Osteogenesis imperfecta is a form of osteochondrodysplasia of genetic origin in which bones break easily. Sometimes the bones break for no known reason. The condition can also cause weak muscles, brittle teeth, a curved spine and hearing loss. The cause is a gene defect that affects how the body makes collagen, a protein that helps make bones strong. Usually humans and animals inherit the faulty gene from a parent. Sometimes, it is due to a mutation, a random gene change. Osteogenesis imperfecta can range from mild to severe and symptoms vary from one individual to another. Osteogenesis imperfecta is a well-documented inherited disorder in children, but has rarely been described in animals. In humans, the clinical disease is characterized by brittle bones with spontaneous fractures, sometimes combined with deformities, dwarfism, and brittle teeth. In dogs, osteogenesis imperfecta has been reported in Golden Retrievers, Collies, Poodles, Beagles, Norwegian Elkhounds, and Bedlington Terriers. Young animals are mostly affected during the first few weeks of life. There is no cure for this disorder.
When a young dog is evaluated for multiple fractures with minimal to no accompanying trauma, osteogenesis imperfecta is suspected. The diagnosis is based on analyzing type I collagen from cultured skin cells (fibroblasts) and confirmed by radiographic findings showing multiple bone fractures in various stages of healing. Clinical signs consist of pain, spontaneous bone and teeth fractures, loose joints, and reduced bone density on radiography. Primary teeth are extremely thin-walled and brittle.