27/05/2026
“Scottish Dog Sign Explained 🐶 | The X-Ray Clue Behind Spondylolisthesis”
Scottish Dog Sign & Spondylolisthesis Explained 🐶🩻
The “Scottish Dog Sign” is a classic radiology finding seen on an oblique X-ray of the lumbar spine, especially useful for identifying spondylolysis and spondylolisthesis.
🐶 What is the Scottish Dog Sign?
On an oblique lumbar spine X-ray, the posterior elements of the vertebra resemble a Scottish Terrier dog.
Anatomy of the “Dog”
• Eye → Pedicle
• Nose → Transverse process
• Ear → Superior articular facet
• Front leg → Inferior articular facet
• Neck → Pars interarticularis
The most important part is the neck of the dog — this represents the pars interarticularis.
🦴 What is Spondylolysis?
Spondylolysis is a defect or stress fracture in the pars interarticularis, commonly involving L5 vertebra.
X-ray Finding
When there is a pars defect, the Scottish dog appears to have a collar around its neck.
➡️ “Dog with a collar” = Pars defect = Spondylolysis
Common Causes
• Repetitive spinal extension
• Gymnastics
• Cricket fast bowlers
• Weightlifting
• Athletes
• Trauma or stress injury
Symptoms
• Low back pain
• Pain during extension
• Tight hamstrings
• Pain after sports activity
🦴 What is Spondylolisthesis?
Spondylolisthesis occurs when one vertebra slips forward over the vertebra below it, often due to bilateral pars defects.
Most commonly: ➡️ L5 slips over S1
Relation to Scottish Dog Sign
If the pars defect progresses:
• The dog develops a collar (spondylolysis)
• Eventually the vertebra slips forward (spondylolisthesis)
📊 Grading of Spondylolisthesis
Based on percentage of vertebral slippage:
• Grade I →
