Abnormal formation of a bodily structure or tissue, usually bone, that may occur in any part of the body.
Several types are well-defined diseases in humans. In the most common, epiphyseal dysplasia, the ends of children's bones (epiphyses) grow and harden very slowly; dwarfism often results (sometimes only in the legs), and degenerative joint disease usually develops by middle age. Large dogs bred for narrow hips may have hip dysplasia, with abnormalities involving the head of the thighbone and the hip socket.