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| − | ===Disc protrusion=== | + | ===[[Disc Protrusion]]=== |
| − | [[Image:Intervertebral disc degeneration.jpg|right|thumb|100px|<small><center>Intervertebral disc degeneration (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]] | |
| − | *Occurs mainly in dogs
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| − | *Almost always '''dorsal''' protrusion due to eccentric position of [[Joints - Anatomy & Physiology#Fibrocartilagenous joints|''nucleus pulposus'']]
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| − | *Main sites are '''cervical and lumbar''' regions
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| − | **Thoracic vertebrae have [[Joints - Anatomy & Physiology#Fibrocartilagenous joints|conjugal ligaments]]
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| − | *Degeneration precedes protrusion (two patterns):
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| − | **'''Chondroid'''
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| − | ***In chondrodystrophic breeds
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| − | ***Concurrent calcification of [[Intervertebral disc degeneration|degenerated ''nucleus pulposus'']]
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| − | ***Progressive loosening and fragmentation of overlying ''annulus fibrosis'' fibres
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| − | ****Damaged by both compressive and rotational forces
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| − | ***Predisposing degeneration of the discs occurs by one year of age in most of the dogs
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| − | ***Protrusion usually occurs in males, 3-6 years of age
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| − | ***'''Sudden complete protrusion''' -> severe damage to spinal cord in the area
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| − | ***Widespread necrosis and haemorrhage
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| − | ***Extruded material is gritty, hemorrhagic or “cheesy”
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| − | **'''Fibroid'''
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| − | ***In non-chondrodystrophic breeds, horses, pigs
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| − | ***Usually occurs later in life
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| − | ***Pathogenesis:
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| − | ****Progressive dehydration and collagenisation of ''nucleus pulposus''
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| − | ****Fraying and fragmentation of lamellar ''annulus fibrosis'' fibres
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| − | **** -> Attempts to repair by fibrosis
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| − | **** -> Weak area in the annulus
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| − | **** -> '''Partial protrusion''' (rarely may calcify) of nucleus into spinal canal
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| − | *****May be dorsal or lateral
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| − | **** -> Pressure on spinal cord
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| − | **** -> Demyelination of white matter
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| − | **** -> Progressive weakness of structures innervated distally to the lesion
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| − | ***Disk material may enter blood vessels causing fibrocartilagenous embolism
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| − | ****May present without any disk symptoms
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| − | *'''Sudden protrusion''' can occur in any breed due to traumatic compression of spinal cord
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| − | [[Category:Joints - Degenerative Pathology]]
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| | ===Cervical spinal stenosis=== | | ===Cervical spinal stenosis=== |