Start with a clean root at the pelvis, then lay out spine segments as separate bones, each a child of the previous. Keep the hierarchy in one straight line so each bone’s transform is purely a function of its parent. Name them systematically – spine_01, spine_02, … – so you never waste time guessing. Don’t forget to lock the rotation order to XYZ; it prevents that annoying flip‑flop. Use quaternion interpolation for the joints; it gives the smooth, continuous twist you’ll get from a real deer. Finally, test the rig with a quick walk cycle – if any bone’s axis feels off, rebuild it, not your entire chain.

Yeah, give each bone a tiny amount of weight so the mesh can bend like a real spine. Keep the weights gradual along the chain – it prevents that stiff kink you see when you over‑weight one joint. A quick gradient from the root to the tip will make the stretch feel natural without overcomplicating the paint.