Dislocation of the jaw (TMJ luxation)

Temporomandibular joint luxation (TMJ luxation) is dislocation of the joint connecting the upper and lower jaws. It is an uncommon traumatic injury that is more common in cats and small dogs than in larger dogs. We have occasionally seen this injury in indoor only cats with no known trauma. In those cases likely something unwitnessed happened inside the home, because, well…. Cats!

When this happens, the joint between the upper and lower jaw becomes dislocated, similar to a dislocated hip or shoulder injury. Most of the time, the injury can be manually reduced under anesthesia by a veterinarian with a good understanding of trauma to the head and face. This injury occurs in the back of the head but can cause inability to close the mouth due to shifting of the jaw to one side or the other.

The difficulty in diagnosis lies in the fact that that the same shift can be caused by a jaw fracture, and both injuries require advanced imaging to adequately diagnose. My opinion is that x-rays of the full skull are of no value in looking at traumatic injuries of the head.

Occasionally, surgery may be required to either replace the joint or to modify it to relieve the trauma, especially if the injury has been longstanding.