Think It’s TMJ Luxation? Most Referred Cats Had Something Else

Retrospective Analysis of Cats Referred for Suspected Temporomandibular Joint Luxation

Izzie Yi-Chin Tsai, Ya-Ting Wu

Background

Temporomandibular joint (TMJ) luxation in cats is most commonly associated with trauma and may present with clinical signs such as inability to close the mouth, mandibular deviation, drooling, and oral pain. However, due to the complexity of craniofacial anatomy and overlapping structures on radiographs, accurate diagnosis can be challenging. Computed tomography (CT) is considered superior for evaluating TMJ pathology and associated injuries. The authors observed that many cats referred with suspected TMJ luxation were ultimately diagnosed with alternative conditions. This study aimed to determine the proportion of true TMJ luxation cases among referred cats and to identify the final diagnoses in order to improve diagnostic accuracy and case management.

Methods

This retrospective study included 42 cats referred between April 2020 and February 2025 for suspected TMJ luxation as the primary complaint. Reported clinical signs included inability to close the mouth, mandibular deviation, and signs of oral pain. Medical records were reviewed for signalment, history, imaging findings, treatment, and outcomes. Diagnostic imaging included skull radiographs and, in selected cases, CT. Statistical analysis was performed using SPSS, with significance set at P < .05. Continuous variables were evaluated for normality, and categorical variables were compared using Fisher exact tests.

Results

Of the 42 cats, only 6 (14%) were diagnosed with isolated TMJ luxation. The remaining 36 cats had alternative diagnoses:

19 (45%) with end-stage periodontal disease

5 (12%) with malocclusion

4 (10%) with mandibular symphyseal separation

3 (7%) with open-mouth jaw locking from other suspected TMJ-related causes

2 (5%) with mandibular fractures

2 (5%) with no significant findings

1 (2%) with TMJ ankylosis

All confirmed TMJ luxations involved rostral displacement of the condylar process and were successfully treated with closed reduction without recurrence.

Indoor-only cats were significantly more likely to have isolated TMJ luxation compared to cats with complex traumatic conditions (P = .02). Kittens were significantly more likely to be diagnosed with malocclusion (P = .002), while adult cats were significantly more likely to have end-stage periodontal disease (P = .001). The median age for malocclusion cases was 7 months, and for periodontal disease cases was 7 years.

Limitations

Limitations include the small sample size and retrospective design, which may have resulted in incomplete records and inconsistent follow-up. Not all cats underwent CT examination, so some diagnoses were based primarily on clinical and radiographic findings. The study was conducted at a single referral hospital, potentially limiting generalizability.

Conclusions

True TMJ luxation accounted for a minority of cats referred with suspected TMJ luxation. End-stage periodontal disease was the most common final diagnosis, followed by malocclusion and other craniofacial conditions. Clinical signs such as inability to close the mouth and mandibular deviation are nonspecific and may mimic TMJ luxation. Thorough oral examination, appropriate radiographic evaluation, and advanced imaging when indicated are essential for accurate diagnosis and appropriate treatment planning.

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