance.

          RECESSIVE:

When someone speaks of a genetic abnormality being "carried" by a dog, they mean that the

gene is there, but it is recessive.  It is basically secretly hidden awaiting a mate to show itself.   Unless we have some test for the gene itself, we cannot tell just by looking at the carrier that it is any different from an individual with two normal copies of the gene. Unfortunately, lacking such a test, the carrier will go undetected and inevitably pass the mutant allele to some of its progeny. Every dog carries a few such dark secrets in its genetic sequence.   Examples of recessive genes are Long coat, short legs, erect ears, tan points and piebald.

 

Eumelanin and/or Phaeomelanin

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Coat colours in mammals depend on skin and hair pigment synthesis. Melanocytes manufacture two types of melanin: the black/brown photo-protective eumelanin pigment, and the red-yellow cytotoxic phaeomelanin pigment. Several paracrine factors secreted primarily by surrounding keratinocytes are involved in the melanogenic pathway by stimulating the switch between phaeomelanin and eumelanin . In this pathway, microphthalmia transcription factor (MITF) plays a central role by regulating the expression of the TYR (Tyrosinase), TRP-1 (Tyrosine Related Protein) and DCT (Dopachrome Tautomerase) genes that encode enzymes involved in pigment manufacture.

Eumelanin - Black, Brown and Blue Pigmentation

Phaeomelanin - Pale cream through shades of yellow, tan and red to mahogany Pigmentation

 

 

Light BLUE or CHARCOAL GREY - "d/d"

Blue or charcoal grey, as a dilution of black, has recently been shown to be caused by the melanophilin gene (MLPH).

Both eumelanin and phaeomelanin are affected in dogs of "d/d" genotype.

Affects the pigmentation in the nose, eye rims and paw pads to a dilution of Blue or Charcoal Grey as well.

These dogs are born blue and charcoal grey in color.  (*Please do not confuse "Born Blue Disease" with Blue born puppies.)

 

INTENSE - "I"

I for Intense that dilutes only phaeomelanin.

Diluted phaeomelanin colors are sometimes called crème, buff, apricot, lemon, etc.

Such a gene, undoubtedly exists. However this gene has not yet been identified or even mapped in the dog.

 

BROWN - "b/b"

Brown is created by a modification of eumelanin.

 It is NOT a dilution of black as many unknowledgeable websites claim.

The gene for brown is TYRP1 and the 3 mutations causing brown are now known

Brown is a type of eumelanin pigment.

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GENES

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Genes are made up of DNA. Each chromosome contains many genes.

A gene is the basic physical and functional unit of heredity. Genes, which are made up of DNA, act as instructions to make  molecules called proteins. Every canine has two copies of each gene, one inherited from each parent. Most genes are the same in all dogs, but a small number of genes are slightly different between breeds. Genes are made up of DNA. Each chromosome contains many genes. A gene, lets say White (*W) is usually, (*but not always) named for the first mutant allele discovered and then subsequent versions  of the same gene are given variations of the first such as w+. we.   So when you see symbols associated with a letter you know that it is a variation of the original gene.

 

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DILUTION GENES

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Tyrosinase Related Protein 2 (TRYP2) - SLATY GREY

DCT or Dopachrome tautomerase

In several other species, more than one dilution gene has been identified. One of these is thought to be Tyrosinase Related Protein 2 (TRYP2). In mice, this gene dilutes black coat color to slaty grey and another name for the gene is therefore "slaty".

Yet another name, based on it chemical composition, is DCT or Dopachrome tautomerase.

This gene has been mapped to dog chromosome 22. In mice this DCT gene acts as a co-dominant.

