Computed tomography of the normal canine lumbosacral spine: A morphologic perspective

Daniel A. Feeney, Petra Evers, Thomas F. Fletcher, Robert M. Hardy, Larry J. Wallace

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


The lumbosacral spine of six normal dogs weighing 4.5 to 24.5 kg was imaged by computed tomography in 5.0 mm & 10.0 mm transverse planes. The vertebral canal and thecal sac (including emerging nerve roots not distinguished as separate structures from the spinal cord) were measured along dorsoventral and transverse dimensions at cranial, middle and caudal levels within each vertebra from transverse tomographic images. Linear measurements were standardized to the dorsoventral dimension of the L6 vertebral midbody to permit comparison and averaging of the vertebral and thecal sac dimensions among different sized dogs. The dorsoventral and transverse vertebral canal size progressively increased from cranial to caudal within each vertebra from L1-L6 (p ≤ 0.05). The transverse dimension of the thecal sac image increased caudally within each vertebra from L1-L4 (p ≤ 0.05). The vertebral canal dorsoventral and transverse dimensions were largest in the mid lumbar area (p ≤ 0.05). The transverse, but not the dorsoventral, imaged dimension of the thecal sac peaked in the L4 vertebra (p ≤ 0.05). The dorsoventral thecal sac image was observed to fill the vertebral canal in the cranial and middle vertebral levels in vertebrae L1 through L5 in over 60% of these normal dogs. However, epidural fat could almost always be seen lateral to the thecal sac regardless of what lumbar vertebra or vertebral level was imaged. Cranial to the lumbosacral junction, the dorsal intervertebral disk margin was almost always concave relative to the thecal sac. However, at the L7-S1 junction, some dogs had flat or even slightly convex dorsal intervertebral disk margins. The dorsal and ventral longitudinal ligaments and the ligamentum flavum could not be identified as distinct structures on the 5.0 mm transverse tomographic images.

Original languageEnglish (US)
Pages (from-to)399-411
Number of pages13
JournalVeterinary Radiology and Ultrasound
Issue number6
StatePublished - 1996


  • CT
  • Computed tomography
  • Dog
  • Intervertebral disk
  • Lumbosacral spine
  • Normal
  • Thecal sac
  • Vertebral body


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