CDDY in Doodles: What Every Owner Should Know
If you’ve been researching Bernedoodles, Goldendoodles, Cavapoos, or other Doodles and have come across the terms CDDY, IVDD, or CDPA on a genetic health test, the results can sound alarming at first.
The reality is more nuanced.
CDDY is an important genetic variant that responsible breeders should understand, test for, and consider when making breeding decisions. But a positive CDDY result is not the same thing as a diagnosis of IVDD, nor does it mean that a dog will inevitably develop a back problem.
This distinction is especially important in Doodles because CDDY is extremely common in some of the breeds used to create them — particularly Miniature and Toy Poodles and Cavalier King Charles Spaniels.
What Is CDDY?
CDDY stands for Chondrodystrophy.
It is associated with an extra copy of the FGF4 gene on canine chromosome 12. This genetic variant affects both skeletal development and the intervertebral discs — the cushioning discs located between the vertebrae of the spine.
Dogs with one or two copies of CDDY experience changes in their intervertebral discs earlier in life than dogs without the variant. Those changes can make the discs more susceptible to degeneration and, in some dogs, eventual herniation.
That is why genetic testing companies often label the result something similar to:
CDDY / IVDD Risk
The important word is risk.
CDDY increases susceptibility to Hansen Type I intervertebral disc disease, but carrying the variant does not mean that a dog will necessarily experience a clinically significant disc herniation. UC Davis specifically notes that multiple factors appear to influence whether an individual dog ever experiences a herniated disc.
CDDY Is Common in Miniature Poodles
This is one of the most important pieces of context when discussing CDDY in Doodles.
CDDY is not an unusual mutation occasionally appearing in poorly bred Poodles. It is deeply established within the Miniature and Toy Poodle population.
Data published by the UC Davis Veterinary Genetics Laboratory reported a CDDY allele frequency of approximately 57% in Miniature and Toy Poodles in the population studied.
By comparison, the same dataset found the variant essentially fixed in several other breeds, including Cavalier King Charles Spaniels and Beagles.
That means eliminating every CDDY-carrying Miniature Poodle from breeding overnight would remove a very substantial portion of the available genetic population.
And that can create an entirely different set of problems.
Responsible breeding is not simply about eliminating every detectable genetic variant. Breeders must consider the entire dog: genetic diversity, orthopedic health, cardiac health, temperament, structure, longevity, fertility, immune health, and dozens of other traits.
UC Davis addresses this issue directly. For breeds where CDDY occurs at a high frequency, they recommend reducing it slowly across multiple generations rather than eliminating large portions of the breeding population at once.
That philosophy closely mirrors our approach.
A Genetic Risk Variant Is Not the Same as Clinical Disease
This may be the most misunderstood part of CDDY testing.
A genetic test tells us that a dog carries a variant associated with increased susceptibility.
It does not tell us that the dog currently has a herniated disc, will develop symptoms, will require surgery, or will ever experience a spinal problem during its lifetime.
Researchers have demonstrated that the CDDY variant alters intervertebral disc biology and increases the risk of disc herniation. At the same time, they also recognize that not every genetically predisposed dog develops clinical disease.
This helps explain something we have observed within our own program.
Miniature Poodle genetics have been part of our lines for many years, and CDDY has therefore been present within portions of our breeding population. Despite producing thousands of dogs over more than a decade, we have not observed a corresponding pattern of widespread spinal disease in our lines.
That does not mean CDDY has no significance.
It means genetic results have to be interpreted alongside the real-world phenotype and health history of the dogs and their relatives rather than interpreted in isolation.
Why Dachshunds Are Different
When families hear “IVDD,” they often immediately think of Dachshunds.
There is a reason for that.
Certain breeds combine genetic susceptibility to disc degeneration with an extremely distinctive body structure — very short limbs relative to a long torso.
Research into IVDD has consistently identified Dachshunds among the breeds with particularly high clinical rates of disc disease. One large insurance-based study of more than 665,000 dogs found Miniature Dachshunds had the highest incidence of intervertebral-disc-degeneration-related disease among the breeds evaluated.
Structure matters as well.
Research has demonstrated that body proportions can influence spinal biomechanics and IVDD risk, particularly in dogs with extreme long-and-low conformation.
That is one reason we pay very close attention not only to genetic tests, but also to physical structure.
A structurally balanced Poodle or Doodle carrying CDDY is not physically identical to an extremely short-legged, long-backed Dachshund, even though both may carry an FGF4-related genetic variant.
Genetics are part of the picture. Structure is another part.
CDDY vs. CDPA: They Are Not the Same Thing
This is another area where genetic reports can create confusion.
There are actually two separate FGF4 retrogene variants commonly discussed in connection with canine leg length.
CDDY — Chromosome 12
CDDY is caused by an FGF4 retrogene insertion on chromosome 12.
It can influence leg length, but its major health significance is that it causes premature degeneration of the intervertebral discs and increases susceptibility to Hansen Type I IVDD.
CDPA — Chromosome 18
CDPA, or Chondrodysplasia, results from a different FGF4 retrogene located on chromosome 18.
CDPA is strongly associated with the pronounced short-legged phenotype seen in breeds such as Dachshunds, Basset Hounds, Corgis, West Highland White Terriers, and Scottish Terriers.
When a dog carries both FGF4 variants, UC Davis reports that the reduction in leg length can be more pronounced.
This distinction is extremely important in our breeding program.
Why We Do Not Breed CDPA-Carrying Dogs
Our goal has always been to produce dogs with sound, functional structure.
