Scottie Dog Sign

‘With a little imagination,’ one can detect the form of a small dog in the outline of a lumbar vertebral body’s parts as seen on an oblique radiograph (Figure 1). This simple observation, reported by A.-P. Lachapèle ¹ in 1938, has provided radiologists with an easy method of remembering the complex anatomy in this crucial area. Lachapèle (Hopital Saint-Andre’ de Bordeaux) compared the anatomic outline to Pol Rab’s cartoon character Scottish terrier ‘Rac’ ² (Figures 2 and 3), thus giving us the ‘Scottie dog.’ The most important feature is the ‘neck’ of the Scottie dog. This corresponds to the pars interarticularis and it is the site of abnormality when spondylolysis is present. A break in the neck of the dog or a collar on the dog’s neck is indicative of spondylolysis. In the very next article in the journal Lachapèle ³ discussed cases of spondylolysis and illustrated how the ‘Scottie dog’ analogy applies to the radiographic findings. A renewed emphasis was placed on the importance of spondylolysis detection in the 1950s because of the increased use of preplacement lumbar spine X-rays for industrial workers and heavy laborers. Figure 1 ‘The posterior arches of the examined side are whimsically stylized like a small dog.’ Reprinted from Lachapele<xref ref-type="bibr" rid="ref76_1"> ¹ </xref>. Un moyen simple pour faciliter la lecture des radiographies vertebrales obliques de la region lombo-sacree. Bull et <italic>Mem. Soc Bectro-radiol. Med. de France,</italic> 1939,27, 175–176 https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003076568/34c29fd5-5662-4e8f-b58c-badd7fa5d724/content/fig76_1_B.jpg"/> Figure 2 Posterior oblique radiograph of lumbar spine showing the Scottie dog (author’s case) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003076568/34c29fd5-5662-4e8f-b58c-badd7fa5d724/content/fig76_2_B.jpg"/> Figure 3 Pol Rab’s dog ‘Rac’. Reprinted from <italic>‘Pas Pour jeunes Filles’:</italic> 125 <italic>Réflexions de Ric et Rac</italic> by Rab (1930)<xref ref-type="bibr" rid="ref76_2"> ² </xref> published by Artheme Fayard and Cie, Paris https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003076568/34c29fd5-5662-4e8f-b58c-badd7fa5d724/content/fig76_3_B.jpg"/>