A Buyer’s Guide to French Bulldog Colour Genetics in NZ
French Bulldog colour genetics can be confusing for buyers, especially when terms such as blue, black, cocoa, rojo, lilac, Isabella, tan point and fluffy are used in different ways by different breeders. This guide is written from the perspective of Le Epitome Kennels, a Waikato-based French Bulldog and Pug breeder, to help buyers understand common French Bulldog colour terms without losing sight of what matters most: health, breathing, temperament, structure, genetic diversity and matching the right puppy to the right home.
Why Colour Genetics Matters
French Bulldog colour is not just about what a puppy looks like. Many colour traits are inherited through genes that may be visible in the coat or carried quietly without showing. This means two dogs that look similar can still carry very different colour possibilities, and two dogs that look different may share important genetic traits behind the scenes.
DNA testing helps remove guesswork. It allows a breeder to understand which colour and coat traits a dog expresses, which traits it may carry, and what combinations may be possible in future puppies. This is especially important in a planned breeding programme where colour, health, genetic diversity, structure, temperament and family suitability all need to be considered together.
For buyers, understanding colour genetics helps set realistic expectations. A puppy’s colour may be part of the appeal, but it should never be the only factor in choosing a French Bulldog. The best breeding decisions look at the whole dog, not just the colour label.
Common French Bulldog Colour Terms
French Bulldog colour names can be confusing because some terms describe what a dog looks like, while others refer to the genetics behind the coat. Buyers may hear words such as blue, cocoa, rojo, lilac, Isabella, tan point, brindle, trindle and fluffy, but those terms are not always used consistently by every breeder.
Blue usually refers to a soft grey-blue coat tone linked to recessive colour genetics affecting the darker pigment in the coat. Black generally refers to a darker coat presentation, but the genetic basis matters, especially where recessive black is involved. Cocoa and rojo are chocolate-toned colour terms often discussed in French Bulldogs, but DNA testing is needed to understand what a dog actually expresses and carries.
Lilac and Isabella are softer, lighter colour terms that can sometimes be confused by buyers. They may appear as pale taupe, grey-beige, silvery fawn, muted brown or warm diluted tones depending on the dog’s wider genetic profile, markings and lighting.
Tan point refers to tan markings that may appear around areas such as the eyebrows, cheeks, chest, legs and under the tail. Trindle refers to a dog where tan point influence and brindle influence are both involved. Fluffy refers to a longer coat type compared with the traditional short-coated French Bulldog, and a dog can carry fluffy without visibly having a fluffy coat.
Colour Does Not Determine Temperament
A French Bulldog’s colour does not determine its temperament, personality or suitability for a particular home. A blue, rojo, lilac, Isabella, black, cocoa, tan point or fluffy French Bulldog still needs to be assessed as an individual.
DNA Testing and Carried Colour Traits
A French Bulldog can carry colour or coat traits without visibly showing them. For example, a dog may carry blue, cocoa, tan point, fluffy coat or other traits while still appearing to be a different colour. This is why appearance alone is not enough in a serious breeding programme.
DNA testing helps identify what a dog expresses and what it may carry. This allows breeders to make more informed decisions about future pairings, understand possible colour outcomes, avoid unnecessary guesswork and plan with greater care.
Coat Colour Genetics Come from the Wider Canid Family
All domestic dogs trace their ancestry back to ancient wolves. The coat-colour systems we see in modern breeds did not begin with French Bulldogs; they are part of a much older canid genetic inheritance that has been shaped over time by mutation, domestication, breed formation and selective breeding.
This is why many of the same colour genes are discussed across very different breeds. Genes involved in black pigment, red/yellow pigment, sable, tan point, brindle, recessive black, blue, brown, cocoa, merle, white spotting and long coat are not “French Bulldog genes” in isolation. They are part of the wider dog genome, expressed in different ways depending on the breed, the individual dog and the combination of loci involved.
French Bulldog colour genetics are best understood as layers built on top of this broader canine inheritance. The breed has its own common colour terms and breeding history, but the underlying biology sits within the wider science of dog coat colour.
Lets Get Started With The Genetics
The Two Primary Pigments Behind Dog Coat Colour
Most dog coat colours are built from two main pigments: eumelanin and phaeomelanin.
Eumelanin is the darker pigment. In its basic form it appears black, but other genes can modify it into colours such as brown, blue, cocoa, lilac or Isabella. When breeders talk about black-based, blue-based, chocolate-toned, cocoa, lilac or Isabella French Bulldogs, they are usually talking about changes to eumelanin.
