Osteogenesis imperfecta (OI) is an inherited Collagen disorder affecting dogs. Affected dogs typically present between 3 to 4 weeks of age with pain, lameness and fractures. OI is caused by a defect is in the way collagen is made. Because collagen is an important component of bone, bones of affected dogs are thinner than normal, fracture easily and do not heal properly. Other features of the disorder include loose joints and brittle teeth. Because of the severity of the disease, pups with OI are usually euthanized by 3 months of age.