A five week old intact female Flat-Coated Retriever presented to the Cornell University Hospital for Animals Emergency Service following an unwitnessed acute traumatic cervical injury. The following morning, the patient was transferred to the Neurology Service. Abnormalities detected on neurologic examination neurolocalized to a C1-C5 myelopathy, which was later confirmed on advanced imaging modalities. This senior seminar will focus on the diagnosis and surgical treatment of atlantoaxial instability (AAI) using advanced imaging modalities such as CT (computed tomography) and MRI (magnetic resonance imaging). Both congenital and traumatic AAI will be discussed.