Table 2.

 Potential regions of brain and associated signs in dogs and cats presented for acute onset encephalopathies

Region of brain affected	Potential neurologic signs
Cerebrum/Thalamus	Seizures; changes in sensorium or behavior; circling and other propulsive activity; contralateral postural reaction deficits; contralateral visual impairment with normal pupillary light responses (rarely anisocoria); contralateral hypalgesia (especially nasal).
Midbrain	Depressed sensorium; postural reaction deficits; opisthotonus; mydriasis (+/− anisocoria), abnormal pupillary light responses, normal vision.
Pons/Medulla	Depressed sensorium; gait abnormalities ranging from paresis through recumbency; ipsilateral postural reaction deficits; opisthotonus; multiple cranial nerve deficits including: atrophy of muscles of mastication (V), facial hypalgesia (V), head tilt (VIII), resting or positional nystagmus (VIII), abnormal physiologic nystagmus (III, IV, VI, VIII), resting or positional strabismus (III, IV, VI, VIII), facial paresis or paralysis (VII), dysphagia (IX, X), tongue paresis or paralysis (XII); respiratory or cardiac abnormalities.
Cerebellum	Hypermetric/spastic gait with strength preserved; loss of balance truncal sway; intention tremor of head, neck or eyes; opsithotonus and extensor rigidity of all limbs with hips flexed; menace deficit with normal vision and normal pupillary light responses.