CDDY and PRA are common genetic traits among dogs. What are they, and what do they mean for your puppy?
When we learned that our puppies India and Zara have one copy of a gene that can pass “CDDY” to their offspring, I thought we would have to find other females for our breeding program. But our concerns were quickly put to rest.
How has our experience given us the confidence to move forward with our breeding program? Why should you want to buy a puppy from genetically health tested parents? What does India and Zara’s copy of CDDY and Zara’s one copy of PRA mean for their puppies? And what, exactly, are CDDY and PRA?
Our Experience with CDDY and PRA
We have done extensive genetic testing on our dogs. Even though they came from health tested parents, we wanted our own results. In Zara’s case, her parents were tested with just a poodle panel. However, this panel tests only for the four most common genetic diseases in poodles and does not include tests for conditions like CDDY.
Some breeders perform no genetic testing at all. I lost count of the number of times during my search for our breeding dogs that I was told, “We don’t do genetic health testing. But I’ve been breeding for [insert 3, 4, or 5!] years, and we haven’t had any issues.”
To my ears, that position was unjustified. We wanted to do better. Our experience spurred us on in two ways:
First, it reinforced our purpose to offer only puppies who themselves are from fully genetically health tested parents. I believe all breeders should be conducting genetic health tests. It saves so much suffering and heartache later. As an example, a breeder could be pairing two dogs that each have a copy of “PRA.” That means their puppies could potentially go blind in 3 to 9 years!
Second, it gave us the confidence to keep India and Zara in our breeding program. Otherwise, the decision to breed only CDDY-free dogs can do more harm than good. (More on that below.) Since our male, Beau, tested clear for everything, we could trust in the laws of genetics in regard to pairing him with our girls. In fact, if I could clone Zara, I would. Her temperament is just that amazing!
We are very thankful for the many experienced breeders and veterinarians who supported us through this experience. With their advice, we kept India and Zara in our program. And we are so happy we did! Let’s understand a little more about what CDDY is, and how our concerns over it were lifted….
CDDY – Chondrodystrophy
CDDY stands for “chondrodystrophy.” It is a common trait identified in many dog breeds, including miniature poodles. It is characterized by shortened length of the limbs, which is a result of early changes in the structure of the growth plates.
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 appear on routine genetic screening panels starting in late 2019, we were not even aware of its existence. So miniature poodles had been bred for decades without breeders knowing that this allele was in their pedigree.
In personally speaking with a veterinarian from Paw Print Genetics, I was advised against removing a dog from my program that had CDDY but was otherwise suited for breeding. He said that only breeding CDDY-clear dogs would significantly and detrimentally reduce the gene pool of miniature poodles, limiting their genetic diversity.
He also stated that the reason miniature poodles have the potential to have one or two copies of CDDY is because they were bred down in size from standard poodles, adding ironically that concern over CDDY is equivalent to concern over their being “miniature.”
The CDDY genetic mutation is only one of the causes of the trait for short legs in some dog breeds. The other cause is chondrodysplasia (CDPA), also known as short-limbed or disproportional dwarfism.
CDPA is common in breeds such as dachshunds and is why you will sometimes see them in wheel-carts to help them remain mobile. Bee Haven dogs do not have CDPA.
The CDDY mutation is also responsible for intervertebral disc disease (IVDD). It’s important to understand that having CDDY does not mean that a dog will develop IVDD. It simply means that a dog is at risk for developing it. The advice we received from UC Davis to reduce risk of IVDD in dogs is:
- Keep them fit and active
- Keep them at a health weight
- Avoid high impact activities
The CDDY mutation is a risk allele, not a causative allele. That means it increases risk, but it is NOT shown to cause IVDD.
Many factors come into play regarding the potential development for IVDD. These including activities, exercise, and weight. For example, a dog that often jumps down from high surfaces, even at a young age, or is overweight is more at risk for developing IVDD.
PRA – Progressive Retinal Atrophy
Progressive retinal atrophy (PRA), is a group of degenerative diseases that affect the eye. With this disease, certain cells deteriorate over time, eventually leading to blindness in the affected dog.
In general, PRA is an inherited disease that occurs in many breeds of dogs (including poodles and Australian shepherds) and also occurs in mixed breeds. In the majority of dogs, it appears to be inherited in an ‘autosomal recessive’ pattern, meaning that the affected dog must have inherited the defective gene from both parents.
Zara is our only dog that carries one copy and she will only ever be bred to a male that is clear of it. That means PRA will never affect her or her puppies, but they may inherit one copy just like Zara.