Chondrodystrophy (CDDY and IVDD) and Chondrodysplasia (CDPA)

Quick Summary

Chondrodysplasia is a short-legged phenotype characteristic of many dog breeds. Chondrodystrophy, a separate mutation, also includes a short-legged phenotype as well as premature disc degeneration and increased susceptibility to disc herniation.

A short-haired brown Dachshund
Dachshund exhibiting the breed's characteristic short-legged phenotype

Click here for Price and Turnaround Time

Phenotype: Dogs with chondrodysplasia (CDPA) have short legs; this phenotype is characteristic of many breeds such as Corgis and Dachshunds. Chondrodystrophy (CDDY), caused by a separate mutation, also includes a short-legged phenotype as well as abnormal premature degeneration of intervertebral discs (also referred to as intervertebral disc disease, IVDD). These degenerated discs are susceptible to herniation. Multiple factors are thought to influence whether a particular disc herniates in an individual dog. 

Mode of Inheritance:

Chondrodysplasia (CDPA): Autosomal dominant

Chondrodystrophy (CDDY): Autosomal dominant for intervertebral disc disease, semi-dominant for height

Alleles: N = Normal, CDPA = Chondrodysplasia, CDDY = Chondrodystrophy

Breeds appropriate for testing: Alpine Dachsbracke, American Cocker Spaniel, Australian Shepherd, Basset Hound, Bavarian Mountain Hound, Beagle, Bichon Frise, Boykin Spaniel, Cardigan Welsh Corgi, Cavalier King Charles Spaniel, Chesapeake Bay Retriever, Chihuahua, Chinese Crested, Clumber Spaniel, Coton de Tulear, Dachshund, Dandie Dinmont Terrier, Danish Swedish Farmdog, English Springer Spaniel, Entlebucher Mountain Dog, French Bulldog, German Hound, Havanese, Goldendoodle, Jack Russell Terrier, Labradoodle, Maltese, Pekingese, Pembroke Welsh Corgi, Pinscher (Miniature), Poodle (Miniature and Toy), Poodle (Standard), Portuguese Water Dog, Pug, Rat Terrier, Russian Tsvetnaya Bolonka, Schweizer Laufhund, Schweizerischer Niederlaufhund, Scottish Terrier, Sealyham Terrier, Shih Tzu, Skye Terrier, Yorkshire Terrier

(This is not a complete list of breeds. Research on the distribution of this mutation across breeds is ongoing)

Explanation of Results:

►Chondrodysplasia (CDPA):

  • Dogs with N/N genotype will not have this form of chondrodysplasia, which causes the short-legged phenotype of certain dog breeds, and cannot transmit this chondrodysplasia variant to their offspring.
  • Dogs with N/CDPA genotype will have leg shortening compared to N/N dogs. They will transmit this CDPA variant to 50% of their offspring. Matings with N/N dogs are predicted to produce 50% puppies with shortened legs.
  • Dogs with CDPA/CDPA genotype will have leg shortening compared to N/N dogs and will transmit this chondrodysplasia variant to all of their offspring. Matings with any genotype are predicted to produce all puppies with shortened legs.

►Chondrodystrophy (CDDY):

  • Dogs with N/N genotype do not have this chondrodystrophy variant and therefore are not predicted to be at increased risk for intervertebral disc disease. They cannot transmit this chondrodystrophy variant to their offspring.
  • Dogs with N/CDDY genotype will have leg shortening compared to N/N dogs and intervertebral disc disease, and are at risk for intervertebral disc herniation. They will transmit this CDDY variant to 50% of their offspring. Matings with N/N genotype dogs are predicted to produce 50% shorter-legged puppies at risk for intervertebral disc herniation.
  • Dogs with CDDY/CDDY genotype will have leg shortening compared to N/N dogs and intervertebral disc disease, and are at risk for intervertebral disc herniation. If a CDDY/CDDY dog is bred, all of the puppies in the litter will have shorter legs, intervertebral disc disease and will also be at risk for intervertebral disc herniation, regardless of the mate's genotype.

