Neurological examination in ruminants

Question 1

Mentation, behaviour and sensation assessment

Answer 1

• general exam/whole animal
• can be assessed in all ruminant species but care with large ruminants if show aggressive behaviours

Question 2

What can you assess by looking at the head/neck?

Answer 2

• head position and coordination in all ruminants

Question 3

What can you assess by looking at the limbs?

Answer 3

• limb position and co-ordination
• gait analysis
• muscle tone

Question 4

What can you assess by looking at the trunk?

Answer 4

• body position
• panniculus (cutaneous trunci) reflex

Question 5

What can you assess by looking at the head/face?

Answer 5

• cranial nerve reflexes

Question 6

What can you assess by looking at the tail/perineum/anus?

Answer 6

• tail tone (more tricky in docked sheep)
• perineal and anal reflexes

Question 7

Proprioceptive assessment in ruminants

Answer 7

• conscious proprioceptive positioning (knuckling test): sheep, goats, calves
• wheelbarrow: sheep, goats, calves, care with rumen pressure on diaphragm when in wheelbarrow position
• gait analysis: all spp, ask animal to turn as well as walk in a straight line and assess if limbs excessively abducted/adducted or cross over when turns, assess if limbs drag or excessively lifted (hyper-metric), assess joint movement during walking
• standing position: all spp, wide based or narrow based (both abnormal)
• hoof inspection: all spp, worn hooves suggest dragging/knuckling

Question 8

Spinal reflexes that can be performed in ruminants

Answer 8

• flexor reflex: sheep, goats, young calves, adult cows + big calves when recumbent only
• patellar reflex: sheep, goats, young calves, adult cows + big calves when recumbent only, in newborn ruminants this reflex is hyperactive
• perineal reflex: all spp

Question 9

How to test flexor reflex (forelimb and hindlimb)

Answer 9

• stimulate distal forelimb and observe for flexion of joints (i.e. attempts to withdraw limb from stimulus) +/- conscious perception of stimulus

Question 10

How to test patellar reflex

Answer 10

• place animal in lateral recumbency
• tap patellar ligament of uppermost limb with a large patellar hammer or similar
• observe for stifle extension

Question 11

How to test perineal reflex

Answer 11

• gently prick/pinch the perineal skin and observe contraction of anus and downward movement of tail

Question 12

Approach to farm animal neuro case

Answer 12

1. history and CE: assess primary or secondary, localisation of lesion narrows ddx list
2. further diagnostics to confirm suspected diagnosis: bloods (biochem), CSF tap, PM
3. tx: often based on presumptive diagnosis, may confirm/rule to diagnosis (tx trial)

Question 13

Neuro exam

Answer 13

1. assess mental status (differentiate intracranial lesions from extra cranial lesions)
2. assess cranial nerves
3. assess gait and posture
4. assess postural reactions as far as possible
5. assess spinal reflexes as much as possible
6. assess responses to pain

Question 14

Abnormalities found in which parts of the neuro exam point to intracranial lesions?

Answer 14

• mental status
• cranial nerves
• gait and posture
• postural reactions
• spinal reflexes

Question 15

Abnormalities found in which parts of the neuro exam point to peripheral lesions?

Answer 15

• posture reactions
• spinal reflexes
• responses to pain

Question 16

Is the dz of primary or secondary origin

Answer 16

• primary: conditions directly affecting the neuro system (e.g. brain abscesses, spinal cord injuries)
• secondary: conditions that present with neurological signs but aren’t of neurological origin (e.g. hypomagnesaemia, twin lamb dz)

Question 17

Is the lesion rostral or caudal to the foramen magnum?

Answer 17

• i.e. is the brain affected or not?
• foramen magnum = big hole in back of the head where the spinal cord comes out

Question 18

When the whole body is affected with abnormal mentation, is the lesion rostral or caudal to the foramen magnum, and what structure is likely to be affected?

Answer 18

• rostral
• cerebrum (forebrain)

Question 19

When the whole body is affected with normal mentation, is the lesion rostral or caudal to the foramen magnum, and what structure is likely to be affected?

Answer 19

• rostral
• cerebellum

Question 20

When only the face/head is affected and mentation is normal, is the lesion rostral or caudal to the foramen magnum, and what structure is likely to be affected?

Answer 20

• rostral
• cranial nerves

Question 21

When only the face/head is affected and mentation is abnormal, is the lesion rostral or caudal to the foramen magnum, and what structure is likely to be affected?

Answer 21

• rostral
• brainstem (if depressed mentation)

Question 22

When all 4 limbs are affected and the head/face/mentation is normal, is the lesion rostral or caudal to the foramen magnum, and what structure is likely to be affected?

Answer 22

• caudal
• cervical and cranial thoracic spinal cord (C1-T2)

Question 23

When only the hindlimbs are affected, is the lesion rostral or caudal to the foramen magnum, and what structure is likely to be affected?

Answer 23

• caudal
• thoracolumbar spinal cord (T3-L6)

Question 24

When only the tail/perineum is affected, is the lesion rostral or caudal to the foramen magnum, and what structure is likely to be affected?

Answer 24

• caudal
• sacrococcygeal spinal cord (S1-S3)

Question 25

Localisation of peripheral lesions

Answer 25

- abnormalities of peripheral nerve branches result in presentations opposing to the nerves motor function that affect innervated muscle -- if flexor muscles are innervated, injury will present as hyperextension -- if extensor muscles are innervated, injury will present as flexion - if the affected branch is sensory, sensation of the innervated area will also be affected - can still locate the lesion to the main spinal nerve (from which the nerve has branched)

Question 26

Obturator nerve paralysis

Answer 26

- both hindlimb abducted (away from body) as adductor muscle tone is not balanced with adductor muscle tone to 'hold' hindlimbs in normal position under body -> innervation to adductors is obturator nerve (originates from L5-6)

Question 27

Biochemistry & haematology

Answer 27

- little value in most primary neuro conditions - can be of use if secondary neurological conditions suspected -- Mg (important for mentation) -- Ca (important for mentation) -- Na (important for mentation) -- acid-base balance (can cause mentation problems, e.g. dullness esp in calves) -- specific assays (e.g. toxins)

Question 28

CSF

Answer 28

- rarely diagnostic on its own but does aid diagnosis - obtain from midpoint of lumbosacral space (cattle/goats = L6, sheep L6/7) - depression on midline between last palpable lumbar and 1st palpable sacral vertebrae - standing animal (if recumbent place in sternal with hindlimbs forward) - adult cattle = 4" spinal needle - calves & adult small ruminants = 2" hypodermic needle - lambs & kids = 1" hypodermic needle - clip & surgical prep - LA = bled of procaine - sedate if needed - collect 1-3ml of CSF (carefully draw back syringe to minimise trauma) - collect EDTA sample and plain sample - can get CSF from atlanto-axial joint but needs GA as if moves will accidentally pith animal - culture: send to external lab, listeria typically difficult to culture, septic meningitis typically cultures well

Question 29

Clear colourless CSF

Answer 29

- normal/healthy

Question 30

Turbid CSF

Answer 30

- increased cell count

Question 31

Red-tinged CSF

Answer 31

- bleeding - likely due to contaminated at sampling - can be due to bleeding into CNS

Question 32

Yellow CSF

Answer 32

- release of pigments following rbc lysis in CNS -> occurs 2-6h after bleeding and lasts up to 10d

Question 33

Imaging

Answer 33

- rarely done not for research purposes