This reflex is observed as a contraction of the cutaneous trunci muscle in response to mild stimulation of the dorsal skin of the trunk. It can be elicited from the thoracic and most of the lumbar region. Regional segmental spinal nerves carry sensory impulses into the spinal cord, where they are relayed cranially to spinal cord segment C8. At this level, a synapse occurs on the LMNs of both lateral thoracic nerves that innervate the cutaneous trunci muscle. This reflex may require multiple attempts to elicit; rarely normal dogs and cats manifest no reflex. This reflex may be particularly useful in diagnosing the level of a transverse thoracolumbar spinal cord lesion or for monitoring a progressive spinal cord injury (e.g., ascending or descending myelomalacia). Typically, the reflex is preserved for one to two vertebral bodies caudal to the level of the spinal cord lesion.