Degenerative Myelopathy
Of German Shepherd Dogs
• A chronic, progressive
neurodegenerative disease
• Initial signs are due to TL
spinal cord disease
• Represents an autoimmune disorder
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Degenerative Myelopathy
Signalment
• Breeds
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–
–
–
–
–
• Sex
German Shepherd dogs
Belgium Shepherds
Old English Sheepdogs
Rhodesian Ridgebacks
Weimaraner
Probably Great Pyrenes
• Age
– Equal
• Onset
– 1 month to 1 year
• Clinical Course
– Paralysis within 3 to 6
month without
treatment
– > 5 years old (usually 8-9)
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Degenerative Myelopathy
Similar Conditions in Human Beings
• Multiple Sclerosis
– Immune-related demyelinating disorder
• Amyotrophic Lateral Sclerosis
– Axonal losing disease
• Genetic
• Free-radical association
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Degenerative Myelopathy
Progression
Time
Clinical Disease
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Degenerative Myelopathy
Early Clinical Signs
• Mild Spinal Ataxia
– Diminished Proprioception
– Slight Hyper-reflexia in Rear
Legs
• Rear Leg Weakness
– Slight Muscle Atrophy
• Occasionally, Atypical LMN
Dysfunction
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Degenerative Myelopathy
Late Clinical Signs
• Severe Spinal Ataxia
– Conscious Proprioceptive
Deficits
– Unconscious
Proprioceptive Deficits
– Crossed-extensor Reflex
– Babinski’s Sign
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Degenerative Myelopathy
Late Clinical Signs
• Severe Motor Weakness
– Loss of Weight Bearing
– Moderate Rear Leg Muscle
Atrophy
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Degenerative Myelopathy
Histopathology
• Axon and myelin loss
– Swollen axons
– Patchy demyelination
• Astrocyte proliferation
• Increase in vasculature
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Degenerative Myelopathy
Diagnosis
• Physical and Neurologic Examination
– History of chronic progressive posterior paresis
in susceptible breed
– TL (non-localized) dysfunction
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Degenerative Myelopathy
Diagnosis
• EMG
– Needle EMG- -normal
– NCV- -normal
– Repetitive Nerve Stimulation- -nondecremental
– Spinal Evoked Potential- -abnormal
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Degenerative Myelopathy
Spinal Evoked Potential
• a. Normal
• b. Early DM
• c. Late DM
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Degenerative Myelopathy
Diagnosis
• CSF tap (lumbar)
– Increased protein with normal cells
– Elevated inflammatory proteins
– Increased acetylcholinesterase levels (2 X
normal)
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Degenerative Myelopathy
Diagnosis
• Spinal Radiographs
– Plain radiographs- -spondylosis & spinal
arthritis
– Myelography- -no significant lesions
• Immune Studies
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Degenerative Myelopathy
CSF Analysis
• Lumbar CSF tap and analysis
– Normal cellularity
– Slight to moderate increase in protein
content 80-120 mg/dl
• Normal BB Barrier
– 258.4 + 92.7
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Degenerative Myelopathy
2-D Electrophoresis of CSF
• Normal
• DM
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Degenerative Myelopathy
CSF Cholinesterase
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Degenerative Myelopathy
CSF Inflammatory Markers
• Increased Inflammatory Markers
– IL6
– ICAM
– Leukotreine C, D, E
• No Markers for:
– viral and bacterial infection
– prion infection
– TNF
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Degenerative Myelopathy
Current Hypothesis
• An Auto-Immune CNS Disease
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Immune-complexes damage endothelium
Leads to perivascular fibrin deposition
Fibrin degradation leads to leukocyte infiltration
Leukocytes produce prostaglandins and
leukotreines
– Leads to Free-Radical production and damage
• Treatment must take these steps into account
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