50 - IVDD
chondrodystrophic breeds
dachshund
beagle
pekingese
french bulldog
cocker spaniel
anatomy
intervertebral disks are only located in the thoracolumbar region
Intervertebral disks
annulus fibrosis
fibrocartilaginous lamellae
thicker ventrally
nucleus pulposus
amorphous gel
absorbs compressive loads
Cartilagenous end plates
between disk and veterbra
hyaline cartilage
primary supplier of disk nutrition
spinal meninges
dura mater → outermost
arachnoid mater
subarachnoid space → collect CSF, inject contrast
pia mater → closest to cord
spinal vasculature
paired vertebral venous sinuses
more lateralized in the thoracolumbar spin compared to cervical spine → surgical concern
nerves
superficial to deep → proprioception, voluntary muscle control, superficial pain, deep pain
disk degeneration/chondroid metaplasia
degeneration of nucleus pulposus → loss of water and prteoglycan molecules, increased collagen, calcification
what happens in chondrodysplastic breeds → occurs quickly, when young (first year)
fibroid degeneration
non-chondrodysplastics
slow, insidious process → geriatric animals
Hanson classifications
Type I
herniation of nucleus pulposus through annulus
extrudes into spinal canal
acute onset → chondrodysplastic breeds
Type II
protrusion of annulus into spinal canal
slow, progressive → nonchondrodystrophic
Type III
extrusion of small volume of nucleus pulposus through annulus WITH contusion of spinal cord without compression
spinal cord injury
primary trauma
inflammation
focal hemorrhage
spinal cord swelling
initiation of secondary mechanism of injury
secondary mechanisms
vasoconstrictive substances → ischemic injury
increased intracellular calcium → impaired metabolism
formation of lipid peroxidases → chemical damage
diagnosis
survey radiographs
limited accuracy in localization
essential for differential diagnosis
pt needs to be anesthetized
look for narrowing/wedging of disk space
alteration of intervertebral foramen shape
presence of mineralized disk material
myelography
iohexol or iopamidol contrast agent
collect CSF prior to procedure
clinical presentation
assess conscious proprioception
assess superficial pain
assess deep apin
differentials
fibrocartilagenous emboli
spinal fracture/luxation
neoplasm
diskspondylitis
meningitis/myelitis
treatment
conservative
strict immobilization for 3 weeks
outcomes
resolution of inflammation
resorption
fibrosis
surgical
hemilaminectomy
pediculectomy
modified dorsal laminectomy
fenestration/laser ablation
not a sole treatment for IVDD
may be effective when combined with decompressive surgery
outcomes
favorable with surgery when deep pain is present
recovery in <1 mo
when deep pain is lost
50% success rate w/in 12 hours
<50% success if >12 hrs
poor prog if deep pain is absent >48 hrs
nursing care
express bladder BID/QID
physical therapy
cervical disk disease
arched back
head down
one front leg up
differentials
fibrocartilagenous emboli
osteoarthritis
wobbler’s
fracture/luxation
neoplasm
atlantoaxial instability
meningitis/myelitis
diskospondylitis
treatment
conservative same as IVDD + more responsive to steroids
surgical
vetnral slot
dorsolateral hemilaminectomy
prognosis
excellent for dogs with neck/forelimb pain only
75% recovery in non-ambulatory dogs with forelimb sensation
guarded prog if non-ambulatory with no forelimb sensation