Equine Neurology Exam

Mental awareness is typically controlled by what?

Higher centers of the brain like the cerebral cortex and the Ascending reticular activating system (ARS)

What are signs mental awareness is being affected?

Dullness

Lethargy

Obtundation

Stupor

Coma

What is initiated at the cerebral cortex?

Voluntary movement

What is the most common location damaged w/ progressive stupor?

Thalamus

Where is the ARAS located?

Throughout medulla, midbrane and thalamus

What are signs of vestibular dz?

Strabismus

Head tilt

Nystagmus

A head tilt will point ___ the lesion and a nystagmus will move ___ from the lesion?

Toward

Away

What is Schiff-Sherrington syndrome?

Forelimb extensor rigidity w/out opisthotonus

Where is the lesion in Schiff-Sherrington syndrome?

Thoracolumbar spinal cord

What is opisthotonus?

Head and neck are hyperextended

With ____ opisthotonus all for limbs will have extensor rigidity

With ____ opisthotonus only forelimbs will have extensor rigidity and intention tremors

Midbrain

Cerebellar dz

What are signs of spinal ataxia?

Base wide stance

Knuckling

Sway

Dog tracking

Localize the lesion:

Mentation change

Cerebral

Localize the lesion:

Intention tremors

Cerebellar

Localize the lesion:

Ataxia in hind limbs

Thoracolumbar/ sacral spine

Localize the lesion:

Ataxia in both Front and hid limbs affected

Cervical spine

Localize the lesion:

Ataxia worse in Front limbs, but present in hind limbs

Thoracic intumescence

Localize the lesion:

Both vision and PLR (pupillary light reflex) abnormal

Optic nerve

Localize the lesion:

Vision abnormal, PLR normal

Cortical lesions

Localize the lesion:

PLR abnormal, vision normal

Efferent arms lesion

Localize the lesion:

Horners syndrome

Sympathetic innervation to the eye

What are symptoms of horners syndrome?

Pitosis

Miosis

Enophthalmosis (globe withdraw)

Protrusion of 3rd eyelid

Sweating on ipsilateral side

Localize the lesion:

Horners syndrome resulting in sweating of face and cranial neck to C2

Guttural pouch/ cranial cervical ganglion

Localize the lesion:

Horners syndrome resulting in sweating of neck to C3-4

Sympathetic trunk

Localize the lesion:

Horners syndrome resulting in sweating down to the shoulder T1

Thoracic inlet lesion

What is Anisocoria?

unequal pupil size

Localize the lesion after horse was left in dark room and exposed to dim light:

Pupils dilate to equal size

Initially dilated pupil is affected due to CN III lesion

Localize the lesion after horse was left in dark room and exposed to dim light:

Pupils do not dilate equally

Smaller pupil affected - sympathetic innervation abnormal - horners syndrome

Hyperreflexia is ____ motor neuron issue, Hyporeflexia is ____ motoneuron issue

Upper

Lower

Localize the lesion:

Panniculus/ cutaneous trunci is negative

Lesion is anywhere cranial to test

What do we use cervicofacial reflex to test?

Local spinal or facial nerve deficit

What do we use Lordosis and Kyphosis responses to test?

Musculoskeletal pain in back/ hips

Loss of balance/ trouble extending

Localize the lesion:

Perianal and anal tone reflexes were negative?

Cauda equine/ sacral dz

A horse with spinal ataxia will look more normal when traveling ____?

Faster

A horse w/ hypermetra will have excessive ___ of a limb?

Lifting

A horse w/ hypometra will have ___ and ____ of a limb

Weakness

Dragging

How can you test an intention tremor?

Feeding a horse

Grade the ataxia:

Mildly affected, need multiple tests to see, likely wont go to olympics

Grade 1

Grade the ataxia:

Mildly affected, Appreciated by professional, performance limiting

Grade 2

Grade the ataxia:

Obvious to layperson, notable at rest

Grade 3

Grade the ataxia:

Severely ataxic, could fall during exam

Grade 4

Grade the ataxia:

Recumbent, unable to stand

Grade 5

What are we looking for when walking a horse in circles/ tight circles?

Pivoting,

Circumduction

Low/ high foot flight

Toe dragging

What is a normal cadence of a horse cantering in a circle?

3 Beat gait

What might a neurologic horse do when cantering in a circle?

Bunny hop

Cross canter

Why do we perform a tail pull?

Tests extensor reflex and could show a Lower motor lesion at L3-L5

What does walking w/ head elevated test for?

Removes visual compensation - abnormal if cat walking

What do obstacles do in a neuro exam?

Measure functional proprioception