Phaeomelanin is the red/yellow pigment. It produces the fawn, sable, tan, cream and red spectrum seen in many French Bulldogs. The intensity of phaeomelanin can vary widely, which is why one fawn dog may look pale cream while another may appear much warmer, deeper or redder.
A French Bulldog’s final colour is not created by one gene on its own. It is built in layers. Some genes decide whether the coat can show dark pigment at all. Other genes decide where dark and red/yellow pigment appear on the body. Other genes then modify those pigments into colours such as blue, cocoa, lilac, Isabella, cream or fluffy-coated lines.
How Coat Colour Genes Work Together
Dog coat colour is controlled by a number of different genes. Each gene sits at a particular location in the genome, called a locus. A dog inherits one copy of each locus from each parent, and the combination of those inherited results helps determine the dog’s final coat colour, pattern and coat type.
These loci do not all do the same job. Some decide whether dark pigment can appear in the coat at all. Some affect whether the dog shows fawn, sable, tan point or recessive black. Others modify dark pigment into colours such as blue, brown, cocoa, lilac or Isabella. Other loci affect patterning, including brindle, pied and merle, while coat-length genes can affect whether a dog is short-coated or fluffy.
The important point is that these genes act in layers. Some loci can hide or override the effect of others, while some only modify pigment that is already present. This is why a French Bulldog’s colour cannot always be understood by appearance alone. DNA testing helps identify the genetic pieces behind the visible coat.
The First Gate: E Locus and Whether the Coat Can Show Dark Pigment
The E locus, also known as MC1R or Extension, is one of the first major gates in dog coat colour. It affects whether a dog can produce eumelanin, the dark pigment, in the hair coat.
If a dog is e/e at the E locus, the coat is restricted to phaeomelanin. In practical terms, that means the dog will show a red, yellow, cream or fawn-type coat rather than expressing black, blue, cocoa, lilac or Isabella in the coat hair. Other dark-pigment genes may still be present genetically, but they may not be visible in the coat.
This is why DNA testing matters. A cream or fawn-looking dog may still carry genes for blue, cocoa, tan point, fluffy coat or other traits, even if those traits are not obvious from looking at the dog.
The K Locus: Dominant Black, Brindle and Allowing the A Locus to Show
The K locus affects how eumelanin and phaeomelanin are distributed in the coat by interacting with the E locus and A locus. In simple terms, it helps decide whether the dog’s A-locus pattern can show clearly, whether brindle may appear, or whether darker pigment may override the pattern.
The traditional K-locus terms are:
KB — dominant black
kbr — brindle
ky — allows the A locus to show
A dog with dominant black at the K locus may not visibly show its A-locus pattern in the normal way, because dominant black can override the pattern that would otherwise be seen. This is why a dog may carry A-locus information such as fawn, tan point or recessive black, but the visible coat still depends on what is happening at the K locus and E locus.
The kbr allele is associated with brindle. Brindle adds darker striping through areas of the coat where phaeomelanin would otherwise show. This is why brindle may appear over fawn/sable areas, and why tan-point dogs can sometimes show brindling within the tan points.
The ky result is often described as the “allow” form, because it allows the A-locus pattern to be expressed, provided the E locus also permits dark pigment to appear in the coat.
In practical breeding terms, the K locus is one reason visible colour can be misleading. A dog’s coat may not show every colour or pattern trait it carries, and a simple visual label may not explain what the dog can produce.
The A Locus: Fawn, Sable, Tan Point and Recessive Black
The A locus, also called the Agouti locus, helps control where dark pigment and red/yellow pigment appear on the dog’s body. In practical breeding conversations, this is where terms such as fawn, sable, tan point and recessive black often come from.
The older breeder shorthand commonly uses:
ay — fawn or sable
at — tan point
a — recessive black
In simple terms, ay-type fawn or sable generally sits above tan point and recessive black in the traditional dominance order. This means a dog with ay may show a fawn or sable-type coat rather than visibly showing tan points or recessive black. A dog with at/at or at/a may be able to show tan points if the E locus and K locus allow that pattern to appear. A dog with a/a may show recessive black, again depending on what is happening at the E locus, K locus and other colour genes.
This is one reason French Bulldog colour can be difficult to understand by appearance alone. A dog may visibly look fawn, sable, tan point or black-based, while also carrying other colour traits that are not immediately obvious. DNA testing helps clarify what the dog expresses, what it carries and what may be possible in future litters.
For buyers, the key point is that the A locus helps set the base pattern, but it does not work by itself. The final coat colour still depends on how the A locus interacts with the E locus, K locus and other colour-modifying genes.