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"Dilution" Loci

Locus Symbol	Gene	Action	Named by:	Dog Chromosome
D for dilute	MLPH	eumelanin diluted to grey or blue & phaeomelanin paled	Dr. Little	25
C for color	tyrosinase (TYR)	albinism, dilutes phaeomelanin & eumelanin	Dr. Little	21
P for pink-eyed	P gene	pink eyes & "white" coat	Dr. Little	5
G for greying	???	progressive greying	Dr. Little	?
I for Intense	???	only phaeomelanin diluted	Dr. Sponenberg	-
?	MATP	phaeomelanin diluted as co-dominant, eumelanin as recessive		4
Slaty	TYRP2	eumelanin co-dominant dilution		22

 

          MLPH

• MLPH gene are responsible for the coat color dilution in Pinschers.

 MUTATION

A mutant

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1. The act or process of being altered or changed.

   An alteration or change, as in nature, form, or quality.

    

   A change of the DNA sequence within a gene or chromosome of an organism resulting in the creation of a new character or trait not found in the parental type.

    

   The process by which such a change occurs in a chromosome, either through an alteration in the nucleotide sequence of the DNA coding for a gene or through a change in the physical arrangement of a chromosome.

    

   Mutation refers to any sudden change in DNA—deoxyribonucleic acid, the genetic blueprint for an organism—that creates a change in an organism's appearance, behavior, or health.

Mutation is a change in the structure of the genome by alteration of the DNA. Alterations in the DNA sequence can arise when mistakes made during replication (copying of the DNA) cause the insertion or omission of a base (point mutation) or the removal or inversion of larger segments of DNA. Mutations can also be caused by radiation or by some chemicals (mutagens). The consequences of mutations are variable; if a mutation occurs within a gene then the composition of the gene product (a protein) will be altered and may affect its function.

Mutation is a phenomenon significant to many aspects of life on Earth and is one of the principal means by which evolutionary change takes place. It is the cause of numerous conditions, ranging from albinism to cystic fibrosis to dwarfism. Mutation indicates a response to an outside factor, and the nature of that factor can vary greatly, from environmental influences to drugs to high-energy radiation.

Mutations are normally one time occurrences in the dog world and then systematically reproduced through heredity.

Many mistake recessive carriers that produce non-normal offspring as producing mutants when nothing could be farther from the truth. 

Mutants are caused by a change in the DNA cells and not from combined recessive markers inherited from each parent.

Mutation leads the inexperienced and unknowledgeable to believe that an animal is not of the parentage said or is not of purebred status.

Only DNA testing can say for sure what the lineage is of an animal.

Mutations can occur from structurally sound individuals from a long lineage of excellent quality PURE-BRED animals.

The fact that a mutation has occurred in a color pattern does not make it any less of a quality animal. One should realize when this type of “unusual event” occurs, do not necessarily reach the conclusion that the parents are “not” the parents. Mutations have occurred in all breeds of dogs; some good and some that are not. Furthermore, some affect the animal and some the people. There are many cases of genetic mutation, which has not affected the quality of the animal but may have an affect on the owners of the animal through ignorance and denial heaped on by others. 

None of our dogs or us would be where we are today without genetic mutations!

 

So BEWARE of those who make statements like: "It can't be purebred" or "That doesn't occur in that breed" as you are without doubt listening to somebody who knows little to nothing about genetics.

CHROMOSOMES

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The male normally produces an equal number of sperm with either the X or the Y chromosome. As his mate will only be producing eggs with X chromosomes, an equal number of female (XX) and male (XY) puppies should be produced. Of course chance plays a major role, and litters often don't have a perfect 1:1 ratio.

 

"A" Locus

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"A" - the A-locus is responsible for coat color and in some cases their pattern.

 

"A" - Agouti -  "pattern" locus that allows for the increasing distribution of dark (black or brown, i.e eumelanin) pigment over yellow/red (phaeomelanin) in a recessive manner. Contains 4 know alleles with general dominance established from yellow to black.   Often

incorrectly labeled as Wheaten or Wildboar in some breeds.  This is considered the "Wild Type" gene as it is what makes foxes, raccoons,

Coyotes, & wolves, just to name a few, their color/pattern.

     "a" - recessive black

 

"A^{s" -} produces black without any tan on the dog but the black can be diluted by "E".

 

     "a^y" - Red - The ay allele produces the red coloration most often seen in different breeds.

