Neuro exam of LA (Equine)

Question 1

Why is it important to perform a good PE before doing a neurological exam?

Answer 1

Other reasons for the problems:

• Non- neurological reason for weakness (lameness)
• In horses, liver disease causes neuro signs - depressed (hepatic encephalopathy)
• Asymmetric pelvic limb problem - foot abscess?

Question 2

What does hyperaesthesia mean?

Answer 2

Hypersensitivity to environment

Question 3

What are the signs for cerebellar disease in a horse? Common?

Answer 3

• BAR
• Exaggerated/spastic movement
• absence or diminished menace reflex
• intention tremor (head shake just before doing something)
• Ataxia without weakness
• Eye and lip tremors
• Involuntary defecation

Uncommon in horses

Question 4

What are the signs indicative of brainstem lesions (pons and medulla) ?

Answer 4

CN defects (depending on location - affect more than one)
Ataxia
Paresis (present together)
(shuffling)

Question 5

What signs indicate trigminal nerve paralysis in the horse?

Answer 5

Atrophy of masticatory muscles (masseter) and loss of sensation on affected side

Question 6

In acute paralysis of the facial nerve, how can you tell what side the lesion is on?

Answer 6

Muscles of the face deviate away from the lesion, and ear droop occurs on side of lesion

Facial nerve usually affected with vestibular nerve - close location

Question 7

How can you distinguish between central and peripheral vestibular disease in the horse?

Answer 7

• Vertical orientation of nystagmus indicates a central problem (Brain and SC)
• Central lesions also often involve other cranial nerves (8,9,10)
• Fast phase - the way it moves - lesion on the other side?
• Horizontal orientation of nystagmus indicates a peripheral problem (CN and out of B/BS)

Question 8

What is ataxia?

Answer 8

A functional deficit associated with defective proprioception - presented as hypermetria, hypometria, dysmetria, trunchal sway

Question 9

What are the major causes of ataxia in a horse?

Answer 9

1. Cerebellar dysfunction
2. Vestibular dysfunction
3. Spinal cord lesions
4. Peripheral nerve

Question 10

What different functions do LOWER MOTOR NEURONS have compared to UPPER MOTOR NEURONS?

Answer 10

UMN- control muscles

LMN- contract muscles - actively synapsing in m

Question 11

What are the CS when there is: a problem with:

a) UMN
b) LMN

Answer 11

a) Inability to control muscles, normal or increased tone, no muscle atrophy
b) Inability to contract the muscles, flaccidity, muscle atrophy if chronic

Question 12

How are ataxia and lameness different?

Answer 12

A - associated with irregular irregularities

L- regularly irregular

Question 13

How would you localise spinal lesions?

Answer 13

• Limb weakness indicates spinal cord damage
• hard to access spinal reflexes in adult horse
• animal movements indicate site of lesion

Question 14

What can you access if there are problems with the sacral and perineal regions?

Answer 14

• Perineal reflex
• Sensation
• tail flaccidity
• rectal exam
• urinary incontinence

Question 15

What issues can you see if forebrain in a horse is affected?

Answer 15

• circling
• hyperaesthesia - v active
• head turn
• odd postures

Question 16

What cs can be seen in the reticular formation in the BS is affected?

Answer 16

• Depressed

- Blinking constantly

Question 17

What are the nerves that control the retractor oculi reflex?

Answer 17

• Press on cornea through eyelid - feel the reflex retraction of the globe
• Afferent: Trigeminal nerve (V)
• Efferent: Abducens nerve (VI) - Retractor muscle