degenerative myelopathy copyright university of florida 1998 of german shepherd dogs a chronic,...
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Copyright University of Florida 1998
Degenerative Myelopathy
Of German Shepherd Dogs
• A chronic, progressive neurodegenerative disease
• Initial signs are due to TL spinal cord disease
• Represents an auto-immune disorder
Copyright University of Florida 1998
Degenerative Myelopathy
Signalment• Breeds
– German Shepherd dogs
– Belgium Shepherds
– Old English Sheepdogs
– Rhodesian Ridgebacks
– Weimaraner
– Probably Great Pyrenes
• Age– > 5 years old (usually 8-9)
• Sex– Equal
• Onset– 1 month to 1 year
• Clinical Course– Paralysis within 3 to 6
month without treatment
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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- -non-
decremental– 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
– 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