Computed tomography findings in horses presented with signs of head-shaking.

Abstract

Trigeminal nerve-mediated head-shaking (TNMH) in horses is a diagnosis made by exclusion. Computed tomography (CT) is frequently used to identify any disease process that could cause the clinical signs of head-shaking. Although abnormalities are frequently identified, it is unknown whether treatment of these conditions improves clinical signs. To ascertain the clinical significance of CT findings in horses presented with a complaint of head-shaking. Retrospective case series. CT and patient records were reviewed and all abnormal findings and any treatments subsequently carried out was recorded. A questionnaire was sent to referring veterinarians and owners were contacted by telephone to establish whether treatment of the identified condition improved clinical signs. This study included 103 horses presented for head CT with the complaint of head-shaking with follow-up information obtained for 84 horses (81.6%). The diagnosis of TNMH was based on a combination of positive maxillary nerve block and/or response to treatment for TNMH. Although TNMH was the most common diagnosis with 62 horses (60.2%) affected, in 22 horses (21.4%), a primary disease process was identified and treatment of the condition eliminated signs of head-shaking. Clinically relevant primary diseases included dental fracture, primary sinusitis, temporo-mandibular joint arthritis, nuchal bursitis, musculoskeletal pathologies, basisphenoid fracture, otitis externa and a mass affecting the infra-orbital nerve. Some clinical information was missing and follow-up information was not obtained in all cases. CT was perceived as a useful diagnostic tool by most veterinarians, ruling out significant abnormalities. In over 20% of the cases, a treatable primary condition was identified leading to complete resolution of clinical signs.