Eumelanin Modifiers: Black, Blue, Brown, Cocoa, Lilac and Isabella
Once a dog can show eumelanin, other genes can modify how that dark pigment appears. Eumelanin is black in its basic form, but it can be changed by different loci into other colours. This is where many of the French Bulldog colour terms buyers hear most often begin to make more sense.
The B locus is associated with brown, often called chocolate or liver in many breeds. It changes black eumelanin into brown-toned pigment. This affects dark pigment, not the red/yellow phaeomelanin areas of the coat.
The D locus is associated with blue. In simple terms, it changes black pigment into a softer grey-blue appearance. A black-based dog affected by blue may appear blue or slate-grey, while the exact visual result still depends on the dog’s wider colour profile and pattern.
Rojo and Cocoa-Based Chocolate Tones
Rojo is a breeder colour term commonly used in French Bulldogs for rich chocolate-toned, red-brown or cocoa-influenced coat colour. It is not a separate official locus like the D locus, B locus or cocoa test.
In practical terms, rojo is often discussed alongside cocoa genetics, especially where a dog is co/co. However, the final coat colour can also be affected by the A locus, tan point patterning, dilution, phaeomelanin intensity, brindle, pied and other modifiers.
This means rojo should be treated as a descriptive colour term rather than a single DNA result. A clear breeder should be able to explain the actual genetics behind the label, including whether the dog is cocoa, carries cocoa, carries blue, has tan point genetics, or has other traits affecting the final colour.
Cocoa
Common shorthand:
co/co
Cocoa is a separate brown coat colour recognised in French Bulldogs. It is not the same as traditional B-locus chocolate. Cocoa is inherited recessively, so a dog generally needs co/co to visually express cocoa. Cocoa was previously often referred to as “non-testable chocolate” before a specific test became available.
In French Bulldog breeding conversations, cocoa is often discussed alongside rojo because many rojo-described dogs are cocoa-based or cocoa-influenced. Cocoa is also commonly associated with lighter amber, yellow or gold-toned eyes, although final eye colour and coat appearance can still be influenced by the dog’s wider pigmentation genetics.
When these modifying genes combine, they can create softer or more complex colour terms such as lilac and Isabella. These names are sometimes used inconsistently by breeders and buyers, so the most accurate description depends on both the DNA results and how the coat presents in the actual dog.
The practical point is that these modifiers act on pigment that is already being produced. They do not replace the base-pattern genes; they modify the colour of the pigment within the pattern already set by the E, K and A loci.
Dilution: The D Locus and Blue-Based Colours
Dilution is one of the most important concepts in coloured French Bulldog genetics. It affects eumelanin, the darker pigment in the coat, and can lighten darker colours into softer, paler shades.
The D locus is commonly associated with dilute or blue colouring in dogs. In simple terms, when a dog inherits the relevant dilute genetics from both parents, black pigment may appear as blue, slate grey or silver-grey rather than true black. This is why “blue” French Bulldogs are not bright blue, but a softened grey-blue version of black-based pigment.
Dilution can also affect other eumelanin-based colours. When dilute genetics combine with brown, cocoa or other chocolate-toned pigment, the final coat colour may be described using terms such as lilac, Isabella, new shade Isabella or other softened colour labels, depending on the dog’s full genetic profile and how the colour presents visually.
Dilution does not create the base pattern by itself. A dog still needs the underlying genetics for its base pattern, such as fawn, tan point, recessive black or another A-locus pattern. Dilution modifies the pigment within that pattern rather than replacing the pattern.
For buyers, the practical point is that blue, lilac and Isabella colours are layered colours. They are not caused by one colour gene acting alone. The visible coat depends on the interaction between base pattern, eumelanin modifiers, dilution, phaeomelanin intensity, patterning and sometimes coat length.
Phaeomelanin Modifiers: Fawn, Red, Cream and Intensity
Phaeomelanin is the red/yellow pigment in the coat. In French Bulldogs, this pigment is involved in colours such as fawn, sable, red fawn, cream and tan point markings. The same broad pigment family can produce a wide visual range, from pale cream through to warm gold, deep fawn or stronger red tones.
This is why two dogs may both be described as fawn but look quite different. One may appear pale cream or light beige, while another may have a much warmer red-fawn appearance. These differences are not only about the A locus. Other genetic factors can affect the intensity of phaeomelanin and change how rich, pale, warm or red the coat appears.
Cream and very pale fawn dogs can also hide other colour genetics. A dog may look light cream or fawn while still carrying traits such as blue, cocoa, tan point, fluffy coat or other colour modifiers. Those carried traits may not be obvious from appearance alone, but they can still matter in future breeding plans.
