Intervertebral Disc Disease
Intervertebral discs are the shock absorbers of the spinal column. There is an intervertebral disc situated between every two vertebral bodies. Each disc has an outer ring of fibrous tissue and an inner core of gelatinous material (think of a jelly filled donut from Tim's). The spinal canal sits above the vertebral bodies and discs and is the space that contains the spinal cord. The spinal cord is the neural highway between the brain and all other tissues and organs in the body. If the spinal cord becomes damaged, loss of function occurs (much like the endless delays associated with the summer construction season on the Anthony Henday!)
Dogs with a short limbed, long backed conformation (so called chondrodystrophic breeds) are genetically predisposed to degeneration of their intervertebral discs (IVDD). The central gelatinous portion of the disc degenerates and becomes hard and inelastic. Force is exerted on the outer fibrous ring of the disc and eventually the central core of the disc can tear through the outer ring of the disc and herniate (or rupture) into the spinal canal. The velocity of the herniation can cause bruising of the spinal cord, and compression of the spinal cord caused by herniated disc material within the spinal canal causes ongoing spinal cord loss of function.
How do I know if my dog might have a herniated disc? Dogs with IVDD usually have an acute onset of clinical signs. In its mildest form IVDD causes acute onset of back or neck pain (depending on the location of the disc). With more severe spinal cord trauma and compression more significant loss of function is noted. Dogs may be able to walk but appear uncoordinated (the drunken sailor gait), or they may be completely paralyzed. Any sudden onset of clinical signs potentially associated with IVDD should be assessed on an emergency basis to avoid progressive spinal cord injury.
Based on an initial neurologic assessment the veterinarians at Guardian will determine the likelihood that your pet is suffering from IVDD, the severity of associated spinal cord injury, and the general location of the injury within the spinal cord. Dogs presenting only with back pain may be initially managed conservatively using pain medications and restriction of activity. If loss of spinal cord function is evident, further testing is indicated. CT scans (computerized tomography) are routinely recommended. This allows a detailed picture of the spinal canal and discs so that the precise location of disc herniation and the severity of spinal cord compression can be appreciated. Surgical decompression of the spinal cord may be recommended based on severity of spinal injury, progression of clinical signs, and severity of spinal cord compression noted on the CT scan.
What can I expect after surgery? The prognosis or outcome after spinal decopmpression depends on the severity of spinal cord injury prior to surgery. Dogs that have the ability to feel pain sensation from the back legs prior to surgery have a 90% prognosis for return of ambulatory function after surgery. The speed of recovery is variable with most improvement noted over the first 6 weeks, but progressive improvemnet is often evident for up to one year after surgery. Dogs that lose ability to feel pain sensation from the back legs prior to surgery have a 50% prognosis for return of ability to walk.
IVDD, in most cases, can be treated successfully. Early diagnosis and treatment is important, however, to optimize outcomes. Any sudden onset of neck or back pain, loss of coordination, or inability to walk should be assessed on an emergency basis.