Spinal magnetic resonance imaging in cats: differences in clinical significance of intervertebral disk extrusion, intervertebral disk protrusion, and degenerative lumbosacral stenosis.

Objective: To determine the occurrence of degenerative changes affecting the vertebral column in cats, assess their clinical significance, and determine the occurrence in cats with intervertebral disk herniation compared to other spinal diseases.

Animals: 114 client-owned cats.

Methods: Hospital records were retrospectively reviewed for cats with suspected myelopathy that had undergone spinal MRI. Signalment; history; neurological examination; neurolocalization; primary diagnosis; presence, type, and location of intervertebral disk herniation; and presence and location of other degenerative spinal changes (intervertebral disk degeneration [IVDD], spondylosis deformans [SD], end plate changes, dorsal compressions [DC], and foraminal stenosis [FS]) were recorded.

Results: 70% of cats showed at least 1 spinal degenerative change. The most common change was IVDD, followed by SD and intervertebral disk protrusion (IVDP), while intervertebral disk extrusion (IVDE), end plate changes, DC, and FS were uncommon to rare. Primary complaint was attributed to a degenerative condition in 22% of cats, including 100% with IVDE, 9% with IVDP, and 43% with degenerative lumbosacral stenosis (DLSS). The occurrence of degenerative spinal changes and number of intervertebral disks affected by IVDD significantly increased with age and body weight. Age was positively correlated with the occurrence of SD and DLSS. Intervertebral disk degeneration, IVDP, SD, DC, and FS were more prevalent in the lumbosacral junction. Cats with IVDD were significantly more likely to show IVDE and IVDP.

Clinical Relevance: This study revealed that in a population of cats presenting for signs of myelopathy, IVDE was always responsible for the clinical presentation, DLSS was commonly considered incidental, and IVDP was infrequently related to neurological signs.