False ankylosis of the temporomandibular joint in a cat.

Progressive inability to open the mouth developed in a cat after trauma to the head. Evaluation revealed a healed depression fracture of the left zygomatic arch and normal temporomandibular joints. Surgical exploration of the fracture confirmed a false ankylosis that developed between the depression fracture and the ramus of the mandible. Treatment included excision of the central portion of the zygomatic arch and a portion of the ramus. The cat regained normal function of its mouth.