“Jackson” is a five year old Jack Russell Terrier. Jackson presented with an acute onset of hind limb weakness four days prior to the MR examination. There was a mild improvement initially and then a rapid deterioration. On examination, there was no pain.
Sequences included T2-weighted sequences in sagittal and transverse planes, STIR sequences in sagittal and dorsal planes, and an MR myelogram.
A readily visualized disc herniation is seen at T12-13. This disc herniation can be seen in figure 1, the T2-weighted sagittal sequence. The fact that there is spinal cord compression is readily seen with the MR myelogram in figure 2. An MR myelogram is a technique to see only the cerebral spinal fluid. No injections are needed. This procedure is totally safe and without the pain and seizures that can accompany conventional myelography.
On figure 3, the herniated disc material can be seen in the ventral and right parasagittal spinal canal. There is loss of the subarachnoid space and spinal cord deformity. The presence of a normal seven lumbar vertebrae with the disc herniation at T12-13 can be confirmed on figure 4. These studies are necessary, as dogs can have 6, 7, or 8 lumbar vertebrae, which would change the surgical approach. Assumption of 7 lumbar vertebrae can be erroneous and lend to surgical problems.
Magnetic resonance imaging for the diagnosis of intervertebral disc herniation has greatly improved clinical outcomes. Contrast myelography, which creates inflammation, adds pain and a degree of complication can now be avoided. In addition, magnetic resonance imaging allows for the clear visualization of the herniated material, facilitating the surgical approach. Contrast myelography had a high error rate as to the side of the herniated disc material. With magnetic resonance imaging, the correct side can be chosen to facilitate complete disc removal and better surgical outcome.
It is our belief that since we have stopped doing conventional contrast myelography, the patients do better following surgery and leave the hospital quicker with a better return to function.