Lecture 22: Equine Neurologic Examination

What are the 5 components used in an equine neuro exam?

1.Sensorium and mental attitude

2.Gait and posture

3.Postural reactions

4.Muscle tone & size, spinal reflexes

5.Cranial nerves

What is examined in the head region on a neuro exam?

What are signs of decreased alertness?

Lethargy: blank facial expression, drooping ears and eyelid, sluggish responsiveness to stimuli, reduced voluntary activity

Stupor: stands in one place, head held low, only responds to strong stimuli

Coma: semi-comatose = recumbent, responds; comatose = recumbent, unresponsive

What behaviors are you looking for on a neuro exam?

•Self-mutilation

•Head pressing

•Compulsive walking

•Yawning

•Head pressing

•Aggression

•Timidity

•Loss of affection

What postures are you looking for on a neuro exam?

•Wide/narrow based stance

•Tilt (peripheral vestibular  = towards)

•Turn/circling (central = towards)

•Leaning

•Recumbency

•Opisthotonos

What are the 12 CN and what are their major functions?

How do you assess the first 6 CN?

1. olfactory → difficult to assess

2. optic → menace, PLR

3. oculomotor → PLR, medial movement globe

4. trochlear → ventrolateral rotation globe

5. trigeminal → sensory: ear, eyelid, lip (facial) reflexes and pain/perception; motor: chewing, jaw tone, muscle mass

6. abducens → eyeball retraction (corneal reflex), lateral movement globe

How do you assess the last 6 CN?

7. facial → ear, eyelid, lip (facial) tone, reflexes, movements, symmetry

8. vestibular/cochlear → head posture, induced eyeball movement, normal gait, blind fold test, response to noise, normal vestibular nystagmus

9. glossopharyngeal → swallowing (observation, palpation), endoscopy, slap test

10. vagus → ““

11. accessory → ““

12. hypoglossal → tongue size and symmetry

How is equine vision evaluated?

•Menace (temporal, nasal field)

•Vision in unfamiliar environment and different light

•Fundus exam

How are equine eyes evaluated for straismus, nystagmus, pupillary size, and pain?

•Move head up/down

•Move head side to side

•Eye position, strabismus

•PLR: Direct, Swinging light

•Look at angle upper eye lashes

How is the trigeminal nerve tested?

• observe facial symmetry

• test facial sensation

• if motor issue → atrophy of temporalis, masseter, pterygoid mm.

What are the signs of facial nerve issues?

issues with muscle of facial expression and motor issues

• ear droopy

• upper eyelid droopy

• upper lip deviated

• lower lip droopy

How is tongue tone evaluated?

pull tongue through interdental space and see how long it takes for them to pull it back in, repeat on both sides

How do you evaluate the body for neurologic function?

What is the first thing you do on a neuro exam when evaluating the neck and thoracic limbs?

• distance exam with a 360 degree view and compare

• observe → palpate → manipulate

• look for atrophy, asymmetry, trembling, sweating

Where can you palpate C6-C7?

deep in front of shoulder

What reflexes and manipulations are performed on the neck and thoracic limbs during a neuro exam?

Neck flexion (use food)

• “eat food at side of chest”

• Lifts/lowers head/neck adequately

Reflexes

• Slap test

• Cervicofacial reflex

• Cutaneous trunci (panniculus)

Limb strength & sensation, gait, posture

How is the slap test: thoraco laryngeal adductor reflex (TLAR) performed?

• “Hook” highest point of larynx

• Slap wither opposite side

• Feel discrete movement

• Test both sides

gentle slap behind withers triggers ascending pathway of reflex arc → fibers cross over with motor (efferent) pathway to larynx

What are you palpating for in the trunk and pelvic limbs during a neuro exam?

• Back extension

• Back flexion

• Cutaneous trunci

What are you examining on the rectum, bladder, anus, and tail during a neuro exam?

•Anal reflex

•Perineal sensation

•Tail tone

•Signs of incontinence

How are spinal lesions localized based on gait/posture?

What is paresis in clinical neurology?

deficiency to support weight or generate gait

What causes the inability to support weight vs generate gait?

If suspecting paresis, how do you test limb strength?

PALPATION & MANIPULATIOn:

• Hopping (front)

• Tail pull (hind)

• Standing (L3-L5)

• Walking (Cervical)

What are the three types of ataxia?

What are signs of ataxia?

Scuffing, dragging

Delayed protraction, knuckling

Crossing over

Stepping on other foot

Pivoting, circumduction

Elongated stride

What is dysmetria, hypermetria, and hypometria?

• Dysmetria -  lack of coordination of movement (distance, speed, range)

• Hypermetria -  overshoot intended position

• Hypometria -  undershooting intended position

How do you differentiate ataxia from lameness?

• lames horses are regularly irregular (predictable)

• ataxic horses are irregularly irregular (unpredictable)

What are the maneuvers used to test limb strength and gait during a neuro exam?

LIMB STRENGTH

• Tail pull

• Hopping

GAIT

• Walk straight (observe front, back, side)

• Trotting away and towards observer

• Serpentine

• Elevate head

• Blind fold

• Up/down curb

• Circle large, small, both directions

• Backing

• Up and down hill

What does tail pull or sway evaluate for?

• Resistance assesses strength

• Letting go looks at balance

What are the abnormal findings associated with a neurologic horse walking in a small circle?

• Awkwardness

• Pivoting (inside leg held in place)

• Circumduction (outside leg abducts excessively)

• Steps on itself

What are the abnormal findings associated with a neurologic horse backing up?

• Reluctance/refusal

• Dragging feet

• Collapsing

• Dog sitting

How is ataxia graded?

0	Normal strength and coordination
1	Subtle deficits, observed with testing
2	Deficits apparent to inexperienced clinician at walk
3	Deficits noted at rest and walk, may fall with test
4	Severe deficits, may fall spontaneously
5	Recumbent patient

What are the signs of UMN damage vs LMN?

How do you localize the lesion in a recumbent horse?

can lift head → proximal cervical spine

can roll up to sternal → distal cervical spine

can dog sit → > T2

How do you perform a neuro exam in the recumbent horse?