Shoulder instability is one of the most common causes of lameness in the forelegs of dogs and cats. The parts of the shoulder primarily responsible for shoulder stability are the joint capsule and the collateral ligaments. These can be injured mostly due to overuse, but can also be caused by severe trauma or repeated smaller traumas. Degenerative joint disease can also be a factor in some cases. Some symptoms can include a lingering limp, pain while extending shoulder and decreased range of motion.

Shoulder instability typically affects medium and larger dog breeds that tend to be hyperactive, but can also affect cats. A veterinarian may sedate an animal in order to examine them and determine the severity of their injuries. Shoulder instability can be treated surgically and nonsurgically. For more severe cases, arthroscopic surgery is usually required.