French Bulldog color and pattern genes

French bulldog color genes can be a bit confusing. There are SO many colors and patterns and combinations, it can be a little hard to keep up. Honestly, if you’re not planning to breed it doesn’t even matter! However, it’s sometimes just really cool to know a bit more about your best friend, afterall genetics are fun!

Now all that being said… If you plan on breeding, those letters can make a huge difference in puppy selection or the parents you match with for breeding! I can’t say enough about doing research prior to breeding. I spent months learning about genetics before I was able to settle on what exactly I wanted for my program. I think genetics is one of the coolest things about breeding and it's so interesting to learn about. It doesn’t get any better than pairing two animals that you handpicked based on genes and ending up with even better offspring that was preplanned so you know what to expect.

So, what do these letters mean individually and also when they are paired together? It is important to note that each trait is made up of two letters (alleles), one given by each parent. There are also dominant traits that will be expressed with only one gene passed by one parent and recessive traits that need two genes to be expressed, one from each parent. To make things even more complicated, some genes work with other genes to change the way coat color or patterns are expressed.

In the frenchie world, there are two sides of the fence for owners and breeders... standard colors (colors recognized by the breed club and AKC) and "fad" colors. Fad colors can still be registered by AKC by sending in your photos during registration and them picking a color that closest fits your dog. Your dog will not be able to compete in most shows, but their standing is that they will still register anything with papers showing that is is purebred and they can still be bred and shown in things like agility. My personal love is for the "fad colors" and that is what I breed. Despite a lot of these color purists (people that only breed/have AKC standard colors) that tell people that these "fad" colors are mixed dogs... that's simply not true and a lot of them haven't done their research into the history of the breed. Most of these colors have been in the French Bulldog breed for over 100 years, with the exception of merle. There is picture proof from books found in the library of congress, from old news articles, and ingrus pedigree reports that show these colors, like blue and chocolate, in photos form the late 1800s and early 1900s. In fact, these colors like blue, were winning AKC shows until politics got involved and the fancy bigwigs started losing, and these colors were then disqualified. BUT you can still see these "fad" colors running through champion bloodlines today, through pedigree searches on Ingrus that show these colored puppies being thrown by these standard dogs, backed up with descriptions and sometimes photos. If these colors didn't come from these foundation stock dogs, then why are these dogs throwing color? This includes fluffy french bulldogs, which were then known as angora instead of fluffy, which again you can find and back up with photo proof from at least the 1930s. 

Merle is an exception to this, a lot of people say it was brought in from chihuahuas, which were bred with aussies to make mini or toy aussies. The fact is that once you breed a different dog breed in and then cross it back to whatever breed you started with, by the 5th-7th generation it looks exactly like a pure bred dog again and won't even show up on a DNA test. That's exactly how every breed starts anyway, with a couple breeds being put together to make another breed. This is nothing new and has been going on for hundreds of years. 

These days, there are people bringing in other breeds to the French bulldog for new colors (like pink, which is actually albino), new patterns (like koi and husky) and features like wrinkles and bigger ropes across the nose or no hair (velvets, big ropes, and hairless). I'm not going to be speaking about these brand new colors and patterns because I personally do not have any in my program at this time, and haven't done the research I would have to do to feel comfortable talking about their genetics and how they are made.

The A-locus (Agouti) has three possible options (alleles), Ay – Fawn, At – Tan, a – solid.

Possible Combinations:

• Ay/Ay (2 copies) – Fawn base if Ky/Ky, Black if carries just one brindle gene
• Ay/At (1 copy fawn, 1 copy tan points) – Fawn base if Ky/Ky, Black if carries just one brindle gene, carries Tan Point
• At/At (2 copies) – Tan Point base
• At /a (1 copy tan points, 1 copy solid) – Tan Point base and carries solid
• a/a (2 copies) – Solid, not Fawn, the K-locus doesn’t have an effect