• a^y in the absence of A^s produces a dog which is predominantly Red (phaeomelanin) sometimes with black tipped hairs or interspersed black hairs.
•  a^y is recessive to A^s, but incompletely dominant to a^t. That is, an a^ya^t dog is on average darker (more black hairs) than an a^ya^y dog. The usual wrong term for this color/pattern combination is "sable" or "Wildboar" in some breeds.    It should be accurately called Red Sable.

             

              These dogs are often born with a darker overlay that fades to a greater or lesser extent with maturity.

               The hairs may be mixed with darker hairs.  This is a pattern over a color.

               A dog with Lassie's sable-and-white coloring would have alleles producing both the Red

              color at the A locus of ayat and the Irish-marked white pattern at the S locus.

Red can have the genotype as/as, as/at, or as/ad.

 

    "at" -  Tan point. The at allele produces dogs with a dark body coat and tan points.

   a^t, present in double dose, produces a dog which is predominantly black, with tan markings on the

    muzzle, over the eyes, on the chest, legs, and under the tail.

             Depending on genes at other locations, these dogs can be black and tan, brown and tan, or

             blue and tan. They can also have various amounts of white on them depending upon interactions

            with genes at the S locus. Tan point dogs can be at/at or at/ad.

    "aw" - Wolf-color

a^w is the wild "wolf-color" and possibly found in some salt-and pepper breeds. It differs from sable in two ways. First, the tan is replaced by a pale cream to pale gray color. Second, the hairs are normally banded - not just the scattering of black-tipped hairs sometimes seen in a sable, but several bands of alternating light and black pigment along the length of the hair.

    "ad" -  Domino. The effect of the ad allele is often hard to distinguish from that of the ay allele.

This is the wild "wolf-color"

               These dogs have a pattern in which dark hairs are tipped with black or brown and are lighter near

               the skin. They also have lighter legs, underside, and face, usually with a widow's peak or mask

               such as that seen in Siberian huskies. they come in a variety of shades and colors. They may be

               combined with varying degrees of white spotting depending on interactions with the S locus. A

              domino dog can only have the genotype ad/ad at this locus.

 

 Little was unable to determine the dominance relationship of this gene, or even to say with certainty that the banding and the reduction of tan pigment were due to the same gene.

     The distribution of colored hairs determined by the A locus is complicated by interaction with

     alleles at the E locus.   

The A locus is responsible for a number of common coat patterns in the dog. 

Expression of all of them requires any combination of two k^y or K^br alleles at the K locus, and at least one E or E^m allele at the E locus. 

The gene involved is the Agouti gene, and variations in it are responsible for:

 fawn and sable dogs (A^y), wild type (A^w), tan points (a^t), and recessive black(a).

B-Locus

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The B locus determines whether dark hairs will be black or brown.

 

        B: Black.- The B allele allows black pigment to be black.

                            Dogs with black pigment may be BB or Bb.

       

brown - "b"

The nose leather, pads, and eye rims are also affected by this gene making them brown or sometimes referred to as self-coloured.

All dogs which have brown coat color have at least one E or E^m allele so that eumelanin is produced.

Brown dogs do NOT occur from dilution of either Red or Black.  Brown is a modification color and not a dilution color.

b: brown.- The b allele makes all black pigment appear brown.

                               Dogs with bb also have brown colored noses, brown eye rims and brown paw pads and usually light-colored eyes.

B: Brown series
This locus does not affect red colors.
 B = black
 b = brown
 

Commonly also known in some breeds as liver, chocolate, sedge, and less frequently, red

 

C-Locus

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The C locus acts on red pigment.

In several species of animals the C locus is considered to be tyrosinase because albinism is caused by mutations at this locus

 

          C:  Full Color. The C allele allows for fully saturated reds.

                               C full color, allows full expression of whatever pigment is prescribed by other genes.

                                         These dogs may be either C/C or C/c.

         c: decreased color. The c allele decreases the intensity of the red or tan pigmentation.

                                    Dilute Red could thus be c/c.