For buyers, the practical point is that fawn, red fawn and cream are not simply “plain” colours. They are part of the phaeomelanin spectrum, and their final appearance depends on how multiple loci interact, including base pattern, pigment intensity and any other colour traits the dog carries.
Coat Length: Fluffy French Bulldogs and the FGF5 Gene
Fluffy French Bulldogs have a longer coat type compared with the traditional short-coated French Bulldog. This is not a separate breed type. It is a coat-length trait controlled by inherited genetics.
The gene most commonly discussed in relation to long coat in dogs is FGF5. FGF5 variants are not unique to French Bulldogs; long coat genetics are found across a range of dog breeds. UC Davis notes that five recessive variants in the FGF5 gene are associated with long-hair phenotypes in dogs. More recent research has also identified additional FGF5 variants linked to long coat, which shows that coat-length genetics can be more varied than older testing models suggested.
A French Bulldog can carry a long-coat or fluffy variant without visibly having a long coat. These dogs are often called fluffy carriers. A visually fluffy puppy generally needs to inherit relevant long-coat genetics from both parents.
A longer coat may give a dog more coat coverage and some additional insulation compared with a very short coat, but it does not change the basic care needs of the breed. French Bulldogs are still companion dogs and brachycephalic dogs. They still need sensible temperature management, safe indoor living, heat awareness, and protection from cold, wet or extreme conditions.
For buyers, the important distinction is between a fluffy carrier and a visually fluffy French Bulldog. A carrier may look like a standard short-coated French Bulldog but carry the coat-length trait. A visually fluffy French Bulldog has inherited the longer coat type and shows it in the coat.
Patterning Genes: Brindle, Trindle, Pied and Merle
Once the base colour and pigment modifiers are understood, the next layer is patterning. Patterning affects where colours appear on the dog, how they are broken up, and whether extra markings such as brindle striping or white spotting are present.
Brindle is associated with the K locus. It creates darker striping through areas where red/yellow pigment would otherwise show. In French Bulldogs, this can appear as obvious dark striping or as a more subtle overlay depending on the dog’s base colour and other modifiers.
Trindle is a breeder term usually used for a dog that has both tan point influence and brindle influence. In practical terms, the dog may show tan point areas with brindle striping through those points. This is a useful descriptive term, but it should still be understood alongside DNA results and the dog’s actual coat.
Pied refers to white spotting. In French Bulldogs, pied dogs have areas of white combined with coloured patches. The S locus and MITF region are commonly discussed in relation to piebald or white spotting, although white patterning is not always perfectly predictable from one simple result.
Merle is a separate pattern that creates irregular patches of diluted pigment and solid colour. Merle is visually striking, but it should be handled carefully in breeding discussions because merle-to-merle pairings can create serious welfare risks. Buyers should be cautious of any breeder treating merle as purely cosmetic without discussing genetics, pairing choices and health implications.
The practical point is that patterning sits on top of the base colour and pigment modifiers. A dog may be blue brindle, rojo trindle, lilac pied, Isabella and tan, or another combination because several colour and pattern systems are interacting at the same time.
What “New Shade” Means in French Bulldogs
“New shade” is not a single gene or one fixed genetic result. It is a breeder term used to describe certain refined colour palettes that sit outside older, simpler colour descriptions. In French Bulldogs, it is often used where several colour traits combine to create softer, warmer, paler or more unusual coat tones.
This is why terms such as new shade Isabella, new shade rojo or new shade lilac can be confusing for buyers. The phrase may describe the way the dog looks, but it does not replace DNA testing or a proper understanding of the dog’s colour genetics.
A new shade French Bulldog may involve combinations of colour traits such as cocoa, blue, brown/chocolate, tan point, intensity, cream, fawn, Isabella or other modifiers, depending on the dog’s actual genetic profile. Different breeders may also use the phrase slightly differently, which is why it should be treated as a descriptive colour term rather than a precise scientific category.
For buyers, the practical point is this: if a dog is described as new shade, ask what the DNA results actually show. A clear breeder should be able to explain the relevant colour traits, what the dog expresses, what the dog carries, and why the colour description is being used.
For Those That Want To Do A Deeper Dive: Agouti, ASIP and the A Locus
The A locus is also known as the Agouti locus, and the main gene involved is ASIP, or Agouti Signalling Protein. ASIP helps control the switching between eumelanin, the dark pigment, and phaeomelanin, the red/yellow pigment. This affects where dark and red/yellow pigment appear on the dog’s body.
