CS - Wobbly animal Flashcards
What is IVDD?
- chondroid degeneration
- extrusion of degenerate nucleus
- Acute –> spinal cord trauma (contusion or compression)
What animals tend to be affected by IVDD?
- Chondrodystrophoid breeds (Dachshunds, Basset Hounds, beagles, corgis)
- Potentially non-chondrodystrophoid breeds and large breeds as well (less common)
- Young (>3yo) to middle age and older
What are radiographic signs for IVDD? Which of these are specific for type 1 and 2?
- Spondylosis deformans (bony bridging) (Type 2)
- Mineralisation of IVD (seen with type 1 / chondroid degeneration) - (Type 1)
- Narrowed IVD space
- End-plate sclerosis (Type 2)
- Others: narrowed articular process joint space (Type 1), increased opacity of intervetebral foramen, spondylosis
- Radiographs aren’t diagnostic for spinal cord compression
Outline advantages/ disadvantages of radiographs
- ADVANTAGES – widely available, cheap, GA not essential but possible
- DISADVANTAGES – doesn’t show SC or nerve roots, therefore cannot confirm presence or site of spinal compression, difficult to interpret if not optimally positioned, radiation exposure
What is myelography?
contrast into subarachnoid space + radiograph
What is an extradural pattern
impression of outline of disc material – doesn’t directly visualised disc material
Advantages/ disadvantages of myelography
- ADVANTAGES: more available and cheaper than CT or MRI, good visualisation of extradural compression of sub-arachnoid space
- DISADVANTAGES: possible morbidity or neuro deterioration, technical skill/ operator dependent, possible adverse effects (post-myelographic seizures, infection), does not image spinal cord parenchyma, radiation exposure
Advantages/ disadvantages of CT?
- ADVANTAGES: allows transvere imaging (reformatted into any plane), excellent spatial resolution, excellent visualisation of both or other mineralised tissue.
- DISADVANTAGES– cost, availability, poor visualisation of SC parenchyma, may not visualised compression if not mineralised
Advantages/ disadvantages of MRI
- ADVANTAGES: imaging in any plane, excellent contrast resolution of soft tissues, directly visualise SC and nn roots, no radiation exposure
- DISADVANTAGES: cost, limited availability, poorer spatial resolution than CT (may get significant slice thickness artefacts in small dogs and cats)
Aim - medical tx of IVDD in dogs
AIM: compressive material dissipates and the dorsal annulus heals over so more NP material does not herniate.
Outline medical tx of IVDD in dogs
- Strict cage rest (most important part), minimum 6 weeks (annulus repair),
- NSAIDs or narcotic analgesics for first 3-5 days if strict confinement likely to be enforced
- Mm relaxants (Methocarbamol) to decrease painful mm spasms
- GCs (prednisolone): many vets tx with these to decrease pain for first few days, no evidence to support long-term outcome, high risk of GIT side effects even with low doses. Never with NSAIDs. Not for acute spinal cord injury.
- Evaluate frequently for deterioration in neurologic status if tx medically
- Gentle physio + short lead walks (
What are the indications for medical tx of IVDD?
- single episode of pain + normal neurologic exam
- mild rear limb neuro deficits but dog still able to rise and walk unassisted.
- failure to improve within 5-7 days or neurological deterioration should prompt recommendation for sx intervention.
- Dogs with thoracolumbar disk extrusions rarely have uncontrollable pain or recurrent episodes of pain, but sx.
Tx - thoracolumbar disc extrusions?
Most dogs recover from an episode of disk-related thoracolumbar pain with strict medical tx
Disadvantages - conservative management of IVDD
a higher rate of recurrence of CS and a higher chance of deterioration or persistent neurological deficits.
Indivations - sx tx of IVDD
- when decompression will significantly increase likelihood and completeness of recovery
- intractable or recurrent pain
- neurologic deficits +/- pain.
- All patients unable to walk at presentation.
- All dogs with signs suggesting less severe SC compression (paresis, pain) if neurologic signs don’t rapidly resolve with medical tx.
- Dogs which have lost pain sensation are a surgical emergency and are extremely unlikely to respond to conservative management.
Pros - sx tx of IVDD in dogs - 2
rate of recovery faster after decompression than non-sx and likelihood of residual neurologic deficits is decreased.
Define laminectomy
remove dorsal lamina of vertebral canal
Method of decompression for IVDD
decompression usually via a hemilaminectomy and extruded disk material is removed from spinal canal. Technically difficult – specialised equipment and training. Many surgeons also recommend concurrent fenestration of affected site and adjacent high risk sites to help decrease likelihood of subsequent herniations. In a fenestration - the NPs are removed through a small window created in the AF. This is a prophylactic procedure limiting further disc extrusions.
Post sx (IVDD - hemilaminectomy)- recommendations
keep calm and confined, padded bedding, frequent turning, manual bladder expression (min 4 times a day) an indwelling catheter or intermittent aseptic catheterisation. Swimming after skin incision healed. Paraplegic cart can provide stimulus for recovery.
Prognosis - IVDD post-surgery versus medical tx
Improvement in neuro fxn usually within 1 week. No improvement after 21d suggests poor prognosis. - Excluding loss of deep pain sensation, both conservative and sx tx have good prognoses (>80% for medical, generally >95% with surgery). Time to recovery is faster with surgery (because you are rapidly decompressing the SC).
What are the prognoses for IVDD with surgical intervention when considering absence/presence of deep pain sensation
o Deep pain sensation intact >90% dogs will improve
o Loss of deep pain for 48 hours - little chance of improvement
Why can’t you localise a lesion to C1-C5 or C6-T2 in horses and instead say C1-T2?
some reflexes aren’t testable in the horse - e.g. patella reflex thus LMN reflexes can’t be differentiated in horses.
T/F: Trauma exacerbating an underlying CVM/S is quite common.
True
What is Ryegrass staggers?
(occasionally UK, warmer and damper climates – NZ, fungus which infects ryegrass)
