Chondrodystrophy (CDDY) & Chondrodysplasia (CDPA) Suseptibility to Intervertebral Disc Disease (IVDD)
Chondrodysplasia (CDPA) is a general term used to describe a genetic skeletal trait affecting the development of cartilage growth plates. It is generally characterized by a normal sized trunk and shorter than normal limbs.
Chondrodystrophy (CDDY) refers to abnormal cartilage growth and bone development. Many dog breeds like Dachshunds, Bulldogs, Corgis, Pugs, French Bulldogs, Bassett Hounds, Pekineses, Lhasa Apsos, Shih Tzus, Beagles, etc. are defined as having shorter than normal limbs. Other skeletal characteristics that are sometimes associated with chondrodysplasia in dogs are: a lower jaw that may protrude further than normal, an unusually short upper jaw, or over under bite with crooked teeth. Bowed front legs, a crooked spine or breathing problems are also often found to be a problem. In 2009, a discovery found that dogs with CDPA have an autosomal dominant FGF4 insertion on chromosome 18. This promotes the short-legged phenotype. Fibroblast growth factor-4 (FGF4) is a common protein involved in early development on cartilage and bond length. This growth factor is directly correlated to limb development.
In 2017, researchers in the Bannasch Laboratory discovered a second FGF4 insertion on chromosome 12. This insertion is associated with CDDY in dogs with short limbs. It is also associated with the propensity to developmental Intervertebral Disc Disease (IVDD).
Intervertebral Disc Disease (IVDD) is described as premature calcification of the nucleus pulposus. The nucleus pulposus is the inner core of the vertebral disc and is composed of water and a network of collagen fibers. The elastic structure works as a cushion to allow flexibility of the vertebral column. This enables the vertebral column to withstand forces of compression and torsion without damaging the disc. Premature calcification of the nucleus pulposus causes the disc to be less able to adjust to compressions and twists. The nucleus pulposus can then herniate through the protective layer of the annulus fibrosus. It then leaks out of the disc space and inflames the nerve roots next to the disc, causing severe pain and neurological dysfunction or myelopathy. IVDD is a degenerative disease and premature calcification can start in dogs that are less than a year old.
Animal Genetics offers testing for both CDDY and CDPA mutations. The current list of dogs with either CDDY and/or CDPA is not complete and will expand as more testing is completed. CDDY is considered a semi-dominant trait, meaning that dogs with 2 copies of the CDDY mutation are smaller than dogs with only 1 copy of the mutation. CDPA is a dominant trait, meaning that dogs only need a single copy to be affected and to be susceptible to IVDD. Dogs that test positive for both CDDY and CDPA have shorter legs. Research is ongoing to determine if dogs that test positive for CDDY and CDPA are more prone to IVDD then dogs that test positive for only IVDD. Testing can help identify if the dog is at risk for IVDD by distinguishing short legged dogs with CDPA from those with CDDY.
Acceptable Sample Types:
Animal Genetics accepts buccal swab, blood samples, and dewclaw samples for testing. Complimentary sample collection kits are available and can be ordered at test now.
This Test Is Relevant for the Following Breeds:
Basset Hound, Beagle, Bichon Frise, Cardigan Welsh Corgi, Cavalier King Charles Spaniel, Chesapeake Bay Retriever, Chihuahua, American Cocker Spaniel, Coton de Tulear, Dachshund, Dandie Dinmont Terrier, English Springer Spaniel, French Bulldog, Havanese, Jack Russell Terrier, Nova Scotia Duck Tolling Retriever, Pekingese, Pembroke Welsh Corgi, Poodle (Miniature and Toy), Portuguese Water Dog, Scottish Terrier, Shih Tzu.
Results For CDPA:
Animal Genetics offers DNA testing for Chondrodysplasia (CDPA). The genetic test verifies the presence of the mutation and results as one of the following:
|NN/NN||Clear||Dog tested negative for the CDPA mutation.|
|CDPA/n||Affected||Dog tested positive for 1 copy of CDPA and will pass on a copy 50% of the time. Dog will be short-legged.|
|CDPA/CDPA||Affected||Dog tested positive for 2 copies of CDPA and will pass on a copy to 100% of the offspring. Dog will be short-legged.|
Results For CDDY:
Animal Genetics offers DNA testing for Chondrodystrophy (CDDY). The genetic test verifies the presence of the mutation and results as one of the following:
|NN/NN||Clear||Dog tested negative for CDDY mutation.|
|CDDY/N||Affected||Dog tested positive for 1 copy of CDDY and will pass on a copy 50% of the time. Dog will be short-legged and at risk for IVDD.|
|CDDY/CDDY||Affected||Dog tested positive for 2 copies of CDPA and will pass on a copy 100% of the time. Dog will be short-legged and at risk for IVDD.|