Triple-Locus Ultra-Rare
Isabella French Bulldog
The complete guide to the d/d + b/b + co/co combination. How double dilute chocolate creates the rarest Frenchie color, with DNA testing and pricing.
Model Isabella PairingsThree Genes Create Isabella
Isabella is the result of stacking three recessive genes. Each one progressively lightens the pigment until the final champagne-taupe shade is achieved.
D-Locus (d/d)
Dilute lightens all pigment. Black becomes blue, brown becomes lighter. This is the final lightening step that creates the pale Isabella tone.
B-Locus (b/b)
Chocolate changes black pigment to brown. Combined with dilute, this creates the lilac base. Isabella starts here and goes one step further.
Co-Locus (co/co)
Cocoa further lightens the brown pigment produced by the B-locus. Combined with d/d and b/b, this creates the ultra-pale champagne Isabella shade.
The Color Progression to Isabella
Each gene adds another layer of pigment lightening. Understanding the progression helps you identify and breed for Isabella.
Black
D/D, B/B, Co/CoThe starting point. Full black pigment with no dilution, chocolate, or cocoa.
Blue
d/d, B/B, Co/CoAdd dilute. Black pigment is lightened to blue-gray. One recessive gene applied.
Chocolate
D/D, b/b, Co/CoAdd chocolate. Black pigment changes to brown. A different single-gene modification.
Lilac
d/d, co/co, B/BCombine dilute + cocoa. Brown is lightened to silvery-lilac. Two recessive genes.
Isabella
d/d, b/b, co/coAdd chocolate on top of lilac. The brown is further modified to champagne-taupe. Three recessive genes — ultra-rare.
Isabella Frenchie Pricing
Isabella sits at the top of the Frenchie market. Prices reflect the extreme genetic rarity of producing d/d + b/b + co/co.
Pet Quality
$8,000 – $12,000
Isabella with minor conformation flaws. DNA-verified for all three loci and health genes.
Breed Quality
$12,000 – $20,000
Structurally sound, full health clearances, AKC registration, and proven triple-locus genotype.
Fluffy Isabella
$20,000 – $35,000+
Isabella + longhair gene (L/L). The rarest combination in the Frenchie world. Ultra-premium demand.
Model Isabella Pairings
Our DNA Calculator covers D-locus, B-locus, and co-locus simultaneously. Predict Isabella, lilac, chocolate, and blue outcomes with full accuracy.
Open the DNA CalculatorFrequently Asked Questions
What is an Isabella French Bulldog?
An Isabella French Bulldog is one of the rarest and most expensive color variations in the breed. It is produced by stacking three recessive genes: the dilute gene (d/d at the D-locus), the chocolate gene (b/b at the B-locus), and the cocoa gene (co/co at the co-locus). The result is a pale champagne or taupe-colored coat with lightened nose and paw pads — essentially 'double chocolate' with dilution.
How is Isabella different from Lilac?
Lilac is produced by d/d + co/co (dilute + cocoa). Isabella adds a third gene: b/b (chocolate). So Isabella is d/d + b/b + co/co. The chocolate gene further modifies the brown pigment pathway, producing an even paler, more champagne-toned coat than lilac. Isabella is visibly lighter and more muted than lilac, with a distinctive warm taupe shade.
How much does an Isabella French Bulldog cost?
Isabella French Bulldogs are among the most expensive Frenchies in the world. Prices typically range from $10,000 to $20,000. Ultra-rare combinations like Fluffy Isabella (adding L/L) can command $15,000 to $35,000 or more. The high price reflects the extreme genetic rarity — producing co/co requires both parents to carry the recessive cocoa allele, and combining it with d/d and b/b is statistically uncommon.
Can any DNA test detect Isabella?
Isabella is not a single gene — it is a combination of three genes (d/d, b/b, co/co). To identify an Isabella dog, you need a DNA panel that tests all three loci: D-locus (dilute), B-locus (chocolate), and co-locus (cocoa). Not all DNA panels include the co-locus test. Embark, Animal Genetics, and DDC now offer co-locus testing. Always verify which loci are included in your DNA panel before testing.
Why is Isabella called 'double dilute chocolate'?
The term 'double dilute chocolate' refers to the fact that two separate genes lighten the brown pigment. The B-locus turns black to brown (chocolate). The co-locus further lightens that brown to a cocoa shade. Then the D-locus dilutes everything to a pale champagne tone. So the pigment is 'doubly' lightened — first by cocoa, then by dilute — creating the ultra-pale Isabella shade.
Are Isabella Frenchies healthy?
The color genes that produce Isabella (B, D, and co) do not cause health problems. However, because Isabella is so rare and expensive, unethical breeders may prioritize color over health testing. Always demand DM, HUU, JHC, and CMR1 clearances regardless of coat color. An Isabella Frenchie from a health-tested, ethical breeder is just as healthy as any other color.