A fi veyear-old Standardbred trotter showed a decreased level of performance and signs suggestive of pain after exercise. The horse had performed well earlier. Based on initial examinations, a mild inflammatory airway disease was diagnosed. The main finding in further examinations was a radiographically evident, advanced spondylosis bridging two cranial thoracic vertebrae. Despite treatment and periods of rest, the horse’s signs worsened and it was euthanised. In necropsy, the spondylosis was surrounded by fi brous tissue. The horse also had signs of ataxia, which could not be explained by the fi ndings. While the aetiology of the spondylosis remained undetermined, previous trauma or infection was suspected.