In 2017 the University of California Davis (UC Davis) discovered a mutation in a gene that is associated with intervertebral disc disease (IVDD) in dogs. The mutation is known as CDDY.
In 2019 another study was performed that investigated prevalence of this gene in different breeds. Also in 2019, commercial tests for CDDY became available, which meant that for the first time we as breeders could test for this mutation.
Until the mutation began to show up on routine genetic screening panels starting in late 2019, we were not even aware of its existence since it is such a rare disease in Goldendoodles.
As a breed whose breed association (the Goldendoodle Association—GANA) and breeders take health clearances and structurally sound dogs very seriously, we were crushed by this news.
In fact, at first, we panicked.
Then we went on a learning binge.
Individual breeders, including us, as well as GANA consulted researchers and both molecular genetics and population genetics experts, including extensive discussions hosted by GANA with Dr Robert Grahn (Associate Director of the Veterinary Genetics Lab at UC Davis), Dr. Jerold Bell (Canine population genetics expert, Tufts University Cummings School of Veterinary Medicine), and Dr. Casey Carl (molecular geneticist, PawPrint Genetics).
About the CDDY mutation
The CDDY mutation is a risk allele, not a causative allele. That means it increases risk, but it is NOT shown to cause IVDD.
In general the mutation causes a 5-15% greater risk of IVDD, depending on breed. Based on what we know of over a decade of records from GANA breeders, there is a very, very small incidence of IVDD in our breed and we are well on the lower end of this risk range.
The lack of IVDD in our breed is likely because the conformation of our dogs does NOT lend itself to luxation in the spine (this is per Dr. Robert Grahn at UC Davis).
Recommended course of action
We do have the mutation in a high frequency in our breed. Not as high as Beagles, but it is very prevalent in our breed.
That means about half of Goldendoodles have this mutation, although we have very, very few reports of actual disc disease in our breed.
There is clear consensus from the experts that removing the mutation from the gene pool too quickly and without careful planning will be very harmful for the breed and the gene pool. In fact, we have been told it would be better for the breed for us to NOT remove the gene than to remove it hastily or without careful planning.
The advice from the experts we have consulted has consistently been:
We should remove it not out of necessity but out of an abundance of caution, but we should not remove it at the expense of the genetic health of our breed.
It took a long time to get the gene dispersed into the gene pool and to remove it safely we should take a long time to breed it out.
Our goal should be to remove this from the gene pool over 5-10 years.
To remove it safely without damaging the gene pool the advice we received from the experts we consulted is to only use it as a “tie breaker” between two otherwise well-qualified breeding dogs and to NOT remove dogs from our programs simply because of CDDY status.
We plan to follow these recommendations in our program.
We need to remember that by breeding this out too quickly we could inadvertently be causing more harm than good that could be far worse than the CDDY mutation, therefore we must do this with care and thought.
The advice we have received from UC Davis to reduce risk is:
Keep your dog in good shape.
Keep them fit and active.
Keep them at a healthy weight.
Avoid high impact activities.
These are all things most good breeders encourage or even include in their contract/warranty and these are the same recommendations for prevention of canine hip dysplasia.
Brown, E.A., Dickinson, P.J., Mansour, T., Sturges, B.K., Aguilar, M., Young, A.E., Korff, C., Lind, J., Ettinger, C.L., Varon, S., Pollard, R., Brown, C.T., Raudsepp, T., & Bannasch, D.L. (2017). FGF4 retrogene on CFA12 is responsible for chondrodystrophy and intervertebral disc disease in dogs. Proceedings of the National Academy of Sciences of the United States of America, 114(43), 11476-11481. doi: 10.1073/pnas.1709082114
Batcher, K., Dickinson, P., Giuffrida, M., Sturges, B., Vernau, K., Knipe, M., Rasouliha, S.H., Drögemüller, C., Leeb, T., Maciejczyk, K., Jenkins, C.A., Mellersh, C., & Bannasch, D. (2019). Phenotypic Effects of FGF4 Retrogenes on Intervertebral Disc Disease in Dogs. Genes, 10 435. doi: 10.3390/genes.10060435