There are four different alleles identified in a dog’s genes that  give the agouti coloration also known as the A locus. These alleles are  “ay”, “aw”, “at”, and “a”. This color is much like that of a rabbit  except “a” which is recessive black and at which is tan point or tri  color. Solid Chocolate French Bulldog. These  alleles are dominant in a chain of command. This means that “ay” is  more dominant than “aw”, “aw” is more dominant than “at”, and “at” is  more dominant than “a”. For example, if a dog is “ay/at”, the color of  the dog will be fawn. However, this is all dependent on whether  the dog carries the dominant black gene K locus or the recessive gene  “e” on the E locus or not. If a dog carries one or both of these genes, the A locus is muted, and the A locus coloration will not appear on the dog. This is because both the K locus and the E locus are dominant over the A locus. The  agouti gene determines the base coat color in dogs that are “ky/ky” for  dominant black. Dogs must be “ky/ky” in order to express any alleles on  the A locus. The color of the dog can still be altered by other  genes, such as by the B locus or D locus, however. For example, if a dog  is “b/b” (testable chocolate), it will be modified to appear as a  chocolate pigment. However, if a dog’s A locus is “ay/at” or  “ay/ay”, and the dog is also “b/b”, the fawn dog will have a chocolate  nose. A dog that is “at/at” will have a chocolate and tan coat. If a dog is n/n for the gene, that means that the dog will not express any coloration associated with this gene.

The  “ay” allele is the most dominant of all four alleles. This gene  produces a range of colors like light fawn colors, darker red colors, or  even sable. Dogs that are “ky/ky” and have two copies of “ay” will  always express the “ay” Fawn coat. This is because the “ay” allele is  more dominant than the “ky” allele. Dogs that have one “ay” and one “at”  will be sable. It is important to know that a dog can appear as fawn or  sable BUT could also carry any other of the three alleles. These other  alleles will never fully express. 

A dog that has two copies of  “ay” will always pass on the “ay” allele. If that dog is bred to another  dog that is n/n (recessive) for the K locus, the dog will always  produce fawn or sable pups.

The  “aw” allele produces a color known as “wild sable.” With this  coloration, the hairs switch pigmentation from a black color(on the  tips) to a reddish or fawn base color. It is recessive only to the  “ay” allele. This also means that it is dominant over the “at” and “a”  alleles and will be expressed before the “at” and “a” alleles.

Both  the black and tan and tricolor are produced by the “at” allele. A  tricolor dog is black and tan with white. White is generally just an  absence of color, rather than a pigment the dog expresses. For a dog to  be black and tan or tricolor, he must be “n/n” for the dominant black  gene (the K locus). This means that the K locus is not expressed,  and the dog will not be black. Also, the dog must have either two copies  of the “at”, or have one copy of at and one copy of a. The dog must be  n/n for both the “ay” and “aw” alleles in order for “at” to be  expressed. A dog that is “at/at” will always pass on a copy of the “at”  allele to any offspring. This does not ensure that the puppies will be  black and tan. The coat color of the offspring also depends on the genes  of the other parent.

If  a dog is “ky/ky”, the dog must be “n/n” for “ay”, “aw”, and “at” for  the dog to express the a/a color. A dog that is solid black with the  recessive K locus must also have the recessive a/a allele in order to  express the black coloration. This is rare because the “a” is recessive.  It is important to make sure you know the dna of both parents. Because a  dog can also be solid black with “kb/kb” or “kb/ky”, To determine if  the dog is “a/a” or expressing with k locus, a dna color test will be  needed. The “a” allele is sometimes referred to as the recessive  black gene. Because this allele is the most recessive of the four, for a  dog to express this phenotype he must have two copies of the “a”  allele. A full recessive black dog will always pass on the “a” allele to  all offspring. The aa can also be present in other colors. 

The only two possible alleles Kbr – Brindle and Ky– Black.

Possible Combinations:

• Ky/Ky (no copies) – no brindle
• Kbr/Ky (1 copy) – brindle and cannot be fawn even if Ay on the A-Locus
• Kbr/Kbr (2 copies) – brindle and cannot be fawn even if Ay on the A-Locus

The K locus has a large impact on coat color depending on the other genes a dog carries on the A locus.  Coat color is controlled by several different genes in dogs. The K locus, also known as the dominant black gene. The  K locus is dependent on the E locus. If the E locus is “e/e” (recessive  yellow/red- cream), the K locus is not expressed. However, if the E  locus is “E/E or E/e”, the K locus is still expressed.

The  dominant black gene consists of three different alleles. The first  allele, which is dominant, is notated as “kb,” or dominant black. The  dominant black allele is actually a mutation that reduces or eliminates  the expression of the agouti gene (A locus). Because this mutation is  dominant, a dog only needs to have one copy of the mutation to affect  the agouti locus. If a dog is “kb/kb” or “kb/n” that means that they  will be solid black in color.

