Diagnostic imaging of a basihyoid bone fracture and partial avulsion of the medial pterygoid muscle in a horse.

A 3-year-old gelding was presented for further evaluation and treatment of a swelling over the left mandible and inability to eat and drink. Radiographs of the mandible were unremarkable. Computed tomography (CT) of the head demonstrated a fracture of the basihyoid bone and partial avulsion of the medial pterygoid muscle. Ultrasound examination was performed to establish a baseline and confirmed the fracture. The gelding was managed conservatively, recovered uneventfully, and was able to return to training after 4 months of rest. Key clinical message: Computed tomography and ultrasonography in the horse provided information about injury to the basihyoid bone and insertion of the medial pterygoid muscle.