In older breeder terminology, the A locus was often described using a simple dominance order:
ay > aw > at > a
In that model, ay is commonly associated with fawn or sable, aw with wolf sable or agouti, at with tan point, and a with recessive black. This older model is still useful for understanding many breeding conversations, because many colour discussions still use terms such as ay/a, at/a and a/a.
However, the newer understanding of ASIP is more complex than the old four-allele model. Modern research has shown that some coat patterns are influenced by ASIP promoter variants and combinations rather than only one simple allele sitting above another. This helps explain why some dogs do not fit neatly into the older ay, aw, at and a categories.
For buyers, the practical point is simple: A locus results help explain base colour and pattern, but they do not tell the whole story on their own. The E locus, K locus, B locus, cocoa, dilute/blue, intensity, pied, merle, brindle and coat-length genes may all affect what the dog actually looks like.
Putting the Layers Together: How Final Coat Colour Is Built
A French Bulldog’s final coat colour is built from several genetic layers working together. One layer may decide whether dark pigment can appear in the coat. Another may affect whether the dog is fawn, sable, tan point or recessive black. Other genes may then modify dark pigment into blue, brown, cocoa, lilac or Isabella, while separate genes may affect red/yellow intensity, coat length or patterning.
This is why a full colour description can sound complicated. A dog may be described as blue and tan, rojo trindle, lilac fawn, Isabella and tan, new shade Isabella, or a fluffy carrier. Those descriptions are built from more than one genetic system interacting at the same time.
For example, a blue and tan French Bulldog is not simply “blue”. The dog must have a base pattern that allows tan points to show, while also having the colour genetics that modify the darker pigment into a blue appearance that may vary in shade and include other pigments layered within it. A fluffy carrier may look short-coated but still carry coat-length genetics that could matter in future breeding plans. A cream or fawn dog may look simple on the surface but still carry hidden colour traits that are not visible in the coat.
This is why serious colour planning should use DNA testing, visual assessment and breeding records together. The DNA result helps explain the genetic pieces. The dog itself shows how those pieces present in real life.
Common French Bulldog Colours:
Practical Genotype Shorthand
The following section uses common breeder shorthand to explain the genetics often associated with French Bulldog colours. This is not a complete scientific interpretation of every possible result. Modern DNA testing, especially around the A locus / ASIP, is more detailed than older shorthand such as ay, at and a. However, these terms are still widely used in breeding conversations and are useful for understanding how many colour labels are built.
As a general rule, colour should be read in layers:
E locus — whether dark pigment can appear in the coat
K locus — whether brindle or dominant black affects the pattern
A locus — whether the dog is fawn/sable, tan point or recessive black
D locus — whether dark pigment is diluted to blue
B locus and cocoa — whether dark pigment is modified into brown, chocolate or cocoa tones
Other modifiers — intensity, pied, merle, fluffy and other traits
Fawn / Sable
Common shorthand:
ay/ay, ay/at or ay/a at the A locus
Fawn and sable are commonly associated with ay-type A-locus results in older breeder terminology. These dogs are on the red/yellow phaeomelanin side of coat colour, although the final shade can vary from pale fawn through to warm gold, deep fawn or red-fawn depending on intensity and other modifiers.
A dog may also carry tan point, recessive black, blue, cocoa, fluffy or other traits without those traits being obvious in the visible coat.
Cream
Common shorthand:
e/e at the E locus, with intensity modifiers affecting shade
Cream is usually discussed through the E locus because an e/e dog is restricted to phaeomelanin in the hair coat. The final shade may vary from warmer cream through to very pale cream or near-white depending on phaeomelanin intensity and other modifiers.
A cream dog can still carry hidden traits such as blue, cocoa, tan point, recessive black, pied, merle or fluffy. Those traits may not be obvious from appearance alone.
Tan Point
Common shorthand:
at/at or at/a at the A locus
Tan point dogs have darker pigment across much of the body, with tan markings usually appearing around areas such as the eyebrows, cheeks, chest, legs and under the tail. For tan points to show clearly, the wider E locus and K locus profile must allow the A-locus pattern to be expressed.
Tan point can combine with other traits. For example, a dog may be blue and tan, chocolate and tan, rojo and tan, lilac and tan, Isabella and tan, or fluffy and tan depending on the rest of the genetic profile.
Recessive Black
Common shorthand:
a/a at the A locus
Recessive black is commonly described as a/a. This can produce a dark, eumelanin-based coat when the E locus allows dark pigment to appear and the K locus does not prevent the pattern from being expressed.
