Large Animal Neurology Examination

Question 1

What clinical signs would you expect to see in a Horse with a forebrain lesion?

Answer 1

yawning, head pressing, circling, hyperaesthesia, odd posture

Question 2

What clinical signs would you expect to see in a Horse with a cerebellum lesion?

Answer 2

spastic/ exaggerated movements, absent or diminished menace, intention tremors, ataxia without weakness (just the wobbling)

Question 3

What structures should be considered to be involved when looking at Brainstem lesions?

Answer 3

ascending proprioceptive pathway (think weakness and ataxia)
descending motor pathways (think weakness and ataxia)
cranial nerve nuclei

Question 4

What nerves are tested in the pupillary light reflex?

Answer 4

Optic Nerve (afferent limb)
Oculomotor Nerve (efferent parasympathetic fibres)

Question 5

What structures are involved in the Menace House? (5)

Answer 5

Optic Nerve, Optic Chiasm, Thalamus, Opposite Occipital cortex, Facial Nerve

Question 6

What is the best way to examine vision in a Horse? (2)

Answer 6

‘Obstacle Course’- cover one eye and walk horse around and between obstacles
Also perform a fundic exam

Question 7

What nerves control the position of the eye?

Answer 7

Oculomotor Nerve (III)
Trochlear Nerve (IV)
Abducens Nerve (VI)

Question 8

What is the Retractor Oculi Reflex?

Answer 8

press on cornea through the eyelid and feel for the reflex retraction of the globe

Question 9

What nerves are tested in the Retractor Oculi Reflex?

Answer 9

Trigeminal Nerve (V)- afferent
Abducens Nerve (VI)- efferent

Question 10

What clinical signs are associated with trigeminal nerve damage?

Answer 10

Muscle atrophy
Loss of sensation on the face

Question 11

What is the main clinical sign associated with Vestibular (VIII) ear damage?

Answer 11

Ear drooping

Question 12

What does Nystagmus suggest about the location of the lesion?

Answer 12

Likely to be a lesion in the peripheral nuclei of the brainstem

Question 13

Lesions in the IX (glossopharyngeal) or X (vagus) nerve present as…
How are they diagnosed?

Answer 13

Issues swallowing or Vocalising
Diagnosed with Endoscopy

Question 14

What is Horner’s syndrome caused by?

Answer 14

Caused by an interruption of the sympathetic nerve pathway between the hypothalamus and the eye

Question 15

Briefly describe the sympathetic nerve supply pathway for the skin and eyes?

Answer 15

Sensory nerves are innervated > Travel through the spinal chord to 2nd order neuron > leaves via brachial plexus to travel to the vagosympathetic trunk where the tertiary axons innervate the eyes and skin

Question 16

What is the difference between Hyper/ Hypo and Dysmetria?

Answer 16

Hyper- increased movement
Hypo- decreased movement
Dys- both increased and decreased movement e.g. no movement then all at once

Question 17

How do we differentiate pelvic limb lameness from ataxia?

Answer 17

Lameness tends to be regularly irregular
Ataxia is generally irregularly irregular

Question 18

How do we differentiate upper vs lower motor neuron weakness?

Answer 18

Upper- inability to control the muscles, increased tone, exaggerated movements
Lower- inability to contract the muscles, flaccidity and muscle atrophy

Question 19

How would we diagnose lameness caused by muscle disease?

Answer 19

will present post exercise- measure CK and AST in the blood- Creatine kinase (CK) and Aspartate aminotransferase indicate muscle damage

Question 20

What are some common signs of a Lower Spinal Lesion in Horses?

Answer 20

Tail flaccidity
‘itchy’ back end
Urinary incontinence