Hip dysplasia: A debilitating degeneration of the ball-and-socket hip joint. Most common in large dogs, hip dysplasia can run in families of dogs, but it also can occur with no family history of the condition. Other factors include diet (unbalanced, excessive, or deficient), exercise (too much/too little), and traumatic injury.
Ruptured cruciate ligament(s): A tear of one or both of the ligaments that stabilize the knee, causing a painful, debilitating degeneration of the hinged knee joint. Occurs when excessive stress is placed on the knee joint, such as when jumping into a car or pickup truck, pivoting at high speeds, or during ordinary activity in dogs with developmentally unstable knees.
Osteochondritis dissecans, or OCD: The result of improper bone development just beneath the cartilage, causing a "hangnail" of cartilage to peel away from the bone and protrude into the joint. Most common in large breeds during rapid growth, OCD can run in families of dogs, but it also can occur in dogs with no family history of the condition. Other factors include diet (unbalanced, excessive, or deficient), exercise (too much/too little), and traumatic injury during growth.
Spondylitis: A degenerative condition in one or more joints of the spinal column. Results from repeated stress on the joints of the spine in active dogs. It also can occur in dogs that are developmentally predisposed because of unstable joint structure in the spine.
Traumatic joint injury/Joint injury due to trauma: Common causes include falling and forceful impact with a blunt object such as a car.
Geriatric osteoarthritis: A degenerative condition in one or more joints due to aging changes and "wear and tear." Can occur in joints that were harshly used in younger years. It also can be a feature of normal aging, affecting most or all of the joints in the body.