Other genes may then modify that black pigment. For example:
a/a + d/d may produce a blue-type dog
a/a + co/co may produce a cocoa or rojo-type dog
a/a + b/b may produce a traditional chocolate/brown-type dog
a/a + d/d plus brown or cocoa modifiers may produce softened colours such as lilac, Isabella or related breeder descriptions, depending on the terminology being used
Blue
Common shorthand:
d/d at the D locus, with dark pigment present
Blue is caused by dilution acting on eumelanin, the darker pigment. A blue French Bulldog is not “blue” because of the A locus alone. The dog needs dilute genetics at the D locus, while the A locus and K locus help determine the pattern in which the blue appears.
For example:
a/a + d/d may produce a solid or mostly solid blue-type dog
at/a + d/d or at/at + d/d may produce a blue and tan dog
ay/a + d/d or ay/at + d/d may contribute to blue fawn or related expressions, depending on the wider colour profile
Blue and Tan
Common shorthand:
at/at or at/a at the A locus, plus d/d at the D locus
Blue and tan combines tan point patterning with dilution. The A locus provides the tan point pattern, while the D locus modifies the darker pigment into a blue, slate-grey or silver-grey appearance.
The tan markings themselves are phaeomelanin-based, so they may appear cream, tan, gold or warmer depending on intensity and other modifiers.
Blue Fawn
Common shorthand:
ay-based fawn/sable influence, plus d/d at the D locus
Blue fawn is usually used where a fawn or sable-based dog also has dilution affecting the darker pigment areas, such as the mask, shading, nose pigment or other eumelanin areas. The dog is not blue in the same way as a solid blue dog. Instead, the fawn coat remains on the phaeomelanin side, while the darker pigment is softened by dilution.
The exact appearance can vary significantly depending on E locus, K locus, A locus, mask, intensity, brindle and other modifiers.
Cocoa
Common shorthand:
co/co
Cocoa is a separate brown coat colour recognised in French Bulldogs. It is not the same as traditional B-locus chocolate. Cocoa is associated with the HPS3 gene and was previously often referred to as non-testable chocolate before a specific test became available.
Cocoa is inherited recessively, so a dog generally needs co/co to visually express cocoa. In older French Bulldog colour discussions, this is often what people meant when they referred to the original non-testable chocolate colour in the breed.
Cocoa is also commonly associated in French Bulldog breeding conversations with lighter amber, yellow or gold-toned eyes, although final eye colour and coat appearance can still be influenced by the dog’s wider pigmentation genetics.
Chocolate / Brown / Testable Chocolate / Rojo
Common shorthand:
b/b at the B locus, where the relevant brown variants are present
Traditional brown, chocolate or liver is associated with the B locus, also known as TYRP1. In general dog genetics, the B locus modifies black eumelanin into brown or chocolate pigment. It does not directly change red/yellow phaeomelanin.
In French Bulldog breeder terminology, b/b is often called testable chocolate because it can be identified through DNA testing at the B locus. Many French Bulldog breeders also use the term rojo for this testable chocolate colour, especially where the coat presents as a rich red-brown or chocolate tone.
A dog may be chocolate, chocolate and tan, chocolate fawn, chocolate brindle or chocolate pied depending on the other loci involved.
Rojo
Common shorthand:
b/b is commonly referred to as testable chocolate or rojo in French Bulldog breeder terminology
Rojo is a breeder colour term rather than a separate official testable locus. In many French Bulldog breeding circles, rojo is used for b/b testable chocolate dogs, especially where the dog has a rich red-brown, chocolate or warm cocoa-like appearance.
The final appearance of a rojo dog still depends on the full genetic picture. The A locus may affect whether the dog is recessive black, tan point or fawn/sable based. The D locus may soften the coat if dilution is present. Cocoa, intensity, brindle, pied and tan point can also change how the colour presents.
Common examples:
a/a + b/b may produce a solid or mostly solid testable chocolate / rojo-type dog, depending on the wider profile
at/a + b/b or at/at + b/b may produce rojo and tan, if the tan point pattern is allowed to show
ay/a + b/b or ay/at + b/b may contribute to rojo fawn or chocolate-influenced fawn expressions, depending on the wider profile
b/b + co/co is often described by breeders as new shade rojo
b/b + d/d may be described as Isabella in traditional chocolate/dilute terminology, depending on the dog’s full DNA and visual coat
Because rojo is breeder terminology, the safest approach is to ask what the DNA actually shows rather than relying on the colour label alone.
