Sagittal T2‐weighted MR image of an 11‐year‐old Shih Tzu with intervertebral disc herniation and marked spinal cord compression at the level of Th11/12. Solid lines indicate intramedullary hyperintensities (T2WL), whereas the dotted line indicates spinal cord compression length (CL). Summation of solid and dotted lines represents T2W‐LE; division of these lengths by the lengths of L2 (not depicted here) create the dimensionless ratios T2‐weighted hyperintensity length ratio, compression length ratio, and T2‐weighted‐lesion extension ratio. The latter of the 3 ratios was calculated separately to account for possible overlapping of hyperintensities and regions of spinal cord compression