Disc Protrusion

From WikiVet English
Jump to navigation Jump to search
Intervertebral disc degeneration (Image sourced from Bristol Biomed Image Archive with permission)
  • Occurs mainly in dogs
  • Almost always dorsal protrusion due to eccentric position of nucleus pulposus
  • Main sites are cervical and lumbar regions
  • Degeneration precedes protrusion (two patterns):
    • Chondroid
      • In chondrodystrophic breeds
      • Concurrent calcification of degenerated nucleus pulposus
      • Progressive loosening and fragmentation of overlying annulus fibrosis fibres
        • Damaged by both compressive and rotational forces
      • Predisposing degeneration of the discs occurs by one year of age in most of the dogs
      • Protrusion usually occurs in males, 3-6 years of age
      • Sudden complete protrusion -> severe damage to spinal cord in the area
      • Widespread necrosis and haemorrhage
      • Extruded material is gritty, hemorrhagic or “cheesy”
    • Fibroid
      • In non-chondrodystrophic breeds, horses, pigs
      • Usually occurs later in life
      • Pathogenesis:
        • Progressive dehydration and collagenisation of nucleus pulposus
        • Fraying and fragmentation of lamellar annulus fibrosis fibres
        • -> Attempts to repair by fibrosis
        • -> Weak area in the annulus
        • -> Partial protrusion (rarely may calcify) of nucleus into spinal canal
          • May be dorsal or lateral
        • -> Pressure on spinal cord
        • -> Demyelination of white matter
        • -> Progressive weakness of structures innervated distally to the lesion
      • Disk material may enter blood vessels causing fibrocartilagenous embolism
        • May present without any disk symptoms

  • Sudden protrusion can occur in any breed due to traumatic compression of spinal cord