The  second allele is known as the “brindling” allele and is labeled as  “kbr”. “kbr” is a separate mutation that allows the A locus to be  expressed. However, it causes a brindling of that color. The A locus  represents several different colors, such as fawn/sable, tricolor, tan  points, or recessive black. The “kbr” allele is recessive to the  “kb” allele. This means that if a dog is “kb/kbr”, they will still be  black in color. “kbr” is, however, dominant over the third allele, “ky”.

Bella  The Blue Brindle! Brindle is ONLY ay/kbr. Ay/fawn affects the entire  body color, which is why “kbr ay” is brindle. “at” affects only paws,  cheeks, and eyebrows. “Kbr” combined with “at” will produce a trindle.

The  third allele is named as “ky”. This allele allows the agouti gene to be  expressed without brindling. If a dog is “ky/ky”, the A locus then  determines the dog’s coat color. The “ky” allele is recessive to both  “kb” and “kbr”. This means that if the dog is “kb/ky” or “kbr/ky”, the  dog will not express the A locus like a “ky/ky” dog would. For  example, a dog that is “ay/ay” at the A locus could be fawn/sable if the  dog is “ky/ky”. However, if that same dog is “kb/kb”, the A locus color will be muted.

Brindle is when the dog is “striped”. The dog can be almost any color with brindling: lilac, blue, chocolate, pied, Isabella. Brindle  is dominant over everything including fawn/sable. However, a dog can be  Cream/Platinum or cream covering color, including brindle. The only way to know if a Cream/Platinum dog is brindle is to do a color test. Brindle always has at least one copy “ay” fawn. Trindle has one copy kbr and has at/at or at/a at the “a” locus. Trindle, is a shorter way of saying "tan point brindle". Because brindle “KBR” only affects the “a” locus, there are two genes  it can affect. “AY” and “AT”. “Ay” fawn is a full body color while “at” tan points are only on the feet, cheeks, and eyebrows.Trindle dogs always have “at/at” or “at/a”

This is why you see brindling on the feet, cheeks, and eyebrows in trindle dogs.

Some dna of trindle:

at/at ky/kbr

at/at kbr/kbr

at/a ky/kbr

at/a kbr/kbr

Possible Combinations:

• N/N – (no copies) – does not carry Pied
• N/S (1 copy) – carries but is not visual as pied or very little
• S/S (2 copies) – pied

Pied or piebald is a pattern and is when a French bulldog is predominantly white with colored spotting. Blanket  pied or Irish pied happens when the dog is almost solid in color with  white being on the underside of the dog and ONLY 1 copy of pied.  “They”  don’t know what causes this but “they” believe other factors are  involved. Pieds can come in all colors including brindle and merle. Although rare, ticking (spotting) also happens in pied dogs in many breeds, piebald acts as a  “dosage” trait. This means that the amount of white a dog expresses  depends on how many copies of the S allele a dog carries. Dogs like the  French Bulldog who have a single copy of the S locus allele will express  no white spotting pattern. Dogs that have 2 copies “S/S” will exhibit  more white with very little color. Pied French bulldog can come in ANY  color. They can be lilac pied, blue pied, merle pied, brindle pied, ect. Some carriers of Pied may come out  looking like a Pied. This is called Irish pied. Irish pied is not a true  pied due to only one copy but has the spotting of one. Science hasn’t  figured out what causes Irish pied. Most breeders who produce Irish pied  are convinced there's more to it than just carrying one copy.

Possible Combinations:

• N/N (no copies) – no merle.
• M/N (1 copy) – dog is merle.
• M/M (2 copies) – Double merle and should NOT be done! Great risk of hearing and vision deficiencies.

