 Among these are hip dysplasia and osteochondritis dissecans (OCD), conditions most common in medium to large purebred dogs, such as German Shepherds, Labrador Retrievers or Golden Retrievers; chronic degenerative radiculomyelopathy (CDRM), a degenerative disease of the spinal cord which causes hind limb problems in German Shepherds; and luxating patella which is seen predominantly in small and toy breeds.Injuries to the cruciate ligament or other ligaments may make post-operative weight-bearing exercise in dogs problematic.Obese dogs, while requiring exercise, may aggravate existing conditions or injure themselves due to the weight exerted on their joints if walked normally.