As a Veterinary doctor we may come with the condition horse where they may show various abnormal conditions which is directly linked to their nervous system. This PPT is designed to access the knowledge regarding how to access the neurological state of the horse by performing general steps. By completing the steps mentioned here one can be able to access the neurological condition of Horse.

1. Study Circle
Presented by: Sachin Shrestha
Semester: 5th (Fifth)
Roll no: 37 (Thirty-Seven)
Venue: Paklihawa Campus
Program: B.V.Sc & A.H
Tribhuvan University
Institute of Agriculture and Animal Science
Paklihawa Campus, Rupendehi
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Neurological Evaluation Of Horse

3. Introduction
Horse is a dynamic animal which has been in close relation to human
since ages.
We may encounter unusual behavior of the horse like Limping, Unusual
stance, May show sign of depression or over sensitive to the stimuli
These condition shown by horse can have both orthopedic and
neurologic origin
To distinguish the either orthopedic of neurologic origin we need to
make sure whether the condition shown is ‘Regular Irregularity’ or
‘Irregular Irregularity’
If the signs are irregular then we can assure the horse may have
neurologic problems.
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4. What examiner need to do?
Examiner need to access the condition to make sure whether the
condition is linked to cranial nerves or spinal nerves or may have
vestibular dysfunction
Examiner need to give a thorough look of the horse from head to tail
to avoid overlooking any important lesions
Examiner need to take special attention to patient history, horse’s
mental state, behavior, stance and clinical examination
Spinal nerves are examined by the menace and other reflexes
Incoordination is examined by checking their gait
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5. Methodology
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6. Evaluation of Mental Status
Horse is checked for any encephalopathic behavior such as
Compulsive circling, Head pressing, Cortical/Central blindness,
Seizures or significant change in Mentation.
If there is encephalopathic behavior and there is any unknown
vaccination history of rabies then special caution need to be practiced
Horse need to be accessed for Hyper aesthetic, Depressed or
Lethargic, Stuporous, Obtunded and Comatose
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7. Normal Horse are alert and responsive, although the spectrum
encompasses very calm, placid horses to overly alert, anxious
individuals
Hyperesthestic horses are hyper-responsive to stimuli and often jerk
or tremor when stimulated
Depressed or lethargic horses may have either mild intracranial
disease, systemic disease, or pain. A thorough physical examination is
necessary to tell the difference
Obtunded horses do not respond to normal stimuli (such as a stranger
walking to their stall door or entering the stall) and only respond to
increased stimuli (such as loud noises, sudden movements, or firm
pressure).
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8. Stuporous horses only respond to painful stimuli (such as skin being
squeezed with a hemostat).
Comatose horses do not respond to any stimuli
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9. Examining Cranial Nerves
Testing Eyes by Menace response, Pupilary light reflex, normal eyes
position, Palpebral reflex
Likewise normal facial expression, ability to move their ears, blink
and wiggle lips/muzzle are accessed.
Similarly, Masticatory muscle size and its function, Strength of the
tongue (Ability to retract when pulled) are also accessed.
Eating and drinking behavior are also accessed for their ability to
swallow.
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This horse has a wide-based
stance and it has reduced
awareness due to head trauma.

11. Abnormal position of the
legs may indicate problem
in neck
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12. Unilateral tongue-muscle
atrophy in a horse with
unilateral hypoglossal nerve
damage.
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Mydriasis of horse’s right pupil
compared with the left pupil. These
abnormalities were caused by right-
sided oculomotor nerve damage
subsequent to polyneuritis

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Test Tested nerve Interpretation/abnormal response
Threat reflex Optic (II), Facial (VII) Not blinking the eyes indicates
blindness, should be differentiated
from facial dysfunction
Pupil reflex Optic (II), Oculomotor (III) No constriction of the pupil
Feeling of the
face
Sensory branch facial (VII) No response to stimulation
Facial
symmetry
Motor branch facial (VII) Drooping ear or lip
Eyelid reflex Trigeminal (V), Facial (VII) Blinking the eyes does not work
Nystagmus Oculomotor (III), Vestibular
system
Vestibular disorders (peripheral or
central)
Swallow Glossopharyngeal (IX), Vagus
(X)
Inability to swallow
Tongue tonus Hyoglossus (XII) Tongue is not withdrawn or weak
tone
Table showing the testing of cranial nerves

