The following are not caused by a single factor, rather genes and environment contribute. Growth rate, nutrition, exercise are some of the components of the development of these disorders.
Patellar luxation: The patella or knee cap moves from side to side. The knee is the complex articulation of the body, consisting of 3 joints with half a dozen critical ligaments and tendons. Small dogs that are encouraged to stand up on the hind legs are vulnerable to injury of this joint.
Elbow dysplasia: Literally “bad formation.” The radius, ulna and humerus do not “fit” together properly. May result from inconsistent growth rates of the three bones.
Hip dysplasia: A similar situation as elbow dysplasia, bones to not fit together properly. Although the spine is not directly included in hip joint, the curvature of the spine is an important factor, a flat topline should be avoided. Standing on the hind legs misaligns the bones and should be discouraged. Elbow and hip dysplasia are forms are arthritis and progress with the age of the dog.