Thoracic hemivertebra is one of the rare congenital vertebral anomalies
in horses resulting in vertebral column deformity with or without
neurological signs. A nine-month-old Racking filly was presented with a
distinct bump over the back region. This bump was apparent at birth and
has been increasing in size. Clinical examination revealed a painless
kyphoscoliosis over the thoracic vertebrae with mild ataxia and abnormal
gait of hindlimbs. In plain lateral radiographs of thoracic vertebrae,
hemivertebrae were seen in the 13th-15th thoracic vertebrae. At
myelography performed under general anaesthesia, the ventral and dorsal
aspects of the contrast medium column were narrowing at the level of the
13th-14th thoracic vertebrae, and no sign of contrast medium after the
14th thoracic vertebra that represents spinal cord compression. Little
information about hemivertebra in horses exists and a better
understanding of hemivertebra etiology is required.