15. Examining Spinal Nerves
Horses need to be accessed in recumbent position during which
tendon reflex and withdrawal reflex are checked
While in standing position, cerebro-facial reflex, cutaneous trunci, tail
tone, perineal reflex and anal tone are accessed.
Horses are need to be checked for Hypoalgesia (for loss of sensation),
Hyperalgesia(increased sensation), Abnormal sweating(sympathetic
denervation) and salivation
Horses also need to be accessed for any sign of muscle atrophy
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16. Examining Gait and Posture examination
Posture can be evaluated (Head, Neck and Body) while in standing
position
Gait evaluation is done in open space where horse is made to go
through the various tests
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17. Gait Test
❖Slow steps on the straight line
❖Spin horse in tight circles
❖Zig-zag steps
❖Going Backwards
❖Pulling the tail at rest and during movement in each direction
❖Small circles step in both direction
❖Trot on the straight line
❖Different transitions steps- trot
❖Different transitions trot- canter
❖Walking on slope
❖Blindfolding the horse or moving the head up to accentuate the symptoms
❖Walking horse on uneven ground
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Key aspects of an
equine neurological
examination

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Tight circles and the ‘Tail-pull’

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Horse with fairly typical
symptoms of "equine
motor neuron disease". The
horse stands with its belly
raised. Often, they show
muscle tremors and keep
the start in an abnormal
position. The limbs are
placed too far below the
mass.

21. What to expect from the gait test?
These gait test will determine various abnormalities like dysmetry,
incoordination, paresis, specific abnormalities due to nerve failure.
Like the horse may frequently stumble, tug with the toe, kick their
feet and often stride length, difficulty in galloping and cannot canter
for long time
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22. Gradation of the Ataxia
After diagnosis of Ataxia, it is graded on the range of 0-5
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Degree Description
0 No Neurological abnormalities
1 Subtle neurological abnormalities, more pronounced when moving
and turning backwards
2 Mild neurological abnormalities, continuously visible, more
pronounced when backwards and turning
3 Obvious neurological abnormalities with tendency to trip or fall
when turning or moving backwards, abnormal position at rest
4 Frequent tripping and even falling in motion
5 Lateral pressure ulcers
Degrees of ataxia (to: Mayhew et al., 1978).

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A diagnostic
flowchart relating to
clinical signs to
specific regions of the
nervous system.
(Adapted from Furr M
and Reed S [2008].)

25. Reference
• Rijckaert, J. & Lefère, L. & van Loon, G., (2017) “Equine neurologic examination in practice”, Vlaams
Diergeneeskundig Tijdschrift 86(1), 47-55. doi: https://doi.org/10.21825/vdt.v86i1.16304
• https://www.ivis.org/library/aaep/aaep-annual-convention-baltimore-2010/how-to-perform-a-complete-
neurologic-examination-field-and-identify-abnormalities
• https://www.vettimes.co.uk/app/uploads/wp-post-to-pdf-enhanced-cache/1/equine-lameness-exploring-
conditions-underlying-neurological-causes.pdf
• https://www.rossdales.com/assets/files/Neurologic-conditions-in-the-horse.pdf
• https://www.veterinary-practice.com/article/performing-a-meaningful-neurological-exam
• https://www.nwvetmountvernon.com/site/equine-veterinary-mount-vernon/neurologic-exams
• https://en.wikivet.net/Neurological_Examination_of_Horses_Overview
• https://practicalhorsemanmag.com/health-archive/equine-neurological-disorders-signs-11614/
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Can you now evaluate
my neurological status?