Computed tomography of the equine temporohyoid joint: Association between imaging changes and potential risk factors.
Authors: Dash, Perkins, Chang, Morgan
Journal: Equine veterinary journal
Summary
# Editorial Summary Temporohyoid osteoarthropathy (THO) represents a significant source of morbidity in equine patients, yet substantial uncertainty remains regarding which imaging findings indicate clinically significant disease versus incidental change. Dash and colleagues examined CT scans from 424 horses to characterise temporohyoid joint (THJ) pathology and identify risk factors, developing a standardised grading system for osseous proliferation (0–3) and tympanohyoid cartilage mineralisation (0–3). Moderate caudomedial bone proliferation proved remarkably common—present in 41.9% of horses at grade 2—regardless of presenting complaint, with most horses (52.6%) showing no cartilage ossification. The analysis revealed that temporal bone fragmentation carried the strongest association with advanced bone grade (odds ratio 26.6), whilst soft tissue swelling also significantly predicted increased bony change; notably, however, no correlation existed between THJ grades and clinical signs of otitis or neurological disease. Age and breed disposition emerged as important factors, with Arabians and Thoroughbreds showing substantially greater THJ remodelling than Warmbloods (OR 4.2 and 2.9 respectively), and risk increasing by 1.1 per year of age. These findings suggest that whilst moderate THJ changes are developmentally common, cartilage mineralisation, soft tissue swelling, and temporal bone fragmentation may serve as markers of pathologically significant disease warranting clinical investigation, and that breed predisposition warrants consideration during diagnostic and prognostic discussions with owners.
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Practical Takeaways
- •Moderate temporohyoid joint changes are incidental findings in many horses and may not cause clinical signs—imaging changes alone should not drive treatment decisions
- •Temporal bone fragmentation and soft tissue swelling are red flags on CT that warrant closer monitoring and may indicate more active disease
- •Breed and age influence THJ remodeling risk; older Arabians and Thoroughbreds should be monitored more carefully if THJ changes are detected
Key Findings
- •Moderate caudomedial bone proliferation (grade 2) was the most common finding (41.9%), present in horses with unrelated presenting complaints
- •Soft tissue swelling (OR 1.9) and temporal bone fragmentation (OR 26.6) were significantly associated with increased bone grade
- •Arabians (OR 4.2) and Thoroughbreds (OR 2.9) showed significantly greater THJ remodeling compared to Warmbloods; increased grade was associated with age (OR 1.1 per year)
- •No correlation was found between THJ grade and presenting signs including otitis, suggesting THO is predominantly degenerative rather than infectious in origin