Equine Neurologic Examination Flashcards
What are some signs of decreased consciousness? What are 4 causes?
depression, obtundation, stupor, coma
- cerebrum lesion
- brainstem lesion
- metabolic disturbance
- systemic illness
What are some signs of increased consciousness? What are 2 causes?
anxiety, mania, aggression, delirium, confusion
- cerebral cortical lesion
- encephalopathy
What are 3 common causes of seizures?
- forebrain lesion
- encephalopathy
- intoxication
What are some signs of lethargy in horses?
- blank facial expression
- drooping ears and eyelids
- sluggish responsiveness to stimuli
- reduced voluntary activity
What are some signs of stupor in horses?
- stands in one place
- head held low
- only responds to strong stimuli
What is the difference between semi-comatose and comatose states?
SEMI-COMATOSE = recumbent, but responds
COMATOSE = recumbent and unresponsive
What are some behaviors that indicate neurologic disease in horses?
- self-mutilation
- head pressing
- compulsive walking
- yawning
- head pressing
- aggression
- timidity
- loss of affection
- excessive flehmen
What are some postures that indicate neurologic disease in horses?
- wide/narrow-based stance
- tilt (peripheral vestibular)
- turn/circling (central)
- leaning
- recumbency
- opisthotonos
What are the 12 cranial nerves?
- olfactory
- optic
- oculomotor
- trochlear
- trigeminal
- abducens
- facial
- vestibulocochlear
- glossopharyngeal
- vagus
- accessory
- hypoglossal
What is the major function of the optic nerve? What 2 tests are used for assessment?
afferent pathway for vision and light
- menace
- PLR
What are the major functions of the oculomotor nerve? What 2 tests are used for assessment?
pupillary constriction and extraocular muscle movement
- PLR
- medial movement of the globe
What is the major function of the trochlear nerve? What test is used for assessment?
extraocular muscle movement (dorsal oblique)
ventrolateral rotation of globe
What are the sensory and motor functions of the trigeminal nerve? What tests are used for assessment?
SENSORY - head and face
- ear, eyelid, lip reflexes
- pain perception
MOTOR - mastication muscles
- chewing, jaw tone
- mascle mass (temporal, masseter, pterygoid)
What is the major function of the abducens nerve? What 2 tests are used for assessment?
extraocular muscle movement
- eyeball retraction (corneal reflex)
- lateral movement of globe
What is the major function of the facial nerve? What test is used for assessment?
innervates muscles of facial expression
ear, eyelid, and lip tone, reflexes, movements, and symmetry
What are the major functions of the vestibulocochlear nerve? What 6 tests are used for assessment?
afferent branch of the vestibular system and hearing
- head posture
- induced eyeball movement
- normal vestibular nystagmus
- gait
- blindfold test
- response to noise
What is the major function of the glossopharyngeal nerve? What 2 tests are used for assessment?
sensory/motor pharynx
- swallowing (observation, palpation)
- endoscopy
What is the major function of the vagus nerve? How is the accessory nerve assessed?
sensory/motor pharynx and larynx
slap test
What is the major function of the hypoglossal nerve? How is it assessed?
motor to tongue
tongue size and symmetry
Cranial nerve tests:
How are the upper eyelashes used to asses neurologic disease?
normally, eyelashes with be at an upward angle, but when horses are in pain or have some neurological disease, the eyelashes will begin to turn downward
How is the trigeminal nerve assessed? What are 2 effects when it is not working properly?
observe facial symmetry and test facial sensation
- atrophy of temporalis, masseter, and pterygoid nerves responsible for mastication
- loss of sensation
What is the facial nerve responsible for? What are signs of disease?
facial expression
unilateral drooping face —> general anesthesia and halter compression!
How is the body assessed for neurological deficits?
- observation
- palpation
- manipulation
How the body is affected by neurological deficits?
- atrophy
- asymmetry
- trembling
- sweating
How are C1-C5 commonly affected by neurological disease? Where is C-6-C7 found?
pain and deformation
deep in front of the shoulder
How can the neck be flexed to observe neurologic deficits?
have the horse follow a desirable treat to the side of its chest
- ensure the horse is able to lift and lower its head and neck
What other 3 reflexes are used to observe neurological deficits in the neck and thoracic limbs?
- slap test
- cervicofacial reflex
- cutaneous trunci (panniculus)
also assess limb strength and sensation, gait, and posture!
