Introduction Disorders of the temporomandibular joint (TMJ) in dogs are under-recognized and often misdiagnosed due to complex anatomy, variable clinical presentation, and limitations of conventional imaging.

TMJ pathology may involve osseous, cartilaginous, synovial, and periarticular soft-tissue structures, frequently in combination. Accurate diagnosis is essential, as treatment decisions and prognosis differ substantially between degenerative, inflammatory, infectious, traumatic, and proliferative TMJ conditions. Computed tomography (CT) and cone beam CT (CBCT) have become the imaging modalities of choice for evaluation of the oromaxillofacial region in dogs and cats, providing high-resolution assessment of osseous structures.

However, CT is inherently limited to structural imaging and offers little insight into metabolic activity, synovial inflammation, or early cartilage disease. Magnetic resonance imaging (MRI) is superior for soft-tissue and intra-articular evaluation but remains limited in availability and spatial resolution for small joint imaging in veterinary patients. Recent advances in functional imaging, specifically positron emission tomography (PET) combined with CT, as well as minimally invasive TMJ arthroscopy, offer new opportunities for earlier detection, refined characterization, and improved understanding of TMJ disease.

Computed Tomography and Cone Beam CT
CT and CBCT remain the cornerstone of TMJ imaging in dogs. These modalities provide excellent visualization of the mandibular head, condylar process, mandibular fossa, and surrounding osseous structures. CT is particularly valuable for identifying fractures, osteoarthritis, ankylosis, and osseous remodeling. However, CT findings often lag behind clinical disease, particularly in early inflammatory or degenerative conditions, and do not reliably reflect disease activity.

Magnetic Resonance Imaging
MRI allows assessment of soft tissue structures, including the articular disc, synovium, joint effusion, and periarticular muscles. MRI is especially useful in cases of suspected internal derangement (in people), septic arthritis, or myopathic pain syndromes. Despite its advantages, MRI is not routinely available in many veterinary settings and may be limited by motion artifacts and spatial resolution when evaluating small TMJ structures.

TMJ Arthroscopy
TMJ arthroscopy, as developed and described in veterinary patients, provides direct visualization of the synovial cavity, articular cartilage, disc attachments, and inflammatory changes not detectable on imaging alone. Arthroscopy allows for real-time assessment of synovitis, cartilage fibrillation, intra-articular adhesions, and early degenerative disease. In addition to its diagnostic value, TMJ arthroscopy permits targeted interventions such as lavage, synovial biopsy, adhesiolysis, and guided therapeutic injections. Arthroscopy has been shown to enhance diagnostic accuracy, refine prognostication, and guide decision-making in complex TMJ disorders, particularly when imaging findings are equivocal or discordant with clinical signs.

Dual-Tracer PET-CT in Oromaxillofacial and TMJ Disease
Positron emission tomography is most used in veterinary medicine for oncologic staging; however, PET imaging is not specific for neoplasia and can identify areas of increased metabolic and osteoblastic activity associated with inflammation and infection. Combining PET with CT enables precise anatomical localization of metabolically active disease.

Clinical Implications and Future Directions
Advanced imaging and arthroscopy are reshaping the diagnostic paradigm for TMJ disorders in dogs. Integration of CT, MRI, TMJ arthroscopy, and functional imaging such as PET-CT allows for comprehensive structural and metabolic assessment of the joint and surrounding tissues. These modalities facilitate earlier diagnosis, improved disease characterization, and more targeted therapeutic strategies. Future work will focus on refining imaging protocols, validating outcome-based indications for PET-CT, and expanding the clinical application of TMJ arthroscopy. Collectively, these technologies advance the standard of care for veterinary patients with TMJ disease and strengthen translational parallels with human TMJ diagnostics.

References
1. Arzi B, Cissell DD, Verstraete FJ, Kass PH, DuRaine GD, Athanasiou KA. Computed tomographic findings in dogs and cats with temporomandibular joint disorders: 58 cases (2006-2011). J Am Vet Med Assoc. 2013;242(1):69-75.
2. De Paolo MH, Arzi B, Pollard RE, Kass PH, Verstraete FJM. Craniomaxillofacial Trauma in Dogs-Part II: Association Between Fracture Location, Morphology and Etiology. Front Vet Sci. 2020;7:242.
3. De Paolo MH, Arzi B, Pollard RE, Kass PH, Verstraete FJM. Craniomaxillofacial Trauma in Dogs-Part I: Fracture Location, Morphology and Etiology. Front Vet Sci. 2020;7:241.
4. McKay RM, Vapniarsky N, Hatcher D, Carr N, Chen S, Verstraete FJM, et al. The Diagnostic Yield of Cone-Beam Computed Tomography for Degenerative Changes of the Temporomandibular Joint in Dogs. Front Vet Sci. 2021;8:720641.
5. Quadflieg I, Ordobazari J, Lupke M, Freise F, Volk HA, Metje B. Development and Validation of an Examination Protocol for Arthroscopic Evaluation of the Temporomandibular Joint in Dogs. Animals (Basel). 2024;14(9).
6. Arzi B, Goldschmidt S, Chrostek E, Duong MV, Filliquist B, Chou PY. A needle arthroscopy approach to the temporomandibular joints in dogs. Front Vet Sci. 2026;13:1760965.