Open-mouth jaw locking in a 5-year-old Persian cat: a case report

Open-mouth jaw locking is an uncommon condition in feline patients. A 5-year-old neutered male Persian cat was evaluated for an acute inability to close its mouth and ptyalism. The general physical examination was unremarkable. A complete oral examination revealed a reduced vertical range of motion, as well as an asymmetric malocclusion with severe displacement of the mandibles to the left. Advanced diagnostic imaging included computed tomography (CT), which revealed a typical brachycephalic conformation, skeletal malocclusion and a bilateral temporomandibular joint (TMJ) subluxation, with the left coronoid process of the mandible abnormally positioned ventrolateral to the zygomatic arch. The open-mouth jaw locking was manually reduced and resolved. Once the coronoid process was repositioned, a second CT scan was performed and confirmed complete reduction of the TMJ subluxation. Supportive treatment with meloxicam was administered and a loose-fitting tape muzzle and Elizabethan collar were applied for two weeks. There was no recurrence of open-mouth jaw locking at long-term follow-up. This case report highlights the relevance of CT imaging and 3-dimensional reconstruction in the diagnosis of this unusual condition.