 

        c^{e -} extreme dilution -  This gene may be part of the makeup of some "white" dog breeds where the white color is due to extreme dilution of      

                                            tan. The West Highland White Terrier may be c^ec^eee.

                                             A cross to a black and tan breed would be interesting from the point of view of color genetics.

 

       c^p - platinum, is optically similar to albino but retains very slight tysonase activity and in the mouse is described as retaining some luster

                          in the coat as opposed to the pure white seen in albino. Although there is a total absence of proof one way or the

                         other, hypothetically the white Doberman, with pale blue eyes and pink nose, is due to a homologous gene.

 

c - albino, is not known to occur in the dog as a regular part of any breed color, though possible candidates for mutations to c have been recorded. As mentioned above, the c gene cannot produce working tyrosinase, and a cc individual cannot produce melanin pigment.

Chinchilla Allele - C allele - c^{ch --} allele c^ch of the C locus would pale phaeomelanin to crème and that another

possible allele c^e might dilute phaeomelanin to white in addition to the c^a allele which causes albinism in homozygotes.

 

c^ch, chinchilla or silver, when present in double dose removes most or all of the phaeomelanin pigment with only a slight effect on black pigment.  Black and silver replacing black and tan, or a wolf-like color without the extra banding (see a^w, above) may also be due to a c^chc^ch genotype. Dogs with very light tan probably are c^chc^ch or something similar. Brown dogs show lightening even of eumelanin pigment is thought to be due to a bbc^chc^ch genetic makeup. The possibility of other, rufous modifiers affecting the shade of phaeomelanin pigment needs to be kept in mind, as does the possibility of more than one form of chinchilla in the dog - rabbits are thought to have three.

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As seen from the above, C is known to have a number of different forms and effects. The usual assumption is that dogs have at least one mutant allele, c^ch which when homozygous lightens phaeomelanin (yellow) pigment to cream and more weakly affects brown and longhaired black. A second proposed allele, c^e may be responsible for further reduction of cream to white in some breeds, or modifying alleles may be responsible for the further lightening in these cases. Some forms of C can modify eye pigment causing Blue eyes.

C: Color series
 C = full color
 c^ch = chinchilla, lightens red colors into cream, does not affect black pigment
 c^e = extreme dilution, red becomes nearly white but the nose and eyes stay dark
 c^b = blue eyed albino, gives pale blue eyes
 

D-Locus

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The D locus acts in a similar manner as the B locus but determines if dark pigment will be black or blue

     D: Dark. - DOMINANT -  The D allele allows black pigment to be black.

                        Dogs with black pigment may be DD or Dd.

     d: Dilute - RECESSIVE -  The d allele makes all black pigment appear gray/blue.

                        Dogs with d/d also have slightly lighter-colored noses, eye rims and paw pads.

              NOTE: Affects skin/hair color simultaneously

 

• Note, dogs with both bb and dd have a diluted red color with blue or brown noses.

D affects both eumelanin and Phaeomelanin pigment. It is thought to act by causing the clumping of pigment granules in the hair. Like B, it often affects skin and eye color, and some breeders has mistakenly been associating dd with skin problems which is not true.  The skin problems often seen in Blue and Fawn dogs is present in dogs of other colors as well.  It is NOT a blue or fawn hair issue but one that affects the follicles and can do so in any color.  The problem being a RECESSIVE gene of the BLOODLINE and not of a given color or dilution factor. 

"If a solid brown dog also is dd, the result is the silvery color seen in the Weimararner and known as "fawn" in Dobermans.

While dd acting on black or brown is a part of the genotype of several breeds, dd acting on Red/Yellow is relatively rare.

The action of dd on phaeomelanin has been described as a flattening or dulling of color.

D: Dilution series
 D = intensive pigment
 d = dilution, dilutes black into blue and brown into fawn.
 

E-Locus

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Works in connections with the A-Locus

 

The distribution of colored hairs determined by the A locus is complicated by interaction with alleles at the E locus.