Lilac
Common shorthand:
d/d plus chocolate-type pigment, with breeder terminology varying
Lilac generally refers to a softened chocolate-toned colour where dilution is also present. In breeder usage, lilac may refer to different chocolate pathways depending on the line and the terminology being used.
Common examples may include:
b/b + d/d in traditional testable chocolate / dilute terminology
co/co + d/d in cocoa-based French Bulldog colour terminology
b/b + co/co + d/d in some new shade or highly modified colour descriptions
Because French Bulldog colour terminology varies, lilac should be understood as a layered colour description rather than one simple locus.
Isabella
Common shorthand:
b/b + d/d in traditional testable chocolate / dilute terminology
Isabella is commonly used for a pale diluted brown or chocolate-toned coat. In traditional genotype shorthand, Isabella is often described as b/b plus d/d, meaning testable chocolate combined with dilution.
In French Bulldogs, Isabella may appear as pale taupe, muted beige, silvery fawn, warm diluted brown or a soft grey-brown tone depending on the dog’s full genetic profile. Cocoa, tan point, cream, intensity, pied, brindle and other modifiers may also influence how the coat presents.
Because Isabella terminology can vary between breeders, the safest approach is to look at both the DNA results and the actual dog.
New Shade Isabella / New Shade Rojo
Common shorthand:
A descriptive breeder term involving multiple colour modifiers
New shade is not a single genotype. It is a descriptive term used where several colour traits combine to create a refined, pale, warm, unusual or highly modified coat tone.
In many French Bulldog breeding conversations:
b/b may be described as testable chocolate or rojo
co/co may be described as cocoa or old non-testable chocolate
b/b + co/co may be described as new shade rojo
b/b + d/d may be described as Isabella
b/b + co/co + d/d may be described as new shade Isabella, depending on breeder terminology and visual coat presentation
A breeder using “new shade” should be able to explain the actual DNA behind the dog, not just rely on the colour label.
Brindle
Common shorthand:
kbr at the K locus
Brindle is associated with the K locus and creates dark striping through areas where red/yellow pigment would otherwise appear. Brindle can appear over fawn/sable areas and may also appear within tan point markings.
Trindle
Common shorthand:
Tan point genetics plus brindle influence
Trindle usually means the dog has both tan point influence and brindle influence. In practical terms, the dog may show tan markings with brindle striping through those tan areas.
Common shorthand may involve:
at/at or at/a at the A locus
plus kbr at the K locus
with the E locus and wider profile allowing the pattern to show
Pied
Common shorthand:
S locus / white spotting influence
Pied is a white spotting pattern. It can cover or hide parts of the dog’s underlying colour, which is why a pied dog’s visible patches may not show every colour trait the dog carries.
For example, a pied dog may genetically carry blue, cocoa, tan point, brindle or fluffy traits even if much of the visible coat is white.
Merle
Common shorthand:
Merle pattern influence at the merle locus
Merle is a pattern, not a base colour. It creates irregular patches of diluted and solid colour. Merle should be handled carefully in breeding discussions because merle-to-merle pairings can create serious welfare risks.
A merle dog may also be blue merle, chocolate merle, lilac merle, Isabella merle, merle and tan, or another layered description depending on the rest of the dog’s colour genetics.
Fluffy
Common shorthand:
Long coat / fluffy genetics, commonly associated with FGF5
Fluffy is not a colour. It is a coat-length trait. A dog can be a fluffy carrier without looking fluffy, and a visually fluffy puppy generally needs to inherit relevant long-coat genetics from both parents.
Fluffy can combine with any colour or pattern. For example, a French Bulldog may be fluffy rojo, fluffy Isabella, fluffy blue and tan, fluffy lilac, fluffy fawn or a fluffy carrier with no visible long coat.
Why DNA Testing Does Not Replace Assessing the Dog
DNA testing is extremely useful, but it does not replace assessing the actual dog. A DNA result can explain what colour traits a dog expresses or carries, but it does not tell the full story of the dog’s structure, movement, breathing, temperament, fertility, whelping history, family history or long-term health.
This is especially important in breeds such as French Bulldogs, where responsible breeding decisions should consider far more than coat colour. A dog may have an interesting or valuable colour profile but still be unsuitable for breeding if it does not meet the wider standard of health, temperament, structure and suitability.
Visual assessment also matters because DNA results do not always predict exactly how a colour will present in real life. Coat tone, shading, markings, expression, head type, balance and overall quality are still assessed by looking at the dog itself, not only the test report.
For buyers, DNA testing is a useful sign that a breeder is taking colour and inherited traits seriously. However, it should sit alongside good husbandry, careful selection, veterinary input, long-term knowledge of the lines and honest assessment of each dog as a whole.
