In 2019 results of a study on the genetics of IVDD (Invertibral Disk Disease) was published by the UCDavis research team and created a state of panic among Poodle owners and breeders. Due to well-meaning but not well-researched opinions posted online, IVDD is more concerning to prospective owners than any other potential health issues
Below is the explanation is written By Barbara Hoopes - Colgate University Professor, Molecular biology and Genetics researcher, as well as toy poodle breeder.
Barbara Hoopes:
I've been asked to make a public post on the CDDY/IVDD mutation in poodles because it is upsetting a lot of people. This mutation was found first to be associated with IVDD (Intervertebral Disk Disease) in Tollers by the Bannasch lab at UC Davis. IVDD can cause very serious back issues, and small poodles are known to have a higher risk for this disorder compared to other breeds (Beagles, Cockers, and some other breeds are also at high risk). The same mutation found in Tollers is found at high frequency in these other breeds known to be clinically at higher risk for IVDD. Here is what you need to know as owners or breeders of small poodles:
The CDDY/IVDD mutation is NOT a deterministic mutation, but increases risk, in a dominant fashion. If a dog has two copies of the recessive prcd mutation they WILL go blind. The prcd mutation is deterministic. Dogs with one or two copies of the CDDY/IVDD mutation are at a HIGHER RISK for the disorder, but the MAJORITY of dogs with the mutation will NOT develop IVDD. We don't know the exact risk factor but UC Davis is trying to determine this.
The CDDY/IVDD mutation is found at extremely high frequency in toy and miniature poodles, which undoubtedly explains why they are higher risk. UC Davis estimates that only 16% of dogs would be clear of the mutation, and more than a third of the dogs they tested in their study had two copies. This means that we CAN'T eliminate all dogs with the mutation from our breeding pool! That would eliminate most dogs. This would be BAD.
So what do you do if your dog has one or two copies of the mutation? Be aware that they MIGHT develop IVDD and keep an eye out for symptoms. It is more likely they will be fine. If you can, try to breed them to a dog with which you will get offspring with fewer copies of the mutation. We can eventually move away from the mutation in the breed, but you do NOT want to throw these dogs out of the gene pool if they otherwise are of breeding quality. By restricting the gene pool we would be more likely to select for some other disorder we don't know about by making a "population bottleneck". This isn't just me giving this advice. This is the advice of the group who isolated the mutation, who are veterinary geneticists.
Test your dog at UC Davis, not Embark. The Embark test for CDDY/IVDD does NOT look for the actual mutation, but instead for a "linked haplotype". For toy poodles it is wildly inaccurate--for 24 dogs from three different breeders, only 8 dogs agreed with results from UCDavis (which found the mutation and developed a direct mutation test) and 16 did not agree. This is an ACCURACY rate of only 33%! If you have Embark results, I strongly suggest you test at another company. GenSol and PawPrints also do the test. I will be writing Embark and others about this lack of accuracy.
UCDavis says they have never found this mutation in a standard poodle. However, if your standard has miniature in their pedigree, they could definitely have a copy, since so many small poodles have at least one copy.
Hope this is helpful. I will make my letter to Embark about their test available when it is done.

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