Equine Neurology

Question 1

How do we assess the olfactory n in a horse?

Answer 1

CN I
Detection of hidden treat

Question 2

How do we assess the optic n in a horse?

Answer 2

CN II
Menace response, PLR, dazzle reflex

Question 3

How do we assess the oculomotor n in a horse?

Answer 3

CN III
PLR, eye position, medial movement

Question 4

How do we assess the trochlear n in a horse?

Answer 4

CN IV
Eye position, ventrolateral

Question 5

How do we assess the trigeminal n in a horse?

Answer 5

CN V
Cutaneous sensation, tone of masticatory muscles, ability to chew

Question 6

How do we assess the abducens n in a horse?

Answer 6

CN VI
Eye position, retraction, lateral movement

Question 7

How do we assess the facial n in a horse?

Answer 7

CN VII
Facial symmetry, rostral tongue sensation

Question 8

How do we assess the vestibulocochlear n in a horse?

Answer 8

VIII
Head tilt/turn, circling/leaning, response to environmental sounds

Question 9

How do we assess the glossopharyngeal n in a horse?

Answer 9

CN IX
Ability to swallow

Question 10

How do we assess the vagus n in a horse?

Answer 10

CN X
Laryngeal abduction (“slap test”)

Question 11

How do we assess the accessory n in a horse?

Answer 11

CN XI
Cranial neck muscle symmetry

Question 12

How do we assess the hypoglossal n in a horse?

Answer 12

CN XII
Tongue tone

Question 13

What are signs of paresis?

Answer 13

Toe dragging
Knuckling
Stumbling
Inability to resist tail pull

Question 14

What are the predominant clinical signs associated with the cerebral cortex?

Answer 14

Postural deficits
Seizures
Altered mentation
Blindness

Question 15

What are the predominant clinical signs associated with the brainstem?

Answer 15

Ataxia
Weakness and dysmetria
Mild to moderate dysphagia
Anisocoria or dilated pupils

Question 16

What are the predominant clinical signs associated with the vestibular system?

Answer 16

Ataxia
Head tilt
Postural deficits

Question 17

What are the predominant clinical signs associated with the cerebellum?

Answer 17

Ataxia and intention tremors

Question 18

What are the predominant clinical signs associated with UMNs in the spinal cord?

Answer 18

Paresis
Ataxia
Dysmetria

Question 19

What are the predominant clinical signs associated with LMNs in the peripheral nerves?

Answer 19

Weakness
Postural deficits and ataxia

Question 20

What are the predominant clinical signs associated with C1 - C5?

Answer 20

Question 21

What are the predominant clinical signs associated with C6 - T2?

Answer 21

Question 22

What are the predominant clinical signs associated with T3 - L3?

Answer 22

Question 23

What are the predominant clinical signs associated with S3 - S5?

Answer 23

Question 24

What are the predominant clinical signs associated with coccygeal?

Answer 24

Question 25

Which cranial nerves are located within the guttural pouch?

Answer 25

V, VII, VIII, IX, X

Question 26

What are the 3 most common differential diagnoses for any horse with spinal ataxia?

Answer 26

Cervical vertebral compressive myelopathy (CVCM) - "wobbler" Equine protozoal myeloencephalitis (EPM) Equine degenerative myelopathy/equine neuronal dystrophy (EDM/eND)

Question 27

What clinical signs are associated with CVCM?

Answer 27

Symmetrical ataxia, dysmetria, paresis in all 4 limbs Normal mentation, intact peripheral nerve function

Question 28

What is the treatment for CVCM?

Answer 28

Caloric restriction in growing horses (<2y of age) Cervical vertebral interbody fusion surgery

Question 29

What is the etiologic agent of EPM? What are important hosts?

Answer 29

Sarcocystis neurona, Neospora hughesi *Progressive, multifocal* Definitive host: opossum Intermediate hosts: racoons, skunk

Question 30

What are the clinical signs of EPM?

Answer 30

Spinal cord: asymmetry (!!!), muscle atrophy, ataxia, dysmetria, paresis Brainstem: CN VII, VIII, seizures, lethargy

Question 31

How is EPM diagnosed?

Answer 31

SAG2, 4/3 ELISA Confirm intrathecal antibody production via **serum:CSF titer ratio**

Question 32

How is EPM treated?

Answer 32

Ponazuril (1st line)

Question 33

What is the pathophysiology of EDM/eNAD?

Answer 33

Predisposition to vitamin E deficiency Onset of 1-12m of age

Question 34

What clinical signs are associated with EDM/eNAD?

Answer 34

Symmetric ataxia, proprioceptive deficits (decreased menace, lethargy, behavior change)

Question 35

How is EDM diagnosed?

Answer 35

Exclusion Low serum vitamin E

Question 36

How is EDM treated?

Answer 36

Vitamin E supplementation

Question 37

Answer 37

Radial n paralysis Non-weightbearing Dropped elbow Inability to advance limb

Question 38

Answer 38

Femoral n paralysis Non-weightbearing Flexion of stifle, hock, fetlock Less of sensation medial aspect of limb

Question 39

Answer 39

Suprascapular n paralysis "Sweeney" Muscle atrophy Abnormal gait with shoulder exo-rotation Trauma to nerve at point of the shoulder

Question 40

What are the core vaccines for horses?

Answer 40

Rabies Tetanus Eastern Equine Encephalomyelitis Western Equine Encephalomyelitis West Nile Virus Encephalomyelitis

Question 41

What are the clinical signs of rabies in horses?

Answer 41

Ataxia and paresis Lameness Recumbency Pharyngeal paralysis Colic *Fatal encephalopathy in 5-7 days*

Question 42

What are the clinical signs of tetanus in horses?

Answer 42

Question 43

What are the clinical signs of EEE/WEE/WNV?

Answer 43

EEE/WEE: inapparent infection with fever ~2d after infection WNV: 10% develop signs, incubation 9-11d Generalized febrile illness

Question 45

How is EEE/WEE/WNV diagnosed?

Answer 45

IgM capture ELISA IgM elevated for 4-6 weeks

Question 46

What clinical signs are associated with equine herpesvirus myeloencephalopathy?

Answer 46

Asymmetric ataxia, dysmetria, paresis *Ascending myelopathy = dog-sitting, loss of tail tone, incontinence*