Results of this test can be submitted to the OFA (Orthopedic Foundation for Animals)

Turnaround Time
At least 15 business days; may be delayed beyond 15 business days if sample requires additional testing, or a new sample is requested.
Price

$55 single test per animal ($5 discount on 3 or more dogs)
$25 as additional health test on same animal

Sample Collection

Dog DNA tests are carried out using cells brushed from your dog's cheeks and gums. The preferred cytology brushes are sent to you by mail, or you may provide your own brushes. For accepted alternative brushes, click here

We recommend waiting until puppies are at least three weeks old before testing.

 

Dog having its cheeks and gums brushed for DNA samples
Cheek and gum brushing technique for canine DNA sample collection

Step-By-Step:

  1. Make sure the dog has not had anything to eat or drink for at least 1 hour prior to collecting sample.
  2. When swabbing puppies, isolate each puppy from the mother, littermates and any shared toys for 1 hour prior to swabbing. Puppies should not have nursed or eaten for 1 hour prior to collecting sample.
  3. If collecting samples from more than one dog, make sure to sample one dog at a time and wash your hands before swabbing another dog.
  4. Label brush sleeve with name or ID of dog to be sampled.
  5. Open brush sleeve by arrow and remove one brush by its handle.
  6. Place bristle head between the dog’s gums and cheek and press lightly on the outside of the cheek while rubbing or rotating the brush back and forth for 15 seconds.
  7. Wave the brush in the air for 20 seconds to air dry.
  8. Insert brush back into sleeve.
  9. Repeat steps 5 - 8 for each unused brush in sleeve on a fresh area of cheek and gums. Make sure to use and return all brushes sent by the VGL. In most cases, it will be 3 brushes per dog. If using interdental gum brushes, please note that the VGL requires 4 brushes per dog and only moderate or wide interdental gum brushes are accepted.
  10. Do not seal brushes in sleeve.
  11. Place all samples in an envelope and return to the address provided.

ATTENTION:

  • Do not collect saliva/drool – the key to obtaining a good sample is getting cheek cells on the swab
  • Do not rub swab on the dog’s tongue or teeth – this will result in poor quality sample
  • Do not collect a sample from a puppy that has recently nursed – the mother’s genetic material can rub off on the puppy’s mouth and contaminate the sample
Additional Details
Basset Artésien Normand
Basset Artésien Normand, a short-legged hound breed

Shorter legs in dogs are explained by two retrogene insertions of functional fibroblast growth factor 4 (FGF4). FGF4 gene is involved in many biological processes including bone development.

The first insertion discovered (Parker et al. 2009) is an FGF4-retrogene insertion in dog chromosome 18 (FGF4-18). This FGF4-18 insertion explains a short-legged phenotype known as chondrodysplasia (CDPA) in breeds such as Basset Hound, Pembroke Welsh Corgi, Dachshunds, West Highland White Terriers and Scottish Terriers. CDPA inheritance is considered to follow an autosomal dominant mode.

The Chondrodystrophy (CDDY) mutation was discovered by researchers in the Bannasch Laboratory at the University of California, Davis (Brown et al. 2017) as a second FGF4-retrogene insertion in dog chromosome 12. CDDY includes a short-legged phenotype and abnormal premature degeneration of intervertebral discs leading to susceptibility to Hansen’s type I intervertebral disc disease (IVDD). The intervertebral disc, which sits between vertebrae, is composed of an outer fibrous basket (annulus fibrosus) made of 70% collagen and an inner gel-like layer called the nucleus pulposus. These structures allow for flexibility of the vertebral column. In Chondrodystrophic breeds, premature calcification of the nucleus pulposus at early age (from birth to 1 year of age) results in degeneration of all discs in young dogs. These abnormal discs are predisposed to herniation into the spinal canal where the inflammation, and hemorrhage can cause severe pain and neurological dysfunction (myelopathy) termed Intervertebral Disc Disease or IVDD. IVDD has high mortality rate and high cost of surgical and medical veterinary care.

