An approximately 1.5-year-old, 3.7kg, intact male crossbreed cat was referred due to the inability to open its mouth, and soft tissue swelling around the intermandibular region. Both lesions were present since the stray cat was adopted 1 year ago, but the cause was not determined. The cat was fed exclusively with liquidized food. Previous treatments using forced stretching of the jaw, corticosteroid therapy, and periodic drainage of the soft tissue swelling were unsuccessful. Based on the physical and radiographic examinations, left temporomandibular joint ankylosis and cervical salivary mucocele were diagnosed. Under general anesthesia, the lateral aspect of the condyloid process of the left mandible was removed with roungers, and forcibly opened of the jaw was used. This enabled to open the mouth, but in an inferior degree to normal and without changing the malocclusion. The salivary mucocele was treated by right mandibular and sublingual gland resection, and drainage of the mucocele. A few days after surgery the cat was capable to clean itself and to eat softened canned food without discomfort. Two months later the cat died after being hit by a car. Post-mortem examination of the head confirmed the clinical findings.

Temporomandibular ankylosis is not common. True ankylosis involves intracapsular structures and false is caused by extracapsular lesions, as observed in this case. In general, it is associated with trauma, inflammation, tumors, and developmental conditions. The best results are obtained with procedures such as condylectomy, partial zygomatic arch resection, coronoidectomy, and resection of proliferative bone. In this case unilateral removal of the lateral aspect of the condyloid process was effective in reestablishing normal function. However, the malocclusion could not be improved. Other authors observed the same.