Merle is a coat pattern. The merle gene creates mottled patches of  color in a solid or piebald coat, blue or weird colored eyes, and  affects skin pigment. The merle allele is dominant. Any dog with one copy of the merle gene will be merle, a dog can not carry merle unless they are genetically merle. Merle can also be hidden under other colors or be so minimal it’s not noticed, like cream, known cryptic or phantom merle. DNA testing is always recommended for any dog prior to breeding, however it’s even more important when one of the parents is merle. A merle should NEVER be bred to another merle, as they can be blind and/or deaf and come with numerous health issues... these dogs are known as double merle. Dogs that are “double merle,” a common term used  for dogs that have two copies of the merle “M/M” trait, are  predominantly white and prone to several health issues including blindness and deafness.  If you purchase a puppy from a litter with merles, for breeding purposes, a dna test is required to make sure you  don’t breed to create an accidental double merle. Merle can affect all coat colors, so you can end up with a lilac merle or an isabella merle. Pattern combinations such as brindle merle and pied merle also exist.In  addition to altering coat color, merle can also change eye color and  the coloring of the nose and paw pads. The merle gene modifies the dark  pigment in the eyes, occasionally changing dark eyes to blue, changing  only one eye, or only part of the eye with flecks. Since Merle causes random modifications, both dark-eyed, blue-eyed,  and odd-colored eyes are possible but not guaranteed. Color on paw pads  and nose may be mottled pink and black.

Possible Combinations:

• Em/Em (2 copies of Mask) – masked
• Em/E (1 copy of Mask) – masked
• Em/e (1 copy of Mask, 1 copy of Cream) – the dog will have a mask but carries cream
• E/E – maskless
• E/e (1 copy of cream) – maskless and carries cream
• e/e (2 copies of cream) – visually cream and can cover other colors

The extension gene, controls production of pigment in melanocytes.  Melanocytes are cells that control the coloration of skin or fur. The  dominant form of the gene, “E” allele, allows the dog to produce  eumelanin, which is a black pigment. This can appear either as “E/e” or  “E/E”.

A mutation in the gene causes the pigment-producing cells  to only produce phaeomelanin instead of eumelanin. This turns all the  eumelanin in the coat to phaeomelanin. This form of the gene is  represented as the “e” allele. The e allele is recessive (“e/e”),  meaning that a dog must have two copies of the MC1R mutation to express  the yellow/cream or red coat color. Recessive red can mask other colors.  It can even mask the merle coloration. “e/e” in frenchies is known as  cream. A third allele exists in the extension gene: “em”. “em” is  also dominant. This means a dog can have “em/e” or “em/em” for the “em”  color to express. This causes the dog to have a black mask on their  face, also known as a melanistic mask. This allele acts similarly  to the E allele in that it causes a black-based coat. Because it is  dominant, a dog only needs one copy of the “em” allele to express. In  solid black dogs with one copy of the “em” allele, the mask is hidden.  This is because the mask and the fur color are both black, and the mask  then becomes “invisible.” However, the dog can still pass on the  melanistic mask to future offspring, even if the mask cannot be seen. It  is also hidden in dilute dogs.

Any color and pattern can be covered in cream, but the two with specific names for that are-

Platinum is a Lilac dog “dd coco” covered in cream. The dna is then “dd coco ee”.

Other colors can also be covered in cream.

Blue covered in cream, chocolate, tan/tri points, Isabella.

However, these are not a true Platinums. Platinum is always Lilac covered in cream.

You’ll find that people commonly call all cream French bulldog covering color, platinum, even I make the mistake.

A Champagne dog is a chocolate or testable chocolate covered in cream. “bb ee” or “coco ee”

The D-locus has two alleles the dominant D – Black or recessive d – blue.

Possible Combinations:

• D/D (no copies) – dilute gene is not present, Black
• D/d (1 copy) – dog carries dilute but does not display it, Black
• d/d – (2 copies) – dog displays dilute, Blue

The D locus is the dilute gene. It’s responsible for reducing the  saturation of coat color. Changing the black to a blue giving a grey or silver apperance. When combined  with other alleles it can change the coat color even more, such as co/co  (lilac) and b/b (Isabella) or co/co and b/b (New Shade Isabella). The protein called melanophilin, is responsible for transporting and  fixing melanin-containing cells. A mutation in this gene leads to  improper distribution of these cells, causing a diluted coat color. The  mutation causing color dilution is recessive, and two copies of the  mutated gene (the D allele or the D locus) are needed to produce the  diluted coat color. The  MLPH mutation affects both eumelanin and phaeomelanin pigments. These  pigments control the color of the dog. Black, brown, and yellow/Cream  dogs can all be affected by the D locus. However, the effects of the  dilution are more pronounced in black dogs. A diluted dog becomes known  as a blue dog. A diluted chocolate dog is often referred to as a lilac (“dd coco”) or Isabella(“dd bb”) and a diluted yellow dog/cream is often called champagne. Dogs that express the diluted are “d/d” in combination with any other color coat code. Brindling does express in dilution. Because  the mutations responsible for the dilution are recessive, a dog can  carry one copy and still express a normal coat color. These dogs can  pass on either the full colored genes or the dilution to any offspring.  This means that two dogs that are full colored can produce a diluted  puppy, as long as both parents carry one copy of the dilution.

