Intervertebral disc disease and spinal disorders
(Clare Rusbridge 2018 ©)
Chondrodystrophic dogs (characteristically have disproportionably short limbs) for example the Bassett Hound, Dachshund, Lucas terriers, Sealyhams and Shih Tzus are predisposed to intervertebral disc disease
The most common sign is pain localised to the back or neck. Apart from yelping, common signs of spinal pain are abnormal posture (e.g. hunched back with head down), shivering, panting, unwillingness to move and difficulty jumping / doing stairs. In more severe cases there may be difficulty walking – ranging from poor control of the hindlimbs to complete paralysis. Most severe cases have a paralysed bladder and may be unable to urinate and / or dribble urine. The most severe cases are paralysed, have lost bladder function and have lost the ability to feel painful sensations.
How is disc disease diagnosed?
Disc disease may be strongly suspected on the basis of clinical signs especially in predisposed breeds however diagnostic imaging is required to confrim the diagnosis. Spinal radiographs (x-rays) may reveal characteristic changes of disc disease e.g. calcified disc material within the vertebral canal or narrowing of the IVD space or the foramen however radiographs rarely provide the accurate conformation and localisation required for surgical management. In some cases myelography is recommended. This is a radiograph where a contrast agent (i.e. similar to dye) is put into the space surrounding the spinal cord so that the outline of the spinal cord can be appreciated.
Do you have to operate?
Many cases will do well when managed conservatively (see below) however in cases with paralysis the prognosis is better with surgery i.e. the dog or cat is more likely to regain walking function and be pain free; is more likely to improve quickly; and is less likely to have recurrences. Cases where pain sensation is absence (i.e. when the toe is pinched hard but the dog or cat is unaware of discomfort) are a surgical emergency and have a poor prognosis for improvement.
Conservative management has the advantage that it is comparatively inexpensive and avoids surgery. The most important aspect is restriction of movement i.e. cage or crate confinement. This limits further IVD extrusion and exacerbation of the injury. The animal’s natural healing process can then repair the damage to the spinal cord. Pain relief should be given as necessary however the animal must be restricted otherwise they can exacerbate the injury. For pain relief the author prefers to use licenced NSAID analgesics in combination with opioids. The author avoids corticosteroids for treating IVD disease.Conservative management is indicated for patients with pain only or for those with mild deficits although there may be success with more severe case. Dogs which have lost pain sensation are a surgical emergency and are extremely unlikely to respond to conservative management. Disadvantages of conservative management include a higher rate of recurrence of clinical signs and a higher chance of deterioration or persistent neurological deficits. In addition diagnostic tests may not be performed so the animal may be receiving inappropriate treatment. A protocol for conservative management is detailed on the image.
What does the surgery involve?
There are two categories of disc surgery. The easiest and one that does not require specialised equipment is fenestration. In this procedure the nuclei pulposus of T11/T12 to L3/L4 (in the case of a thoracolumbar disc extrusion) or all the cervical intervertebral spaces (in the instance of cervical disc disease) are removed through a small window in the anulus fibrosis. This is a prophylactic procedure limiting further disc extrusions. The disc material within the vertebral canal is not removed and if the dog has severe spinal cord compression then the neurological recovery will be prolonged and/or there will be residual neurological deficits. At Fitzpatrick Referrals fenestrations are usually done in combination with a decompressive technique (below).
The second type of surgery is decompressive i.e. the extruded disc material is removed from the vertebral canal. This surgery is more technically difficult and requires specialised equipment and training. The type of decompressive surgery performed depends on the site of the problem. In the neck a ventral approach is favoured (ventral slot) and a window is drilled through the vertebral bodies. For the thoracolumbar spine, the most common procedure is a hemilaminectomy, where entry into the vertebral canal is made from the side, directly above the disc space and the vertebral foramen. For lumbosacral problems a dorsal laminectomy is used where the “roof” is taken off the vertebral canal allowing direct visualisation of the cauda equina and the lumbosacral disc.
The average hospital stay is 5 days after surgery. Patients are discharged when no longer requiring injectable pain killers and, for most cases, when they able to urinate voluntarily and starting to show signs of recoveryHow long before my paralysed dog will walk again?
This is very variable – typically recovery occurs several weeks. Some cases improve more quickly and, sadly, in some cases there is no improvement. The success rate of spinal surgery at Fitzpatrick Referrals is ~ 90%.
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