Final answer:
The spine or vertebral column of a dog runs just beneath its back, along the dorsal side, and is enclosed within the spinal cavity. It provides protection for the spinal cord, supports the head, and serves as an anchor for back muscles.
Step-by-step explanation:
The question pertains to the anatomy of a dog, specifically to the structure and position of the spine or vertebral column and its relation to the dog's body. Dogs, like other mammals, have a spinal cavity that is enclosed within the vertebral column, which runs the length of the trunk and contains the spinal cord. The vertebral column is crucial as it surrounds and protects the spinal cord, supports the head, and serves as an attachment point for ribs and muscles of the back and neck.
Moreover, the dorsal hollow nerve cord, which in some animals develops into the brain and spinal cord, runs along the top or dorsal side of the animal. The top of the spinal cord itself is a bundle of nerves that merges with the brain stem. While the brain stem controls basic life processes, the rest of the spinal cord descends down through the vertebral column and ends just below the ribs, as it does not extend to the base of the spine.
In conclusion, a dog's spine runs just beneath its back, along the dorsal side, fitting within the protective enclosure of its vertebral column, which is approximately 70 cm (28 in) in adult dogs and correctly curved when viewed from the side, providing structural support for muscle attachment and protection for the spinal cord.