Answer 9

In the pelvic limb, the withdrawal reflex evaluates the integrity of the spinal cord segments L4 to S1 (and associated nerve roots), the femoral and sciatic nerves, and the muscle innervated. A noxious stimulus is applied to the tested limb by pinching the nail bed or digit with the fingers or a haemostat. This stimulus causes a reflex contraction of the flexor muscles and withdrawal of the tested limb. Spinal reflexes such as the withdrawal reflex are SEGMENTAL. They only evaluate the spinal segment(s) within the intumescences corresponding to the stimulated nerve. They do NOT require consciousness. Nociception is tested by pinching the digits with the fingers or with haemostats. Only a behavioural response to noxious stimulus (turning of the head, attempt to bite) indicates conscious pain perception. Withdrawal of the limb is only the flexor reflex and should not be taken as evidence of pain sensation. Nociception is the most important prognostic indicator of severity that can be obtained from the neurological examination of an acutely paralysed animal.

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