References and Further Reading
UC Davis Veterinary Genetics Laboratory — Dog Coat Color and Type
https://vgl.ucdavis.edu/resources/dog-coat-color
Supports: general dog coat colour overview, eumelanin, phaeomelanin, E locus, K locus, A locus and how coat-colour genes interact.
UC Davis Veterinary Genetics Laboratory — Dog Coat Color: French Bulldog Panel
https://vgl.ucdavis.edu/panel/dog-coat-color-french-bulldog
Supports: French Bulldog-specific coat-colour testing, including Agouti, Brown/Chocolate/Liver, Cocoa, Dilute/Blue, Dominant Black, Merle, long coat/fluffy and other relevant loci.
UC Davis Veterinary Genetics Laboratory — Dog Coat Color: Basic Panel
https://vgl.ucdavis.edu/panel/dog-coat-color-basic-panel
Supports: general coat-colour testing terminology across breeds, including MC1R/E locus, Brown/B locus, D locus, K locus and other basic coat-colour concepts.
UC Davis Veterinary Genetics Laboratory — Agouti / A Locus
https://vgl.ucdavis.edu/test/agouti-dog
Supports: Agouti/ASIP, A locus terminology, fawn/sable, tan point, recessive black, and interaction with other coat-colour loci.
UC Davis Veterinary Genetics Laboratory — Dominant Black / K Locus
https://vgl.ucdavis.edu/test/dominant-black
Supports: K locus, dominant black, brindle, fawn expression and interaction with MC1R/E locus and Agouti/A locus.
UC Davis Veterinary Genetics Laboratory — Brown / B Locus / Chocolate / Liver
https://vgl.ucdavis.edu/test/brown-dog
Supports: B locus brown/chocolate/liver, and how brown modifies black eumelanin without affecting red/yellow phaeomelanin.
UC Davis Veterinary Genetics Laboratory — Cocoa
https://vgl.ucdavis.edu/test/cocoa-dog
Supports: cocoa in French Bulldogs, cocoa as a brown coat colour, previous “non-testable chocolate” terminology, and autosomal recessive inheritance.
UC Davis Veterinary Genetics Laboratory — Dilute / D Locus / Blue
https://vgl.ucdavis.edu/test/dilute-dog
Supports: dilute/blue coat colour, D locus terminology, and how dilute variants affect coat colour.
UC Davis Veterinary Genetics Laboratory — Intensity Dilution
https://vgl.ucdavis.edu/test/intensity-dog
Supports: phaeomelanin intensity, cream-to-white dilution of red/yellow pigment, and why fawn/red/cream shades can vary.
UC Davis Veterinary Genetics Laboratory — Coat Length / Long Hair
https://vgl.ucdavis.edu/test/coat-length-dog
Supports: FGF5, long coat/fluffy, five recessive long-hair variants, fluffy carriers, inheritance and relevance across dog breeds.
UC Davis Veterinary Genetics Laboratory — Merle
https://vgl.ucdavis.edu/test/merle
Supports: merle as an incompletely dominant coat-colour pattern with irregular patches of diluted and solid colour.
UC Davis Veterinary Genetics Laboratory — Piebald / White Spotting / S Locus
https://vgl.ucdavis.edu/test/piebald
Supports: pied/piebald/white spotting, S locus terminology, MITF region and variable white pattern expression.
Kiener et al. — Novel Brown Coat Color (Cocoa) in French Bulldogs Results from a Nonsense Variant in HPS3
https://pmc.ncbi.nlm.nih.gov/articles/PMC7349258/
Supports: cocoa as a distinct brown coat colour in French Bulldogs associated with HPS3, separate from traditional TYRP1/B-locus brown.
Bannasch et al. — Dog Colour Patterns Explained by Modular Promoters of Ancient Canid Origin
https://www.nature.com/articles/s41559-021-01524-x
Supports: modern ASIP/Agouti understanding, modular promoter model, and why the older simple ay > aw > at > a model is incomplete.
Bannasch et al. — Dog Colour Patterns Explained by Modular Promoters of Ancient Canid Origin, PubMed record
https://pubmed.ncbi.nlm.nih.gov/34385618/
Supports: citation record for the ASIP modular promoter paper.
Everts et al. — Discovery of Four New FGF5 Variants Causing Long Hair in the Dog
https://pmc.ncbi.nlm.nih.gov/articles/PMC12983947/
Supports: newer research showing additional FGF5 variants can be associated with long hair, beyond older known testing models.