Its alleles have the following effects:

         Em: Mask. This allele adds a dark mask.

                              Black- or chocolate-masked dogs can have the genotypes Em/Em, Em/E, Em/ebr, or Em/e.

        E: Extension. This allows the formation of whatever pattern is determined at the A locus.

                       E, normal extension of black, allows the A-series alleles to show through with no masking or brindling.

                      It is apparently recessive to both E^m and E^br.

                                These dogs can have the genotypes E/E, E/ebr, or E/e.

 

        ebr: Brindle. The ebr allele produces dogs with irregular, vertical dark stripes running down the

                                 sides of the body over a lighter background.

                       Brindle in dogs consists of black, vertical stripes on a sable/fawn background, usually rather soft-edged,

                       but much more regular that a typical Japanese brindle, and showing no tendency for the tan and black patches

                       to become more distinct in the presence of white spotting genes. Genes that affect eumelanin will affect the dark

                       stripes, so a bb brindle, for instance, will have brown rather than black stripes. Brindle on a black and tan will

                       show only in the tan areas, while brindle on a black cannot be distinguished at all. If in fact recessive red (ee) is

                       in the same series with brindle, it is not possible for brindle (or mask) to occur on an ee dog as one of the E genes

                      would have to be E^br (or E^m), leaving no room for ee. Some research implies that brindle and mask were co-dominant, with

                      masked brindles being E^brE^m, in which case masked brindle could not breed true.

                                Brindle dogs are either ebr/ebr or ebr/e.

 

     e: Restriction - Recessive. Dogs with two e alleles have no black hairs on their body, no matter what the

                              alleles at the A locus dictate. Examples are Crèmes that are e/e.  Keep in mind that Crèmes can also be c^ch on the C locus.

                              e, recessive red, overrides whatever gene is present at the A locus to produce a dog which shows only phaeomelanin pigment 

                             in the coat. Skin and eye color show apparently normal eumelanin, although some ee dogs appear to show reduced pigment on

                             the nose. In a few breeds "reds" may be either a^ya^y or ee, and crossing the two can produce unexpected blacks.

                             These crème dogs from the E-Locus must be e/e.

 

The Miniature Schnauzer is a breed in which the "e/e" dogs appear white or "silver". . Note that the classic black-and-tan pattern caused by an "at/at" genotype at the agouti locus is called black-and-silver in this breed.  It would seem that all Phaeomelanin pigmentation is diluted to a white or silver in Miniature Schnauzers.

                             

                       Besides the distribution of light and dark hairs determined by the alleles at the S, A, and E loci,

                       the actual hue of color of the darker hairs is influenced by alleles at other loci.

G-LOCUS

Greying

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"G" -  Greying series
 "G" -  the black hairs are graying with age
 "g" -  no greying
 

K-LOCUS

Dominant Black

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"K^{B" -} The dominant allele in the series is K^B, which is responsible for self-coloring, or solid colored

                fur in pigmented areas.

"K^bk" = dominant black (eumelanin) allele.

"k^br" - intermediate "brindle" allele.  Recessives produce brindles and fawns.

"k^y" - recessive (phaeomelanin expression) allele.  This gene allows the expression of the genes at the "A" locus.

 

Note of interest:

 Once was thought to be on the "A": then referred to as Dominate black.

At that time it was said that A is a solid, dark colored coat. A solid black, brown, or gray dog (or a black and- white,

brown-and-white, or gray-and-white dog) without tan points would have at least one A allele.

These dogs were said to have the genotype A/A, A/ay, A/at, or A/ad.

We now know that DOMINANT Black is on the "K" locus.

 

Gene	Expression:
KB KB	self-colored ...  (solid color in pigmented areas)
KB kbr	self-colored ...  (solid color in pigmented areas)
KB ky	self-colored ....  (solid color in pigmented areas)
kbr kbr	allows A locus to express ....  (tan point, tricolor, fawn, sable, tawny) with brindling
kbr ky	allows A locus to express ....  (tan point, tricolor, fawn, sable, tawny) with brindling
ky ky	allows expression of agouti patterns from the A Locus without brindling

M-Locus

Merle

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The merle phenotype is treated as a dominant but is actually a incomplete dominant or a gene with intermediate expression trait, with heterozygous dogs presenting a coat colour in which eumelanic regions are incompletely and irregularly diluted, leaving intensely pigmented patches. Merle is found throughout the body except on the pheomelanic regions of the black and tan coat colour.

