Unilateral synostosis of the zygo-maticotemporal suture associated with mandibular coronoid process impingement in a dog.

A 13-month-old dog was investigated for the complaint of open-mouth locked jaw. There were not any previous episodes of trauma witnessed. Computed tomographic evaluation revealed unilateral zygomatico-temporal synostosis and associated craniofacial asymmetry, with impingement of the mandibular coronoid process resulting in unilateral temporomandibular joint subluxation. Closed reduction of the subluxation was not maintained. Partial zygomatico-temporal suturectomy resulted in resolution of the clinical signs. To the author's knowledge, isolated zygomaticotemporal syno-stosis with associated temporomandibular subluxation has not been reported in the dog.