CDDY is inherited as a semi-dominant trait for height, meaning that dogs with 2 copies of the mutation are smaller than dogs with only 1 copy. With respect to IVDD, the inheritance follows a dominant mode, meaning that 1 copy of the FGF4-12 mutation is sufficient to cause disc degeneration and predispose dogs to disc herniation. Dogs that have both FGF4-12 and FGF4-18 show a more drastic reduction of leg length.

The Veterinary Genetics Laboratory offers a combined test for CDDY and CDPA for breeds that have long and short leg phenotypes. Our tests assay for the causal variants, not for linked markers, therefore the genotypes are accurate and not inferred. CDDY and CDPA occur in many breeds. Testing for these mutations can help breeders determine if CDDY is present among breeding stock and to identify dogs at risk for IVDD. In breeds where both mutations are present, breeders can benefit from test results to implement breeding strategies to reduce incidence of CDDY, while retaining the short-legged phenotype conferred by CDPA.

The CDDY variant has been found in many breeds such as Alpine Dachsbracke, American Cocker Spaniel, Australian Shepherd, Basset Hound, Bavarian Mountain Hound, Beagle, Bichon Frise, Boykin Spaniel, Cardigan Welsh Corgi, Cavalier King Charles Spaniel, Chesapeake Bay Retriever, Chihuahua, Chinese Crested, Clumber Spaniel, Coton de Tulear, Dachshund, Dandie Dinmont Terrier, Danish Swedish Farmdog, English Springer Spaniel, Entlebucher Mountain Dog, French Bulldog, German Hound, Havanese, Jack Russell Terrier, Maltese, Nova Scotia Duck Tolling Retriever, Pekingese, Pembroke Welsh Corgi, Pinscher (Miniature), Poodle (Miniature and Toy), Poodle (Standard), Portuguese Water Dog, Pug, Rat Terrier, Russian Tsvetnaya Bolonka, Schweizer Laufhund, Schweizerischer Niederlaufhund, Scottish Terrier, Sealyham Terrier, Shih Tzu, Skye Terrier, and Yorkshire Terrier. This is not a complete list of breeds.

A comprehensive study was recently completed by Batcher and colleagues 2019 to investigate the breed distribution. (https://doi.org/10.3390/genes10060435) In addition, the VGL has compiled allele frequencies for various breeds based on testing done at our laboratory. These data can be found in the following table, and we will update this table periodically as more dogs are tested.

