Clinical Neurology Approach to the Horse Flashcards

1
Q

How is a Differential Diagnosis list made?

A
D: Degenerative/ Developmental
A: Anomalous/ Autoimmune/ Anatomic
M: Metabolic/ Mechanical
N: Nutritional/ Neoplastic
I: Inflammatory/ Infectious/ Inherited/ Immune-mediated/ Iatrogenic/ Idiopathic
T: Trauma/ Toxic
V: Vascular
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2
Q

What are the most common differentials from DAMNITV in the young and old horse?

A
  • Young:
    Developmental/ Inherited, Infection/ Infestation, Neoplastic (Lymphoma)
  • Old:
    Degenerative, Neoplastic
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3
Q

What disease(s) are Thoroughbred horses predisposed to?

A
  • Cervical vertebral stenotic myelopathy (CVM 1 = Dynamic form)
  • Mainly in 6 months to 3 years in rapidly growing colts
  • This form is more common in younger horses. Spinal cord compression is caused by excessive movement of the vertebrae during flexion and extension of the neck and is therefore dynamic in nature. Vertebrae C3-C5 are most commonly affected.
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4
Q

What disease(s) are Sport horses predisposed to?

A
  • Cervical vertebral stenotic myelopathy (CVM 2 = Static Form)
  • This form is more common in older horses, as a result of osseous change in the vertebrae. The spinal cord is constantly compressed. Vertebrae C5-C7 are most commonly affected.
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5
Q

What disease(s) are Arabian horses predisposed to?

A
  • Epilepsy

- Atlanto-Occipital malformation

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6
Q

What disease(s) are Appaloosa horses predisposed to?

A
  • Blindness
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7
Q

What disease(s) are Quarter horses predisposed to?

A
  • Hyperkalemic Periodic Paralysis (HYPP)
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8
Q

What are the 2 main reasons to a change in behaviour and mentation in a horse?

A

1) Lesion in the brain/ spinal cord (Focal vs Diffuse)

2) Metabolic lesion that affects the brain/ spinal cord

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9
Q

What kind of lesion are the following clinical signs associated with?
Animal turns, leans, holds head and circles to the affected side, with a reluctance to turn to the other side

A

A Focal Lesion of the Brain

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10
Q

What kind of lesion are the following clinical signs associated with?
Excitement, restlessness, aggression, compulsive walking and circling, progressive depression, head pressing, apparent pruiritus (biting at itself), blindness

A

A Diffuse Lesion of the Brain

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11
Q

What kind of lesion are the following clinical signs associated with?
Mild to profound depression, cranial nerve deficits, apnea and non-responsive mydriasis

A

A Brainstem Lesion

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12
Q

What other body systems of the horse might be involved or exhibit similarly to a neurological disorder?

A
  • Liver
  • Kidney
  • Musculo-skeletal
  • Gastrointestinal
  • Systemic disease
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13
Q

Which reflex and cranial nerves are we assessing by doing a Menance test?

A
  • Palpebral reflex
  • Cervico-facial reflex

CN’s 2, 5 (trigeminal), 7 (facial) and 11

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14
Q

Which cranial nerve are we assessing by doing a Tongue Tone test?

A

CN 12

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15
Q

Which cranial nerve are we assessing by looking for facial symmetry?

A

CN 7 (facial)

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16
Q

What CN deficit do the following signs suggest?

ear droop, ptosis, decreased menance, deviated muzzle

A

CN 7 deficit

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17
Q

Which cranial nerve are we assessing by testing to see if the horse can chew?

A

CN 5 (trigeminal)

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18
Q

What CN deficit do the following signs suggest?

head tilt

A

CN 8 (vestibular)

19
Q

What CN deficit do the following signs suggest?

head tilt to side of lesion, horizontal nystagmus with quick phase away from lesion, loss of exterior tone ipsilaterally

A
CN 8 (vestibular)
Specifically a Peripheral Vestibular Disease (as opposed to Central Vestibular Disease)

note: horses often have concurrent 7 & 8 damage

20
Q

What CN deficit do the following signs suggest?

depression, deficits of other cranial nerves, ataxia/ paresis/ proprioceptive deficits, vertical/ positional nystagmus

A
CN 8 (vestibular)
Specifically a Central Vestibular Disease (as opposed to Peripheral Vestibular Disease)

note: ataxia/ paresis/ proprioceptive deficits suggest injury to the tracts in the brainstem

21
Q

Which cranial nerves are we assessing when we do an ophthalmologic exam?