We do not breed from dogs carrying CDPA.
When CDPA began appearing within portions of the broader Doodle breeding world, the resulting dogs could have a noticeably exaggerated short-legged, elongated appearance — sometimes informally described as a “low rider” or “weiner-doodle” structure.
That is not the structure we want to produce.
We want our dogs standing on balanced, appropriately proportioned legs with an athletic and functional build.
Genetic testing allows us to identify CDPA rather than relying solely on appearance, and keeping CDPA out of our program has been an established part of our breeding approach.
It is also important to be scientifically precise: CDPA itself is primarily a structural FGF4 variant, whereas CDDY is the FGF4 variant directly associated with premature intervertebral disc degeneration.
A large study evaluating both variants found that the chromosome-12 CDDY variant — rather than the chromosome-18 FGF4 variant — was strongly associated with disc herniation.
How to Read a Genetic Test
This distinction becomes easier to understand when looking at an actual genetic report.
For example, a dog might receive:
CDDY/IVDD: N/CDDY — one copy of the risk variant
and separately:
CDPA: N/N — clear
Those results tell us two different things.
The dog carries one copy of the chromosome-12 CDDY variant, meaning it has a genetic predisposition to premature intervertebral disc degeneration.
At the same time, the dog is clear of the chromosome-18 CDPA variant associated with the pronounced short-limbed phenotype.
That is very different from saying, “This dog has IVDD.”
It doesn’t.
The result identifies genetic susceptibility.
Why We Don’t Simply Remove Every CDDY Dog From Breeding
At first glance, the obvious solution might seem to be:
Why not breed only CDDY-clear dogs?
If we were dealing with a rare genetic mutation in a breed with plenty of clear dogs available, that could be a reasonable strategy.
But population genetics becomes much more complicated when a variant is present in the majority of a breed’s genetic population.
UC Davis specifically recommends that breeds with high CDDY frequency reduce the variant gradually over multiple generations so genetic diversity is not unnecessarily sacrificed.
Removing a huge percentage of otherwise exceptional Miniature Poodles from the breeding population could inadvertently concentrate completely different genetic problems.
We therefore look at the whole dog and the whole pedigree.
That includes:
CDDY status
CDPA status
orthopedic testing
cardiac health
additional genetic disease screening
physical structure
temperament
health and longevity within the pedigree
reproductive health
genetic diversity
the health history of offspring already produced
No single genetic marker should replace comprehensive breeding judgment.
Our Approach to CDDY Moving Forward
We take CDDY seriously.
We also take genetic diversity seriously.
Our goal is to responsibly reduce CDDY within our breeding population over time, particularly when we can make pairings that reduce the likelihood of passing the variant forward without sacrificing other important qualities.
This will be a gradual, generational process.
That approach is consistent with UC Davis guidance for breeds in which CDDY occurs at high frequency.
At the same time, we do not breed dogs carrying CDPA because we do not want to introduce the exaggerated short-legged structural phenotype associated with that variant.
This allows us to work toward reducing CDDY while maintaining the balanced structure, temperament, genetic diversity, and overall health that are equally important to our program.
What About Our Smallest Doodles and Munchkins?
There is another genetic reality worth discussing openly.
Our smallest dogs sometimes incorporate breeds in which CDDY is extraordinarily common.
For example, the Cavalier King Charles Spaniel population evaluated by UC Davis had a CDDY allele frequency of 1.00 — essentially fixed in that population.
Cavalier genetics contribute valuable traits, particularly temperament, size, and appearance, to certain lines.
Completely eliminating CDDY while continuing to incorporate Cavalier genetics may therefore be unrealistic.
That doesn’t mean we ignore CDDY.
It means breeding decisions have to balance multiple genetic priorities rather than focusing on one test result at the expense of everything else.
What Should Owners Do?
For the overwhelming majority of families, a CDDY result should be viewed as useful health information rather than a prediction that their dog will develop IVDD.
Maintaining a healthy weight and good muscle condition is beneficial for overall orthopedic and spinal health. Owners should also contact their veterinarian if a dog develops symptoms such as unexplained neck or back pain, reluctance to jump or climb stairs, an abnormal gait, weakness, loss of coordination, or sudden mobility changes.
Most importantly, don’t interpret a DNA result without context.
CDDY positive does not mean “my dog has IVDD.”
It means your dog carries a genetic variant associated with increased susceptibility to disc degeneration and herniation.
Those are very different statements.
The Bottom Line
CDDY is real, and responsible breeders should know about it.
But responsible genetics also requires context.
CDDY is highly prevalent in Miniature and Toy Poodles and essentially fixed in some other breeds used in smaller companion-dog breeding. Eliminating every carrier immediately could dramatically restrict genetic diversity, which is why veterinary geneticists recommend a gradual breeding strategy in populations where the variant is common.
A CDDY result identifies risk — not destiny.
We have not seen CDDY translate into a pattern of widespread spinal disease within the thousands of dogs produced from our lines, but we continue to monitor our dogs, study emerging research, and use increasingly sophisticated genetic testing to make informed breeding decisions.
At Rocky Road Doodles, our approach is straightforward:
Test extensively. Avoid exaggerated structural traits. Do not breed CDPA carriers. Reduce CDDY thoughtfully over time. Protect genetic diversity. And evaluate the whole dog rather than making breeding decisions based on a single genetic marker.
Canine genetics is continually evolving, and responsible breeding means evolving with it.
As always, we believe families deserve transparency about the genetics behind their puppy — including what a test result means, what it does not mean, and how we use that information to make responsible decisions for future generations.