Hypothesis #3 Congenital Joint deformity Again, the breed basically points to this. Large breed dogs, rottweillers, german shepherds, and labradors in particular are susceptible to hip dysplasia and other congenital bone abnormalities (panosteitis, OCD, etc.) while the evidence points to the hip joint, we can not be definitive yet. But some type of congenital disease should be on the rule out list.