Scotty Dog Sign - Orthopaedia

Location	Spine
Diagnosis	Spondylolysis
Discussion	On the oblique view of the lumbar spine, the outline of a dog can seen. The parts of the dog are as follows: the transverse process-the nose; the pedicle-the eye; the pars interarticularis-the neck; the superior articular facet-the ear; the inferior articular facet-the front leg. A break in the neck of the dog, or a dog collar, corresponds to a fracture in the region of the pars interarticularis, which is specific for spondylolysis. It is important to recognize as it is a cause of low back pain. A. Normal. B. L5 Pars defect.
Reference	Millard L: The Scotty dog and his collar. J Ark Med Soc 1976 Jan;72(8):339-40.