SUMMARY An aortic body tumour in a 7-year-old wire-haired fox terrier with hindlimb ataxia is described. A metastatic lesion in the dorsal arch of the eighth thoracic vertebra caused compression of the spinal cord. Radiographic techniques are discussed that enabled the position and extent of the primarytumour and its metastasis to be defined and allowed a provisional diagnosisof chemodectoma.