Discussion: CT, conventional myelography, or CT myelography could have been helpful in diagnosing this dog's problem. MRI was chosen over CT in this case because of the lack of radiographic evidence of calcified intervertebral disks. A non-calcified disk herniation would not have been well visualized on CT (see CT vs MRI). A CT myelogram would likely have shown the lesion but is more invasive and shows less detail than MRI. Conservative management in patients with disk herniations is generally unrewarding.

The MRI revealed the following images (click to enlarge):

Warner SagT2 Large Warner SagT1 Large

Question: Based on the previous findings and these MR images, what is the most likely cause of this patient's problem?