07/09/2026
🧬🐾 SHOULD WE REALLY ELIMINATE EVERY 1-COPY CDDY FRENCH BULLDOG FROM BREEDING?
This is a question worth asking.When genetic testing becomes available, it can be tempting to look at a result and say:
“Positive = don’t breed.
But genetics isn’t always that simple.
🦴 WHAT DOES 1 COPY OF CDDY MEAN?
French Bulldogs can carry 0, 1 or 2 copies of the CDDY-associated FGF4 variant.
Having 1 copy does not mean a French Bulldog will develop IVDD.
Likewise, having 0 copies does not guarantee that a dog will never develop spinal disease.
IVDD is a complex condition influenced by genetics, anatomy, structure and other factors.
So should every healthy 1-copy French Bulldog automatically be removed from a breeding program?
Perhaps we need to think more carefully than that.
🧬 WHAT IF WE USE GENETICS STRATEGICALLY?
Imagine we have:
Dog A — 0 copies CDDY
Healthy spine, good structure, good breathing and good temperament.
Dog B — 1 copy CDDY
Also healthy, excellent structure, excellent temperament and valuable genetic diversity.
Instead of automatically removing Dog B from breeding, a breeder could consider whether a carefully planned mating with a 0-copy dog could help maintain genetic diversity while avoiding producing 2-copy puppies from that mating.
That doesn’t mean “1 copy is safe.”
It means the genetic result should be considered as part of the whole dog and the whole breeding program.
⚠️ BUT THERE’S ANOTHER PROBLEM…
What happens if we remove too many dogs from the gene pool?
We already have a relatively limited gene pool in many purebred breeds.
If breeders repeatedly use the same popular sires because they have the desired health-test results, show titles or appearance, we can unintentionally increase relatedness throughout the breed.
And that can create another problem:
LOWER GENETIC DIVERSITY.
A breeding program can become very “health tested” on paper while the population becomes increasingly related.
🧬 DVL2 MAKES THIS EVEN MORE INTERESTING
DVL2 is associated with important Bulldog characteristics, including the screw tail and aspects of skeletal development.
The Bulldog-associated DVL2 variant is essentially fixed in French Bulldogs.
That means we can’t simply say:
Let’s remove DVL2.”
Doing that would mean fundamentally changing the breed.Instead, we need to think about how we breed the dogs we have.
❤️ THE QUESTION WE SHOULD REALLY BE ASKING
Rather than:
Does this dog carry a variant?”
Perhaps the better question is:How can I use the genetic information I have to make the healthiest possible mating while maintaining genetic diversity?”
That means looking at:
🐾 CDDY status
🐾 DVL2 status
🐾 COI and relatedness
🐾 Family history
🐾 Spine and vertebral health
🐾 Movement
🐾 Breathing
🐾 Body proportions
🐾 Temperament
🐾 Longevity
🐾 Overall health
No genetic test should be considered in isolation.
🌱 BREED FOR THE FUTURE
The goal should not be to produce the most extreme French Bulldog.
And it shouldn’t be to chase a collection of “clear” genetic results while ignoring the bigger picture.
The goal should be to produce healthy, functional, long-lived French Bulldogs while protecting the genetic diversity of the breed.
Genetic testing gives us information.
It is how we use that information that determines whether we improve the breed. ❤️🐾
This is a discussion about responsible breeding strategy, not a recommendation to breed any particular dog. Individual breeding decisions should consider veterinary assessment, genetic counselling, health testing and the dog’s complete pedigree and family history.
