The hereditary skeletal disease of folded-eared cats is called chondrooskeletal dysplasia. The main symptoms are that the tail will be relatively thick, short and stiff. In severe cases, the tail of folded-eared cats cannot swing freely, and then the bones and joints of the hind limbs will develop. Abnormalities, deformed and bent foot bones, and swollen bones and joints in the soles of the feet. Similar symptoms may also occur in the forelimbs, but to a lesser extent than in the hind limbs. Some cats' toes may even become deformed, their claws cannot extend and contract normally, their nails may grow abnormally, and their hind feet may become abnormally thick.