Acquired scoliosis of the cervical spine secondary to vertebral neoplasia in an aged pony gelding

Abstract

SummaryA 20‐year‐old New Forest pony gelding presented for investigation of a firm swelling on the right side of the neck and a variably sized patch of sweating on the right side of the cranial neck. Clinical examination revealed moderate scoliosis with right side convexity centred on the mid‐caudal cervical spine. Initial radiographic examination of the cervical spine showed very subtle heterogeneously increased opacity of the vertebral body of the fifth cervical vertebra (C5). Further investigations were declined by the owner. The pony’s clinical condition deteriorated over the following 6 weeks; at this stage, the pony showed proprioceptive deficits of both fore‐ and hindlimbs (grade 1/5 and 3/5 respectively) and difficulty lowering his head to eat from the ground. Repeat radiographs showed mildly increased opacity of the vertebral body of C5 with a small amount of new bone formation ventrally. Neoplasia of the fifth cervical vertebra was suspected. In view of the clinical deterioration and the likely very poor prognosis, the pony was subjected to euthanasia. Post‐mortem computed tomographic examination showed heterogeneously increased attenuation surrounding small, poorly defined regions of reduced attenuation in the trabecular bone of the vertebral body and right transverse process of C5. There was also moderate, irregular periosteal new bone formation on the fifth and sixth cervical vertebrae with a poorly defined mildly hyperattenuating soft tissue structure adjacent to the right pedicle of C5 and extending into the right side of the vertebral canal, compressing the spinal cord to the left side. Post‐mortem examination revealed tan‐coloured tissue running along the right side of the C5 vertebral body, into the right side of the vertebral canal, compressing the spinal cord to the left side and invading adjacent epaxial muscles. Histopathological examination of this tissue was consistent with an undifferentiated sarcoma. To the authors’ knowledge this is the first report of acquired scoliosis secondary to cervical neoplasia in a horse or pony.