The Merle gene has been successfully identified on canine chromosome 10 and located on the "pmel" gene.

 

The merle phenotype is very old, with the merle coat colour being reported in old books from which drawings of merle dogs have been selected and reproduced.

      

mm - Non-merle

 

      Mm - Merle - This is another dilution gene, but instead of diluting the whole coat it causes a patchy dilution, with a coloured coat

                                      becoming patched with a lighter color.  IE. - black to Gray,  blue to lighter blue, Red to lighter Red, Brown to lighter brown.

                            The lighter areas are the actually merling and not the darker areas as many seem to say.

                            Eyes of an Mm dog are sometimes blue or merled (brown and blue segments in the eye

 

MM - Double Merle - Considered to be SEMI-LETHAL as 1/4th of all MM puppies are born dead or have such severe

                                            abnormalities that they die shortly after birth. A MM is a double dilution of the merle gene spotting the same

                                                      area causing that given area to actually turn white.  Thus double merles are a mix of 3 colors.

                                            Double Merles are often confused with the Merle/Piebald combination.

 

                          Merle appears to act as a minus modifier, in addition to its effects on coat color.

          M: Merle series
          homozygote MM -  Double Merle - produces double marked merle areas of white - possible health issues.
          heterozygote, Mm  - Merle
          mm = no merle
 

One parents has to be merle to produce merle offspring as it is not carried recessively.

 

"R"

ROAN

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This may or may not be a true series. It has been suggested that roan may simply be a very fine ticking, with dark hairs

growing in an initially white area of the coat. A second type of roan, in which white hairs develop in an initially dark coat,

could be due to gray or could be a type of roaning different from the progressive development of dark hair in a light area.

 

       RR - ROAN - Dominant to r/r.  It is not clear whether this is full dominance or incomplete dominance.

 

rr - Non-Roan

"S"

WHITE

Solid, Irish, Piebald and Extreme

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White is a pattern and not a color.

White Distribution

  Dogs have four different alleles for different degrees of white spotting. Alleles for more

  white are always recessive to those for less white.

 

     In decreasing order of dominance, the alleles

 

at the S locus are:

 

           S Solid. These dogs have no white on them. A dog without any white must have at lease one

                         copy of the S allele. However, because S could mask the presence of any of the less-dominate

                         alleles also at that locus, such dogs could be either S/S, S/si, S/sp, S/sw.

         si  (*Irish marked). Next in the dominance hierarchy is si, which causes the so-called irish-marked

                       pattern. The feet (and perhaps the legs), tail tip, muzzle, and collar are white. Irish-marked dogs

                       can be either of 3 combinations si/si, si/sp, si/sw.  Most often called 'Tuxedo'.

        sp (*Piebald)  These dogs are predominantly white with patches of color. They can be either sp/sp or sp/sw.

                        These dogs are often times incorrectly called PARTI.

        sw (* Extreme white spotted). These dogs are almost all white, with only small patches of color.

                                                          Because this is the most recessive allele such dogs have 2 copies of it, sw/sw.

       S: Spotting series
       S = no spotting (solid color)

"T"

TICKING

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Where flecks of color develop in areas of white on the dog.

The color of the ticking will be whatever color the dog would of been in that area before the white occurred.

Ticking is affected by other genes which determine is size and shape.

 

     "T" - Ticking - Dominant over non-ticking.

     "t" - Non-ticking

 

The most well known form of ticking would be in the Dalmatian.

 

T: Ticking series
 T = ticking in the white spotted areas
 t = no ticking
 

    Let me first state that what is being called PEARL by some registries is genetically a FAWN which is the same thing as an Isabella Dachshund.  I will use   

         the correct term being FAWN to describe the genetic makeup and what it is.

