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, 18:41, 9 October 2007
<big><center>[[Joints - degenerative#Disc protrusion|'''BACK TO DISC PROTRUSION''']]</center></big>
<big>'''Intervertebral disk degeneration'''</big>
*Associated with loss of water from the nucleus pulposus due to lowering of proteoglycan content
**Reduces the cushioning function
**Can lead to herniation of the nucleus pulposus through the annular rings and impinge on the spinal cord.
*Breeds
**Dachshund (45-75% of cases), Pekingese, beagle, Lhaso apso and cocker spaniel
**Probably partly because all are chondrodysplastic to a varying degree
***Occurs in all disks simultaneously (cf: non chondrodysplastic dogs – degeneration in only one disk at a time).
***Chondrodysplastic dogs -> chondroid metaplasia of the nucleus pulposus, with progressive calcification
***Occurs at a young age … cf non-chondrodysplastic breeds , occurs as a senile change
***Progressive decrease in amount of glycosaminoglycans, and changes from chondroitin sulphate to keratin sulphate over the first few years of life
***Hansen type I protrusions – explosive and large
**Non-chondrodysplastic dogs -> progressive fibrous metaplasia of the nucleaus pulposus, starting at the periphery
***Increased amount of type I collagen (poor at withstanding compressive loads)
***Can lead with time, to bulging of the remaining nucleus pulposus dorsally, as it becomes increasingly constricted by the annular fibrosa
***Calcification is uncommon
***Hansen type II protrusions -> small and progressive