Medial Shoulder Instability

Medial shoulder instability refers to a condition in which the structures that normally hold the shoulder joint in position on its inner side become lax or damaged, allowing abnormal movement or partial displacement of the joint during activity. This can occur after injury to ligaments, tendons, or the joint capsule, or it may develop gradually in some dogs without a clear inciting event. Owners often notice lameness that may be subtle at first, sometimes appearing after exercise or play and improving with rest. The leg may appear to be carried differently, or the dog may show reluctance to bear weight fully on the affected limb. In some cases, the shoulder may feel unstable or appear to shift when the limb is moved in certain directions. This page explores the observable signs that may suggest shoulder instability, the anatomical changes that underlie the condition, the investigations used to assess the joint, and the range of approaches—both conservative and surgical—that exist for managing it. The information is intended to help you understand what may be happening and what questions might be useful to consider.