     Fawn is one of those colors that has most breeders baffled in not only how to describe it but also in how to produce this magnificent color.
     We hope the information and pictures here will help clear up the confusion.

     A FAWN is born with a silvery taupe color to the hair. Noses are a self color of dilute brown. The noses are NEVER blue or dark brown.

     FAWN is derived from a combination of dilute genes and is in actuality a dilute of  brown caused by the blue gene.
     BOTH parents of a fawn must be or carry BOTH brown AND Blue and both parents must give the puppy their brown and blue genes in order

     for the puppy to be a Fawn..

     Breeding dilute to dilute will not cause health issues of itself..  Coat color is ONLY skin deep and it is not the coat color that causes issues but

     the recessive and/or dominant genes that each puppy inherits for the health issue involved..

INBREEDING vs LINE BREEDING vs OUT BREEDING

Inbreeding is the practice of breeding two animals that are related (i.e. have one or more common ancestors). The degree of inbreeding may be assigned a value between 0 and 1, called the inbreeding coefficient, where 0 indicates that the animals have no common ancestors. Inbreeding produces animals that acquire the same allele from both parents as a result of their common ancestry. Thus, it increases number of genes that are homozygous. However, it does not discriminate between good alleles and bad, and therefore is just as likely to make genes homozygous for bad alleles as for good ones.  Inbreeding is normally only considered in dogs through the 7th generation.

Line breeding is a form of inbreeding practiced by some breeders but by a closer relationship than inbreeding.

In Line breeding it would be immediate family members such as Son to Mother, Father to Daughter, and relations

of Grandparents to their own offspring or grand-offspring.  The breeding of Cousins is NOT considered line-breeding.

Out breeding is the form of breeding where no dog would appear twice in a 7 generation ancestry (*pedigree).

There are theories on the benefits and downfalls of each and as far as this author is concerned it is a matter of personal preference and the ability to know your bloodlines.

All 3 have their advantages and disadvantages.  As long as the lines are free of the same undesirable (*bad) dominant and recessive genes, it really makes no difference what their relation is.  If you are breeding a clear

line, even if they are heavily related, you would be better off than breeding two totally unrelated lines that have

bad dominant and/or recessives genes that would be inherited by the offspring thus resulting in undesirable and

often times fatal traits.

I would be remise if I did not point out that every dog is believed to carry 3 to 5 recessive lethal genes thus making it virtually impossible to completely avoid genetic disease.

Recessives - Mutations or Crosses

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There have been dogs of what is called "Off Colour", "Undesirable", "Non-breed standard", "from bad breeding", "Mutts", for centuries

and dogs of these descriptions just keep popping up more and more.  WHY you ask? 

The answer is actually very simple and is one of three things:

 

1.  The dog's ancestry has a recessive gene in it that was there from the beginning and eventually found a mate to travel with

            thus producing an unusual offspring.

                     These should not be called "RARE" as once one has been produced they can be produced again.  If this is the case where it is a

           recessive gene then the gene has been in the gene pool awaiting a-like mate to express itself.  This is not as uncommon as many think as

           in smaller countries more and more 'unusual' offspring are occurring due to the lack of a more versatile and broad gene pool in which to

           breed to.  It is less likely for a broad spread gene pool to experience deep hidden recessive genes than it would be for areas like Russia,

                     England, Estonian and Finland ... etc.   Case in point being the 'Crème' Dachshund from England, the 'Blue' Boxer from Estonian,

                     Finland & Russia, and then you have the Biewer Yorkie with it's 'BELTED' pattern from Germany.

          

 

         2.    A mutation has occurred and one of the genes was altered during fetal development.  Basically this is the same thing as evolution

          where our bodies change to adapt to our environments.  A mutation is "RARE" and seldom happens more than once.  The mutated offspring

                    can then be reproduced through breeding but seldom will 2 totally unrelated dogs produce the same type mutated offspring.

