HistoryA 10-year-old spayed female Labrador Retriever was evaluated for lethargy and unwillingness to climb stairs of approximately 4 weeks' duration. On physical examination, manipulation of the cervical portion of the vertebral column elicited signs of discomfort and the dog was reluctant to lift its head. Additionally, there was mild ataxia of all limbs and an intermittent non-weight-bearing lameness of the right fore limb. Survey radiographs of the cervical portion of the vertebral column were obtained (Figure 1). Determine whether additional imaging studies are required, or make your diagnosis from Figure 1-then turn the page * * Figure 1-Right lateral radiographic view of the cervical portion of the vertebral column of a 10-year-old spayed female Labrador Retriever evaluated for lethargy, unwillingness to climb stairs, and mild ataxia of approximately 4 weeks' duration.