Large Animal Neurology. Joe Mayhew

neurologic examination, with only then careful reflection on the significance of the findings, that successful and accurate diagnoses are made.

       If all else fails, examine the patient again!

Table 2.2 Outline of basic format for the neurologic examination, based on that for the horse

Region	Evaluation	Sites evaluated	Points to emphasize
Adult	Neonate <2 weeks
Head	Behavior	Forebrain	History and owner’s understanding Seizures, especially mild and focal. VIDEO Subtle asymmetry in menace and nasal sensation	Quick adjustment ~2–7 days Paralytic state with cradling Partial seizures—just face, jaw
	Mentation/sensorium	Forebrain Midbrain	Response to environment Sleep attacks more common than epilepsy Cardiovascular syncope very rare	Adjustment ~24 h
	Head posture and movement	Neck Forebrain—head and neck turn Vestibular—head tilt Tremor—check eyeballs	Stiff/twisted neck Head tilt (VIII) verses head turn (forebrain) Head tremor—cerebellar Head/neck ataxia—cerebellar/spinal Head shaking—trigeminal	Flexed head posture and ataxic movements normal
	Cranial innervation	CN II – XII Brainstem Cervical sympathetic supply	Evaluate regions of head Fundic examination Repeat test for subtle asymmetries Reevaluate when totally relaxed	Menace deficit <7 days Eye rotation dorsomedial
Body	Neck and forelimbs	C1–T2	Particularly asymmetry Only flexor reflex useful Hopping	All reflexes Hyperreflexia normal Crossed extension normal
	Trunk and hindlimbs	T3–S2 L4—femoral n. L5—cranial gluteal n. L6–S1—sciatic n.	Particularly asymmetry Patellar reflexes usefulFlexor reflex useful	All reflexes Hyperreflexia Crossed extensor reflex Extensor thrust response
	Tail	Ca1+	Extension and flexion
	Perineum, anus, rectum, and bladder	S1–5	S1–2 is common fracture site
Gait and posture	ORTHOPEDIC PROBLEMS!	Neuromusculoskeletal	VIDEO! Shoulder and hip atrophy common Possible analgesic trial	SEPSIS!
	Positional CP deficits	Brainstem, spinal cord, and sensory nerves	Manual placement of feet/limbs noncontributory	Prematurity
	Extensor weakness	Brainstem, spinal cord, and PNS	Especially final motor neuron lesion	Extensor strength dominant
	Flexor weakness	Brainstem, spinal cord, and PNS
	Ataxia	Spinal ataxia	Irregular position and placement
		Cerebellar ataxia	Hypermetria characteristic; F > H	Normal to degree
		Vestibular gait	Crouched posture Deliberate (predictable) stepping Wide‐based, staggering gait	Normal to degree

      CP, conscious proprioception; CN, cranial nerve.

Head

For the routine large animal patient examination, evaluate what one can from a distance, preferably before the patient is disturbed, for the first observations of behavior, mentation and head, neck, trunk, and limbs. Head and neck deviations need to be assessed closely by straightening the neck along the midline to determine what neck and head asymmetry may be present. Allow the patient to smell an (often peppermint‐tainted) hand for introduction and observe the face, particularly eyes and associated structures, for an expressional response. Then, examine the parts of the head and neck for the evaluation of cranial nerve function (Table 2.3).

Table 2.3 Assessment of cranial nerve function

Cranial nerve	Major function	Normal reflex/response/assessment
I	Olfactory		Sense of smell	Challenging—most odors also stimulate CNV
II	Optic		Afferent pathway for vision and light	Menace response. Pupillary light reflex. Swinging light test Dazzle response
III	Oculomotor		Pupillary constriction Upper eyelid levator muscle Extraocular muscles	Pupillary light reflex Induced eyeball movement Medial movement of globe Ptosis rarely apparent
IV	Trochlear		Extraocular muscle (dorsal oblique)	Ventrolateral rotation of globe
V	Trigeminal Sensory	Sensory to head, face, and tongue	Ear, eyelid, and lip (facial) reflexes Pain perception: head, nasal septum, and rostral tongue
		Motor	Motor to muscles of mastication	Chewing, jaw tone, and muscle mass (temporalis, masseter, and pterygoid)
VI	Abducens		Extraocular muscle (retractor oculi) Extraocular muscle (lateral