The table below shows the allele frequency of CDDY in 64 dog breeds for which at least 30 dogs have been tested. Dogs included in the calculation were tested at the VGL and closely related individuals (such as owner-reported siblings or half-siblings) were removed from the calculation.
Breed* Frequency of CDDY** 95% Confidence Interval
>1000 dogs tested French Bulldog 0.9118 0.9087 to 0.9148
  Nova Scotia Duck Tolling Retriever 0.3471 0.3313 to 0.3633
  Pug 0.0072 0.0044 to 0.0118
  English Bulldog 0.0036 0.0016 to 0.0076
  Dalmatian 0.0017 0.0001 to 0.0067
  Coton de Tulear 0.4219 0.3955 to 0.4487
  Dachshund 0.9179 0.9074 to 0.9283
  Portuguese Water Dog 0.1262 0.1025 to 0.1544
  Bulldog 0.1573 0.1387 to 0.1780
500-999 dogs tested Pembroke Welsh Corgi 0.8323 0.8109 to 0.8517
  Poodle, Standard 0.0875 0.0689 to 0.1105
  Havanese 0.0967 0.0743 to 0.1247
100-499 dogs tested Poodle, Miniature 0.6127 0.5746 to 0.6494
  Boston Terrier 0.0169 0.0080 to 0.0337
  Labrador Retriever 0.0161 0.0066 to 0.0356
  Weimaraner 0.0059 0.0002 to 0.0226
  Boykin Spaniel 0.5775 0.5269 to 0.6266
  Goldendoodle 0.2760 0.2326 to 0.3240
  Beagle 0.9482 0.9180 to 0.9679
  German Shorthaired Pointer 0.0035 0.0001 to 0.0219
  Rottweiler 0 0.0000 to 0.0179
  Great Dane 0 0.0000 to 0.0140
  Poodle, Toy 0.5993 0.5400 to 0.6557
  Doberman Pinscher 0 0.0000 to 0.0201
  Biewer Terrier 0.1372 0.0979 to 0.1885
  Australian Shepherd 0.0292 0.0152 to 0.0537
  American Pit Bull Terrier 0.0045 0.0001 to 0.0279
  Rat Terrier 0.0172 0.0036 to 0.0518
  German Shepherd 0 0.0000 to 0.0205
  Golden Retriever 0.0084 0.0003 to 0.0321
  Cardigan Welsh Corgi 0.8485 0.7915 to 0.8922
  Shiba Inu 0 0.0000 to 0.0263
  Bernese Mountain Dog 0.0040 0.0001 to 0.0244
  Jack Russell Terrier 0.0461 0.0208 to 0.0937
  Akita: Japanese type 0 0.0000 to 0.0373
  Chesapeake Bay Retriever 0.0783 0.0453 to 0.1304
  Alaskan Malamute 0 0.0000 to 0.0356
  Cavalier King Charles Spaniel 0.9957 0.9733 to 1.0000
  Catahoula Leopard Dog 0 0.0000 to 0.0293
  Wirehaired Vizsla 0 0.0000 to 0.0373
30-99 dogs tested Belgian Malinois 0 0.0000 to 0.0246
  Olde English Bulldogge 0 0.0000 to 0.0317
  Pomeranian 0.0071 0.0001 to 0.0434
  Miniature American Shepherd 0.0606 0.0293 to 0.1168
  Pit Bull 0.0203 0.0042 to 0.0606
  Italian Greyhound 0 0.0000 to 0.0321
  Siberian Husky 0.0076 0.0001 to 0.0459
  Shih Tzu 0.1610 0.1047 to 0.2387
  American Bully 0.0948 0.0523 to 0.1633
  Chinese Crested 0.3846 0.2844 to 0.4957
  Australian Labradoodle 0.5000 0.3954 to 0.6046
  Danish/Swedish Farmdog 0.2073 0.1327 to 0.3081
  Yorkshire Terrier 0.1552 0.0996 to 0.2329
  Alaskan Klee Kai 0.0286 0.0020 to 0.1042
  Rhodesian Ridgeback 0.0100 0.0001 to 0.0599
  Akita: American type 0 0.0000 to 0.0607
  English Cocker Spaniel 0.8846 0.8076 to 0.9342
  Border Collie 0.0089 0.0001 to 0.0538
  Black Russian Terrier 0 0.0000 to 0.0698
  Labradoodle 0.3939 0.2849 to 0.5147
  Irish Setter 0.0114 0.0001 to 0.0677
  Sealyham Terrier 0.7241 0.5971 to 0.8233
  American Bulldog 0.0694 0.0264 to 0.1561
  Giant Schnauzer 0.0161 0.0001 to 0.0941
 

Note: Table updated on 09/16/2024

* Breeds were, in most instances, owner reported.

** Frequency of the CDDY mutation in dogs tested at the VGL. Allele frequencies are represented as decimals and range from 0 to 1, where 1 means that 100% of all dogs tested had the same allele.

Recommendations on Testing: For those breeds in which CDDY has been documented to segregate, in other words, both the CDDY allele and the normal allele are present in the breed, genetic testing is recommended. The results of this test can assist in breeding decisions and should be shared with the animal’s veterinarian to assist in clinical decisions. The CDDY allele has been found to be present in mixed breed dogs and therefore testing is recommended for these animals as well. For breeds where the CDDY allele is fixed in the population, in other words only the CDDY is present or allele frequency is 1.0, genetic testing for CDDY is not necessary, in these cases it is reasonable to assume that all dogs in that breed will be homozygous for CDDY (CDDY/CDDY).

For more information on recommendations on genetic testing and counseling, please see this article written by Drs. Bannasch and Bellone.