Possible Combinations:

• B/B (no copies) – no “brown” dilution
• B/b (1 copy) – No “brown” dilution, but a carrier
• b/b (2 copies) – dog is a “brown” dilution

The B locus changes the coloration from the A and K locus to a shade  of brown. This is a recessive gene which needs two copies to be  expressed visually. It's actually a mutation like th d/d dilution genes. Dogs that are b/b and d/d are called Isabella. New  Shade Isabella is when a dog carries d/d, b/b and the cocoa genes.

A dog that is just b/b is known as Rojo. A dog that is b/b co/co is new shade rojo. 

An isabella is a Testable Chocolate “b/b” combined with Blue “d/d”.

To result in “d/d, b/b”.Some people also call this Lilac. However, lilac is ALWAYS dd coco.

Isabella is more of a light Caramel or light bown color whereas lilac is a lighter blue/silver color.

New Shade Isabella results in dna of “d/d, b/b, co/co” is a lighter shade than isabella.

Possible Combinations:

• Co/Co (no copies) – no “brown” dilution
• N/co (1 copy) – No “brown” dilution, but a carrier
• co/co (2 copies) – dog is a “brown” dilution

The Co locus changes the coloration from the A and K locus to a shade of brown. This color is formally known as “non-testable chocolate”. A dog can be just co/co and be a chocolate brown., or a dog that is  both co/co and b/b are called a lilac, and a dog that is d/d b/b co/co is new shade isabella, a lighter shade of isabella. Sometimes people use the term  lilac for just standard blues because they are a light blue. Even though  they may be lighter than another blue, if they don’t carry two copies  of the cocoa gene they are not a lilac, a lilac will ALWAYS be co/co and d/d. Be careful when purchasing a  puppy as a lot of breeders market as lilac when they are not. This is a  recessive gene which needs two copies to be expressed visually.  Differences in coat, skin and eye color between B locus and Coco dogs are subtle but clear. With two copies of cocoa having a slightly darker coat color and lighter eyes than the more common B related brown dogs. b/b co/co is new shade rojo, a lighter shade of the just b/b rojo.

Mammals produce two kinds of pigment: eumelanin (black and/or brown in color) and phaeomelanin (red and/or yellow in color).

Many genes contribute to the type and amount of pigment produced.

Several  breeds of dogs have an extreme dilution phenotype that has been shown  to only affect the red pigment phaeomelanin. This change in the DNA  results in an amino acid difference in the protein where cysteine  replaces the normal arginine at amino acid 51 (p.Arg51Cys).

This mutation is predicted to have damaging effect on protein function.

MFSD12  is believed to function as a lysosomal transmembrane solute transporter  directly affecting the production of phaeomleanin. In dogs, the MFSD12 In variant has only been shown to decrease red/yellow pigment leaving black/brown pigment unaffected.

In  frenchies the intensity gene affects the cream gene “e/e”. If there are  2 copies of intensity in a cream Frenchie “e/e”, their coat will appear  cream to pure white in color.

Possible Combinations:

• l/l (2 copies) – long hair
• l/n (1 copy) – short hair, but carries long hair gene
• n/n or L/L (no copies) – short hair

The L locus (FGF5 gene) is responsible for the coat length. There are at least 5 known alleles L, L2, L3, L4 and L5. It appears that french  bulldogs carry the L1 and L4 genes for long hair. It doesn’t matter which allele they have. If they have two of either allele, they will be fluffy! You can breed a fluffy carrier to another fluffy carrier or to a full/visual fluffy and have a chance at producing fluffy puppies. There is said to not be a difference between the l4 and l1, but some people do swear that l4 is longer and softer, I have seen mixed results from other breeders... some with shorter fur l4 or longer fur l1, but I can say myself that my l4/l4 dog is indeed softer and has longer fur everywhere compared to my other two that are l1/l4. Also, surprisingly, I have to say that fluffy frenchies actually shed less than their short hair counterparts. Ours actually don’t carry any copy for the shedding allele and have a lower propensity for shedding.