What is the slap test?
thoraco-laryngeal adductor reflex (TLAR) - highest point of the larynx is hooked in one hand and the other is used to slap the wither on the opposite side —> should feel a discrete movement of the arytenoid cartilage
What is palpated on the trunk and pelvic limbs to assess neurologic deficits?
- back extension (R)
- back flexion (G)
- cutaneous trunci
What are 4 parts to the nerurological exam in the rectum, bladder, anus, and tail area?
- anal reflex - should contract with palpation
- perineal sensation
- tail tone - should naturally have some resistance
- signs of incontinence
What are 2 major signs of cauda equina syndrome? Where in the CNS is this affected?
- flaccid paralysis of the tail, penis, and perineum
- spastic paralysis of the anus, rectum, and bladder
any part of the vertebrae past S2
How are lesions localized based on gait/posture?
- before T2 = all 4 legs affected
- past T2 = only hind legs affected
What is paresis?
weakness of voluntary resulting in inability to support weight and generate gait
- hemi = one side of the body
- tetra = all 4 legs
- para = 2 legs
What are signs of LMN and UPN injuries seen in the limbs?
LMN = weakness, short stride, narrow base, normal postural reaction
UMN = delayed protraction, long stride, abnormal postural reaction, stiffness
How are the limbs’ strength tested?
- hopping
- tail pull while standing = L3-L5
- tail pull while walking = cervical
What is ataxia? What are the 3 etiologies?
lack of voluntary muscle coordination
- cerebellar
- sensory
- vestibular
What are the most common signs of ataxia?
- scuffing and dragging
- delayed protraction, knuckling
- crossing over
- stepping on other feet
- pivoting, circumduction
- elongated stride
What is dysmetria? Hypermetria? Hypometria?
lack of coordination of movement
overshoot intended position
undershoot intended position
What is the difference between a lame horse and an ataxic horse?
LAME = regularly irregular, predictable
ATAXIC = irregularly irregular, unpredictable
What maneuvers are used to assess limb strength and gait?
LIMB STRENGTH - tail pull, hopping
GAIT - walk straight, trotting away and towards, serpentine, elevate head, blindfold, up and down curb, large and small circles, backing up, up and down hill
What is the point of the tail pull, trotting with an elevated head, blindfold, and curb tests?
horse should be able to resist and right themselves
can compress cervical canal and highlight neurological deficits
vestibular horses won’t be able to correct themselves
indicated proprioceptive/sight problems; check scuffing of hooves!
UMN vs. LMN
What are possible signs of neurological signs on CBC? Biochem?
inflammation and dehydration
- metabolic disorders
- electrolyte abnormalities
- enzymes
- ammonia
- vitamin E
What are the 3 methods of CSF collection in horses?
- atlantooccipital - lateral recumbency, GA
- C1-C2 - standing and US-guided, sedation
- lumbosacral - standing, sedation
What are the major complications associated with AO and C1-C2 collection of CSF?
AO - possible neurological impairment, anesthetic complications
C1-C2 - bleeding, depression, stiffness
What is a major pro and con to lumbosacral collection of CSF?
PRO - deep depth allowed
CON - harsh reactions common
How is the CSF grossly observed? What lab analyses can be performed?
pressure, color, turbidity, xanthochromia (yellow)
- TP
- TCC
- cytology
- enzymes
- immune testing
What neurological disease uses nasal swabs as a part of diagnosis?
EHV1
How are plain radiographs used to assess neurological disease?
create composites of the spinal column and search for any bone lesions or fractures
What sagittal ratios are used to evaluate for cervical vertebral stenotic myelopathy?
- C3-C5 = < 50% (A:B)
- C6 = < 52%
- C7 = < 56%
- any site = < 48% (C:B)
What is a myelogram? What are 5 possible complications? Why is this not commonly performed?
using contrast dye and X-rays/CT to look for problems in the spinal canal
- seizures
- blindness
- fever
- neck pain
- horse unable to rise
recovery of neurologic horses from GA is difficult
What are some neuroelectrodiagnostics?
- electromyography (EMG) = electrical activity by muscle
- nerve conduction studies (NCS) = electrical conduction by nerves
- brainstem auditory evoked response (BAER)
- electroencephalography (EEG)
What are EMGs and NCSs used to evaluate? What are positive responses?
electrical activity of muscle and nerve = LMN
- positive sharp waves
- fibrillation potential