        3.    A cross with another dog either recently or many generations ago.  A recent cross would be cause for concern but if it was many generations ago

               then it could be as purebred as any others.  Purebred status in canines is considered at 7th generation where only a one time cross occurred in

               the first generation and then the offspring were either bred back to each other to form a new breed or the F1 offspring were bred back to only

               a  breed of one of their purebred parents for the next 7 generations to gain Purebred status once again.   Some registries I've noticed are accepting

     dogs for Purebred status at 3rd generation which should be of great concern as there is no way to set a 3rd generation offspring's genes and dilute

               the genes of the undesired parent in 3 generations.  With a 3rd generation cross you could cross 3rd X 3rd and a high percentage of your 

     offspring will take on the characteristics of the undesired breed. 

 

You might want to ask yourself too just "HOW OLD IS MY BREED".  Many breeds are fairly new creations as far as dog development goes.

The Biewer Yorkie, the Mi-Ki, and even the Harlequin Pinscher are newly developed breeds of dogs.

Genes in these breeds will continue to come and go and as more are produced and more breeders use these for breeding there will be

RECESSIVE genes which  will continue to give us "SURPRISES" in the breed.

Even if it is what many would consider an "OLD" breed, you have to ask yourself at what point did it become a "Recognized" breed with a

breed standard, closed gene pool and database registration.  The Rat Terrier is probably one of the oldest breeds we have yet it did not

receive breed recognition until the 1980's and even then there was not a "Closed Gene Pool" and still isn't with a lot of registries.

As long as there are 'Open Registries" you will continue to see the Rat Terrier change with time in both appearance and color/pattern.

The 'Harlequin Pinscher' is a RE-Development of an breed that became extinct in the 50's.  It's lineage is made up of Miniature Pinscher

and the Rat Terrier and as would be expected with any new breed the gene pool is without doubt still in transition.

 

Blue-Fawn

Combo gene of color and pattern that is highly misunderstood

Often wrongly called "TAN" in some breeds

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  Ask somebody what a Blue-Fawn is and you'll get more of a variety of answers than you should.  Blue-Fawn is a fairly simple gene to understand

     and comprehend.  The problem is that you have to want to and accept it and not try to make it into some kind of rare and exotic color such as

many have in the Miniature Pinscher breed trying to say it is a rare and exotic "Tan".  This couldn't be further from the truth and if any of these so-

called experts of the breed and their colors and patterns would have their dogs DNA sequence tested they would soon learn it is a Blue-

Fawn and while lovely it isn't a 'gift sent from above for them to exploit' but a dog of simple genetic make-up and can easily be reproduced by

those with the knowledge and gene pool to do so.

I have a Blue-Fawn and while he is lovely and I'm very proud of him, I am just as proud of my Black/Tan or my Browns and yes even

   my Reds, Blues and basic Fawns.  You see color isn't the MOST important part of breeding.  It is a luxury to have on a QUALITY dog.  That's the part that most breeders miss.  They worry more about color than Quality or even physical health.

 To me a Blue-Fawn has to be on a QUALITY dog in 3

  categories with none taking precedence over the other - 1. Conformation - 2. Temperament - 3. Health.  I simply put Conformation as #1 as it is the first thing that everybody sees.

Temperament is second for the same reason as once you see the dog, it doesn't take long to figure out what it's temperament is.  Then Health rounds out the 3 as it will be a building block for generations to come.  If you already have the first 3 in place then I

see no harm in working on exterior colors and patterns and even on interior colors and patterns that dogs can carry recessively but not be seen from the outside.

 

  A Blue/Fawn is basically a Red dog with Blue dilution.  It has a diluted Red coat of Fawn with blue dilution that

expresses itself in the pigmentation of the skin, in the nose pad and more often than not it will have

intermingling hairs of blue throughout the fawn coat.  It is not uncommon to see a blue ridge of hair down the back

bone on a fawn dog.

"Black Hair Follicular Dysplasia"

Also incorrectly known as "Born Blue Disease" and "Color Dilution Alopecia"