Calving-related intradural avulsion injuries of the thoracolumbar spinal nerve roots in a calf.

Calving difficulty may lead to traumatic peripheral nerve injury. A male, 8-mo-old, Japanese Black calf with a history of secondary dystocia as a result of fetal gigantism had lameness and gait disturbance. At autopsy, multifocal dural thickening with adhesions to the adjacent spinal cord was observed at T12-13 and L4-5 vertebral levels. Microscopically, numerous traumatic neuroma-like fascicles of nerve twigs were embedded in the dura mater with abundant collagenous connective tissue. By immunohistochemistry, axons and Schwann cells were confirmed in each nerve fascicle. Our observations suggest that avulsion injuries in the preganglionic fibers of the spinal nerve roots, and secondary spinal cord compression, resulted in the development of neurologic signs.