Evaluation of the Trunk, Pelvic Limbs, Anus, and Tail

Cutaneous Trunci and Panniculus Reflex

Postural Reactions

Spinal Reflexes

Muscle Atrophy

Sensation

Schiff-Sherrington Phenomenon

The trunk of the animal is observed for abnormal posture or deviation of the vertebral column, pain, desensitization or hyperesthesia to light pinpricking, and focal muscle atrophy.

Cutaneous Trunci and Panniculus Reflex:

Pinpricks applied to the skin of the thorax and abdomen result in contraction of the cutaneous trunci muscle. This reflex arc includes the afferent cutaneous branches of the lumbar and thoracic spinal nerves, a spinal cord tract that ascends to T2, and the LMN in the lateral thoracic nerve to cutaneous trunci muscles. The reflex is used to localize spinal cord lesions between the site of afferent stimulation and T2.

Postural Reactions:

Wheelbarrowing, proprioceptive positioning, placing, and hopping are evaluated on the pelvic limbs in a manner similar to that used for the thoracic limbs. As with the thoracic limbs, these tests require complete integrity of the brain, spinal cord, and peripheral nerves; thus, they are not useful for localizing lesions but are useful in detecting subtle deficits that support the presence of a neurologic lesion.

Spinal Reflexes:

The pelvic limb spinal reflexes are more reliable for localizing thoracolumbar lesions than are the thoracic limb reflexes. Spinal reflexes are normal or exaggerated with lesions above the reflex arc and are depressed or absent with lesions at the level of the reflex. Percussion of the patellar tendon should cause the stifle to extend if L4-L5 spinal cord segments and the femoral nerve are intact. Percussion of the gastrocnemius and cranial tibial muscles causes the hock to extend or flex, respectively, and tests the tibial and peroneal nerves, lumbosacral plexus, and L6 to S2 spinal cord segments. A crossed extensor reflex may be associated with lesions above L6. When the anus is pinched or pricked with a pin, the sphincter tightens and the tail pulls down if S1-S3 (anus) and caudal (Cd) tail segments and nerves are intact. An atonic (areflexic) bladder, anus, and tail are seen with lesions affecting S1 to Cd5 or the cauda equina.

Muscle Atrophy:

Focal muscle atrophy of the trunk or pelvic limb localizes a lesion to the nerve that innervates that muscle.

Sensation:

In moderate to severe spinal cord lesions, superficial sensation may be absent from the cranial aspect of the lesion caudally. In severe spinal cord lesions, deep pain is absent from the periosteum of all toes and the tail.

Schiff-Sherrington Phenomenon:

In some animals with acute, severe lesions of the spinal cord between T2 and L3, the pelvic limb paralysis is accompanied by an extensor rigidity of the thoracic limbs when the animal is in lateral recumbency. Although a severe lesion produces this syndrome, the prognosis is probably not hopeless if deep pain can be elicited.