A Note on Embark’s CDDY/IVDD Testing

For our pet home families reading your pup’s embark result and there is 1 copy of CDDY/IVDD, here is a further explanation and a note on Embark’s CDDY/IVDD Testing.

In the fall of 2020, Embark’s DNA health testing added new DNA marker, CDDY, to its genetic disease panel and CDDY can be associated with IVDD. This particular result is a little nuanced and need further research and explaining. For some background, UC Davis discovered the CDDY mutation gene in 2017, and determined breed related associations in 2019, and as mentioned above, Embark put this into its testing and results in the fall of 2020. At the time, the vast majority of mini poodles showed up with the variant through Embark and it’s classified as ‘at risk’ with one or two alleles on the Embark panel, which makes it look scary. As breeders, at first when this happened, we all had a major freak out session, but then we started doing our research and have a better understanding, we feel much better about this. Here is what we can share.

First, here is what you will get emailed if your embark comes back with 1 or 2 CDDY alleles:

My name is Dr. Kari Cueva, and I am a Veterinary Geneticist on the Embark team. As a clinical veterinarian, I understand how important our genetic health testing is to the well being of *Puppy*. I know that you have been awaiting *Puppy*’s health results, and I can assure you that they are about to be finalized.

I am reaching out to you today to let you know that while *Puppy* does not have risk from most of the genetic variants that we test for, she does have genetic variants associated with the following health condition: Chondrodystrophy and Intervertebral Disc Disease, CDDY/IVDD, Type I IVDD. Please keep in mind while reading these results that this is not a medical diagnosis.

Chondrodystrophy and Intervertebral Disc Disease, CDDY/IVDD, Type I IVDD

*Puppy* has 1 copy of a risk variant associated with this condition.

How to interpret this result

*Puppy* has one copy of an FGF4 retrogene on chromosome 12. In some breeds such as Beagles, Cocker Spaniels, and Dachshunds (among others, [Mini Poodles]) this variant is found in nearly all dogs. While those breeds are known to have an elevated risk of IVDD, many dogs in those breeds never develop IVDD. For mixed breed dogs and purebreds of other breeds where this variant is not as common, risk for Type I IVDD is greater for individuals with this variant than for similar dogs.

What is Chondrodystrophy and Intervertebral Disc Disease, CDDY/IVDD, Type I IVDD?

Type I Intervertebral Disc Disease (IVDD) is a back/spine issue that refers to a health condition affecting the discs that act as cushions between vertebrae. With Type I IVDD, affected dogs can have a disc event where it ruptures or herniates towards the spinal cord. This pressure on the spinal cord causes neurologic signs which can range from a wobbly gait to impairment of movement. Chondrodystrophy (CDDY) refers to the relative proportion between a dog’s legs and body, wherein the legs are shorter and the body longer. There are multiple different variants that can cause a markedly chondrodystrophic appearance as observed in Dachshunds and Corgis. However, this particular variant is the only one known to also increase the risk for IVDD.

How do I know if my dog will develop this health condition?

Research indicates that dogs with one or two copies of this variant have a similar risk of developing IVDD. However, there are some breeds (e.g. Beagles and Cocker Spaniels, among others [Mini Poodles]) where this variant has been passed down to nearly all dogs of the breed and most do not show overt clinical signs of the disorder. This suggests that there are other genetic and environmental factors (such as weight, mobility, and family history) that contribute to an individual dog’s risk of developing clinical IVDD. Signs of IVDD include neck or back pain, a change in your dog's walking pattern (including dragging of the hind limbs), and paralysis. These signs can be mild to severe, and if your dog starts exhibiting these signs, you should schedule an appointment with your veterinarian for a diagnosis.

What actions can I take?

• Please tell your veterinarian about Puppy’s result.

• Follow veterinary advice for diet, weight management, and daily exercise. Overweight dogs and those with insufficient exercise are thought to be at higher risk of developing clinical disease.

• Ramps up to furniture, avoiding flights of stairs, and using a harness on walks will also help minimize some of the risk of an IVDD event by reducing stress on the back.

• In breeds where this variant is extremely common, this genetic health result should not be a deciding factor when evaluating a dog for breeding or adoption purposes.

The team of Veterinary Geneticists at Embark are here to support you! We can help you understand the potential impact of this health condition and discuss Puppy’s care with your veterinarian. Please feel free to contact us at askthevets@embarkvet.com with any questions or concerns that you may have.

Another point that is important to know is that CDDY is a risk allele, meaning it can increase risk (5%-15%) of IVDD and it is NOT a diagnosis of IVDD. Further, the instance of the diagnosis of IVDD in goldendoodles, bernedoodles, and poodles is extremely low.

Breeders have spent a lot of time researching and discussing this since 2019. Since the instance of IVDD is so low in our breeds, and CDDY is only an associated risk allele, it would be unwise to automatically take out all breeding stock that have CDDY as it would drastically reduce genetic diversity if we did, which come with huge risks. Most breeders are committed to slowly breeding out the CDDY mutation over a couple generations (I am one of these breeders), more out of principle and an abundance of caution over necessity since an IVDD diagnosis is not common in our breeds.

Of course I want you all to have this info, please check with your own veterinarian for your comfort level, but know after research, I also believe if any pups inherit this, it is very low risk for the marker on the allele to turn into a medical diagnosis, especially if you follow the ‘What actions can I take’ points above. If you have any additional questions, please feel free to ask.

**Breeder Edition** Breeders, if you are starting to research this and working through what it means for your breeding program, here is a good place to start. This video is on CDDY/IVDD and CDPA. CDPA is a separate genetic marker and not included on an embark panel. It can most commonly be tested through Paw Print and Animal Genetics.