A 15 month old Jack Russell terrier presented with at least a 6 month history of non-painful, progressive paraparesis and general proprioceptive ataxia.
 

MR study shows a smooth bony proliferation arising from the lamina of T5 and impinging on the vertebral canal causing severe extradural cord compression. This mass blends with the normal bone tissue of the affected vertebra having similar signal intensity. It has a distinct, smooth, curvilinear T2W hyperintense and T1W hypointense cap in its ventral margin. Mild homogeneous contrast enhancement is present. The paravertebral tissues are normal.

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CT study shows a bony proliferation originating from the lamina of T5. As with the MR study, this mass has a smooth border and blends with the normal bone tissue of T5 having similar appearance with medullary continuity. There is marked remodeling of the cranial articular processes and cranial pedicles of T6, particularly pronounced on the left side. No periosteal reactions of the adjacent bone indicating infectious or malignant behaviour are present.

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In conclusion, a smooth bony proliferation arising from the lamina of T5 causing dorsal extradural cord compression is strongly suggestive of osteochondroma which was confirmed histologically after surgical excision.

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Click the link below to read a case report of a Golden retriever with a similar presentation.

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Courtesy of Dr Emil Olsen from the Swedish University of Agricultural Sciences, Veterinary Teaching Hospital, Uppsala, Sweden.

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