Ligament and tendon pathology is rarely diagnosed in guinea pigs, whereas muscles may be involved in trauma and infection. Pathology of bone is the most common musculoskeletal presentation, with joint pathology being frequently diagnosed, especially in ageing guinea pigs. This chapter provides guidance on the anatomy and physiology, clinical signs, diagnostic investigations and treatment of a range of musculoskeletal diseases in guinea pigs. The chapter covers conservative management of fractures; surgical management is covered in Chapter 13.