A

CN 2, 3, 4, 5, 6, 7 & 8

22
Q

Which cranial nerves are we assessing when we do a Pupillary Light Reflex on the eye?

A

CN 2 & 3

note: it does not test vision quality, just if the eye is receptive to light or not
note: tests ipsilateral 2 and 3, and contralateral 3 = when light shines in one eye, both should constrict, but the ipsilateral side should constrict MORE

23
Q

Which cranial nerves are we assessing when we do a Dazzle reflex test?

A

CN 2 & 8

24
Q

Define ‘Strabismus’

A

Strabismus is a condition in which the eyes do not properly align with each other when looking at an object

25
Q

Which CN is responsible for the following eye muscles: Dorsal, ventral, medial rectus & ventral oblique?

A

CN 3 (oculomotor)

26
Q

Which CN is responsible for the following eye muscles: dorsal oblique?

A

CN 4 (trochlear)

27
Q

Which CN is responsible for the following eye muscles: lateral rectus?

A

CN 6 (abducens)

28
Q

Define ‘Weakness’/ ‘Paresis’

A

Wekness or Paresis is a deficit of motor function

29
Q

Where in the nervous system can a lesion be found when dealing with Weakness/ Paresis?

A
  • Brain
  • Brainstem
  • Upper Motor Neuron
  • Lower Motor Neuron
  • Motor end plate
  • Muscle
30
Q

Define ‘Proprioception’

A

Proprioception is a sense of position in space, it can be divided into conscious and unconscious proprioception

31
Q

Define ‘Ataxia’

A

Ataxia is an unsteady and swaying walk, often with feet planted widely apart. Animals have difficulty walking a straight line

32
Q

Define ‘Dysmetria’

A

Dysmetria is a lack of coordination of movement typified by the undershoot or overshoot of intended position with the limb. It is a type of ataxia. It can also include an inability to judge distance or scale.
Controlled by the Cerebellum

33
Q

What kind of posture deficit is suggestive from the following clinical signs: wide base stance and proprioceptive deficits in foot placement?

A

Ataxia

34
Q

What kind of posture deficit is suggestive from the following clinical signs: weight shifting, less muscle tone/ muscle fasciculation and decreased reflexes?

A

Lower Motor Neuron Weakness

35
Q

How can we test Lower Motor Neuron Weakness?

A
  • Pull on withers and tail standing and at walk
  • Lift feet
  • Panniculus reflex
  • Anal/ Perianal reflex
  • Gait deficits
36
Q

How can we test for Ataxia?

A

Placement/ Proprioception tests:

  • Place forelimb in front of the other
  • Lift and pull hindlimb

Gait deficits

37
Q

On the gait examination, what do the following clinical signs suggest: Hypermetria, truncal sway, failure to lift leg, dragging toes, swumbling, reluctance to back up?

A

Weakness

38
Q

On the gait examination, what do the following clinical signs suggest: inconsistent placement of limbs, circumduction, stepping on own feet, pivoting, swaying?

A

Ataxia

39
Q

What part of the nervous system is affected based on the following clinical signs: ataxia, intention tremor and dysmetria?

A

Cerebellum

40
Q

What is the clear difference between ataxia and weakness?

A

Ataxia affects coordination but NOT strength

Weakness affects ONLY strength

41
Q

Once a dysfunction has been identified it has to be graded on a 1-5 scale, describe this grading system

A
  • Grade 1: subtle, barely perceptible
  • Grade 2: subtle, but clearly present
  • Grade 3: obvious deficits
  • Grade 4: very unstable
  • Grade 5: recumbent
42
Q

How can a neurological lesion be localized to a specific point?

A

Work through flowchart on laptop

43
Q

What further diagnostics (beyond the physical exam and neuro exam) can be used to localize a specific neurological lesion

A
  • CBC/ Serum biochemistry
  • Imaging: radiographs, CT/MRI
  • CSF analysis
  • Serology
  • Vit E/ Se-GTP levels