Overview
Cattle have 18 to 20 caudal vertebrae (vertebrae caudales), which form the skeleton of the tail. They decrease in size and complexity from cranial to caudal: the first ones resemble the other vertebrae, whereas the last are simple bony rods. The first articulates with the apex of the sacrum.
Key features
- First caudal vertebrae: keep a body, vertebral arch, small spinous processes and wide transverse processes.
- Haemal arches (arcus haemales): on the ventral surface of the first caudal vertebrae; they form a canal that protects the median caudal artery and vein, which run along the ventral midline of the tail.
- Distal caudal vertebrae: lose the arch and processes and are reduced to ever smaller cylindrical bodies.
- Intercoccygeal joints: the intervertebral discs make the tail very mobile; the first movable space, between Cd1 and Cd2, is located by moving the tail up and down.
Clinical relevance
- Blood sampling: the median caudal vein is punctured on the ventral midline of the proximal third of the tail, avoiding the haemal arches; it is the usual route in dairy cattle. The pulse of the median caudal artery is taken at the same site.
- Caudal epidural anaesthesia: given at the Cd1–Cd2 space or at the sacrococcygeal space.
- Tail fractures and trauma: common from being stepped on, trapped or restrained by the tail with excessive force; they can cause tail deviation, necrosis of the distal tail or paralysis.