Diseases of the nervous system in domestic animals present with diverse clinical signs depending on lesion site and severity.

Motor deficits include paresis (weakness with stumbling or dragging), paralysis/plegia (complete loss of voluntary movement), and ataxia (incoordination with a wide stance, swaying, circling, or hypermetria). Other findings are tremors and seizures marked by sudden collapse, paddling, or loss of consciousness. Sensory deficits range from hypoesthesia/anesthesia (reduced or absent sensation) to hyperesthesia (exaggerated pain response).

Cranial nerve deficits are common: facial paralysis (drooping ear, lip, eyelid), vestibular signs (head tilt, nystagmus, circling), vision loss, and dysphagia. Behavioral changes include dullness, stupor, coma, aggression, compulsive circling, and head pressing.

A neurological examination is essential for lesion localization and diagnosis. Initial observation assesses mental status, posture, gait, and involuntary movements. Gait and posture analysis tests ataxia, paresis, head tilt, circling, and spinal curvature using maneuvers like circling, backing, or obstacle walking.

Cranial nerve examination evaluates all 12 nerves: smell (I), vision/PLR (II), ocular movement and nystagmus (III, IV, VI), mastication and sensation (V), facial symmetry and eyelid/lip movement (VII), balance and hearing (VIII), swallowing and gag reflex (IX, X), neck muscle tone (XI), and tongue function (XII).

Spinal reflexes (withdrawal, patellar, perineal, cutaneous trunci) help assess spinal cord segments. Proprioception is tested by hopping, paw placing, or wheelbarrowing for delayed or incorrect limb placement. Palpation identifies spinal pain, muscle atrophy, or other abnormalities, aiding in narrowing the diagnosis.