The spinal nerves, T13, L1, and L2 must be blocked to completely desensitize the flank of a cow.
The paravertebral (PV) nerve block targets these nerves. It can be performed via two techniques â the proximal or distal PV block.
The proximal block places local anesthetic in the space just caudal to the transverse processes of the vertebrae – T13, L1, and L2.
The distal block is placed at the ends of the transverse processes of the vertebrae â L1, L2, and L4 as the nerves gradually course caudally after they exit the spinal foramen.
Proper placement of the anesthetic results in warming of the skin from vasodilation, anesthesia of the skin and body wall, and a curvature of the spine in some cows.
The latter is caused by relaxation of the epaxial musculature on the affected side; the spine curves in a convex manner.
Click here for a useful review of Local Anesthesia and Analgesia by Lyon Lee DVM, PhD. pp. 12-14.
