Chondrodysplasia, Intervertebral Disc Disease Risk Factor and Chondrodystrophy (CDPA/CDDY – IVDD)

One of the most prominent characteristics defining many dog breeds are extremely short limbs. This morphological feature is the result of abnormal growth of developing limbs due to defects in the process of endochondral ossification. Short limbs were associated with two conditions: chondrodysplasia and chondrodystrophy. Chondrodysplasia (CDPA) is defined as an inherited condition characterized by abnormal growth at the ends of bones, particularly the long bones. In dogs CDPA was associated with FGF4 gene insertion on chromosome 18, which is inherited as autosomal dominant trait and found to cause short legged phenotype in Basset Hound, Welsh Corgi, Dachshund, West Highland White Terrier and Scottish Terrier. Chondrodystrophy (CDDY) in dogs is defined by dysplastic, shortened long bones and premature degeneration and calcification of intervertebral discs- type I intervertebral disc disease (IVDD). Abnormal discs are predisposed to herniation leading to IVDD in dogs at young age. CDDY/IVDD was associated with FGF4 gene insertion on chromosome 12, which is inherited in semi-dominant manner in respect to height (dogs with 2 copies of the mutation have shorter legs than dogs with one copy of the mutation) and dominant for IVDD (dogs with one or two copies of the mutation are at risk for IVDD). This mutation was found in many dog breeds.

Inheritance: autosomal dominant

Mutation: FGF4 gene

Genetic test: The method used for testing is extremely accurate and allows complete differentiation between affected animals, carriers and healthy dogs. Testing can be done at any age.