Canine preaxial polydactyly (PPD) in the hind limb is an autosomal dominant disorder known in many dog breeds and it is caused by alterations in the anteroposterior pattering of limb development. It is characterized by congenital malformations of the vertebrate limb and is a developmental trait that restores the digit lost during canine evolution, resulting in abnormal number of digits. An extra digit is usually slightly different from the others with fibrous tissue connecting the region between the tarsal and the first metatarsal bones, which either is reduced in size or incomplete with a lesser deposit of bony material.

Inheritance: autosomal dominant

Mutation: SHH gene

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

DNA test sample: EDTA whole blood (1.0 ml) or buccal swabs. Detailed information about sampling can be found here.