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Home / Equine Research Bank / Equine Vet J / Computed tomography of the equine temporohyoid joint: Associ...
Equine veterinary journal2025; doi: 10.1111/evj.14495

Computed tomography of the equine temporohyoid joint: Association between imaging changes and potential risk factors.

Abstract: Temporohyoid osteoarthropathy (THO) is characterised by bone proliferation and cartilage ossification caused by infectious and degenerative conditions, amongst others. Objective: To describe the variable appearance of the temporohyoid joint (THJ) on computed tomography (CT) and investigate associations between CT changes and potential risk factors. Methods: Cross-sectional study. Methods: Head CT examinations were assessed. A grading system was developed for osseous proliferation (grade 0 [normal] to 3 [severe]) and tympanohyoid cartilage change (grade 0 [normal] to 3 [complete ossification]). Grades were also summed to create an overall sum grade. Ordinal logistic regression was performed to produce a multivariable model that assessed the association between THJ grade and signalment, presenting signs, CT features, and final diagnosis. Results: The horses included (n = 424) most commonly presented for dental and sinus disorders (37.7%). The most frequently observed (mode) bone grade, cartilage grade and overall grade were 2 (41.9%), 0 (52.6%) and 2 (27.0%), respectively. Bone proliferation was most common medially and caudally. Soft tissue swelling (OR 1.9, 95% CI 1.2-3.1, p < 0.05) and temporal bone fragmentation (OR 26.6, 95% CI 5.1-141.4, p < 0.05) were associated with increased bone grade. There was no correlation between increased grade and any presenting sign. Increased sum grade was significantly associated with increased age (OR per year 1.1, 95% CI 1.0-1.1, p < 0.05), Arabians (OR 4.2, 95% CI 1.3-14.0, p < 0.05) and Thoroughbreds (OR 2.9, 95% CI 1.5-5.4, p < 0.05) relative to Warmbloods. Conclusions: Following training, a single observer evaluated images. Conclusions: Moderate caudomedial osseous proliferation of the THJ is common in horses presented for unrelated disease. Cartilage mineralisation, soft tissue swelling, and temporal bone fragmentation may serve as markers of disease. Thoroughbreds and Arabians are at increased risk of greater THJ remodelling. Increased THJ change was associated with age but not otitis, suggesting THO is predominantly degenerative. Unassigned: Die Temporohyoid‐Osteoarthropatie (THO) ist durch Knochenproliferation und Verknöcherung des Knorpels gekennzeichnet, welche unter anderem durch infektiöse und degenerative Erkrankungen verursacht werden. Unassigned: Beschreibung des variablen Erscheinungsbildes des Temporohyoidgelenks (THJ) in der Computertomographie (CT) und Untersuchung von Zusammenhängen zwischen CT‐Veränderungen und möglichen Risikofaktoren. Methods: Querschnittsstudie. Methods: CT‐Untersuchungen des Kopfes wurden ausgewertet. Es wurde ein Bewertungssystem für die knöcherne Proliferation (Grad 0 [normal] bis 3 [schwerwiegend]) und die tympanohyoidale Knorpelveränderung (Grad 0 [normal] bis 3 [vollständige Verknöcherung]) entwickelt. Die Grade wurden auβerdem addiert, um einen Gesamtsummengrad zu erhalten. Es wurde eine logistische Ordinalregression durchgeführt, um ein multivariables Modell zu erstellen, das den Zusammenhang zwischen Grad des THJ und des Signalements, Vorstellungsgrund, CT‐Merkmalen und der endgültigen Diagnose beurteilte. Unassigned: Die einbezogenen Pferde (n = 424) wurden am häufigsten wegen Zahn‐ und Kieferhöhlenerkankungen vorgestellt (37,7%). Der am häufigsten beobachtete Knochengrad, Knorpelgrad und Gesamtsummengrad waren 2 (41,9%), 0 (52,6%) und 2 (27,0%). Knochenproliferationen traten am häufigsten medial und kaudal auf. Weichteilschwellungen (OR 1,9, 95% CI 1,2‐3,1, p < 0,05) und Knochenfragmentierung des Os Temporale (OR 26,6, 95% CI 5,1‐141,4, p < 0,05) waren mit einem erhöhten Knochengrad verbunden. Es gab keine Korrelation zwischen erhöhtem Grad und einem der Vorstellungsgründe. Ein erhöhter Summengrad war signifikant mit einem höherem Alter (OR pro Jahr 1,1, 95% CI 1,0‐1,1, p < 0,05), Arabern (OR 4,2, 95% CI 1,3‐14,0, p < 0,05) und Vollblütern (OR 2,9, 95% CI 1,5‐5,4, p < 0,05) im Vergleich zu Warmblütern verbunden. HAUPTEINSCHRÄNKUNGEN: Nach dem Training wurde ein einzelner Beobachter eingesetzt. Unassigned: Eine mäβige kaudomediale knöcherne Proliferation des THJ ist bei Pferden, die wegen einer nicht im Zusammenhang stehenden Krankheit vorstellig werden, häufig. Knorpelmineralisierung, Weichteilschwellung und Fragmentierung des Os Temporale können als Marker für Erkrankung dienen. Vollblüter und Araber haben ein erhöhtes Risiko für eine stärkere Umbildung des THJ. Vermehrte Veränderungen des THJ wurden mit dem Alter, nicht aber mit einer Otitis in Verbindung gebracht, was darauf hindeutet, dass die THO überwiegend degenerativ ist.
© 2025 The Author(s). Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
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Publication Date: 2025-05-05 PubMed ID: 40322953DOI: 10.1111/evj.14495Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research looked at the variables and potential risk factors of Temporohyoid osteoarthropathy (THO), a degenerative bone disease found in horses. Study was based on horse CT scans and developed a grading system to evaluate bone proliferation and joint changes. It found factors like breed and age of the horse did influence the severity of the osteoarthropathy, but there was no association between higher grading and the presenting sign of illness.

Study Overview

  • This research used a cross-sectional study model, where a group of 424 horses were sampled once and observed for potential signs and risk factors related to THO, a degenerative joint disease that can affect horses.
  • The researchers used computed tomography (CT) scans of the horse’s heads and analyzed the temporohyoid joint (THJ), a small but integral joint that connects the skull with the first vertebra and aids the horse in head movement and stability.
  • A grading system was developed for evaluating osseous (bony) proliferation and changes in tympanohyoid cartilage, ranging from normal (0) to severe (3). These grades were then summed to create an overall score for THJ changes in each horse.

Findings

  • Most horses in the study were seen for dental or sinus disorders. The most frequently observed bone grade was 2 (41.9%), indicating moderate bone changes, while the cartilage grade was most often 0 (52.6%) implying normal cartilage. The combined sum grade was most typically also 2 (27.0%).
  • Bone modifications were most often seen on the medial (towards the middle) and caudal (towards the back) aspects of the joint.
  • Increased bone grade was significantly associated with soft tissue swelling and temporal bone fragmentation. But there was no link found between an elevated grade and any presenting sign of disease in the horse at the time of the CT scan.
  • Increased overall grade was significantly associated with an increase in the age of the horse, with each additional year of age increasing the chances of a higher THJ change.
  • Certain breeds (Arabians and Thoroughbreds) were more prone to THJ remodelling compared to others.

Conclusions

  • The study concluded moderate caudomedial (rear and middle) bone proliferation of the THJ is common in horses presented for unrelated disease.
  • Cartilage mineralisation, soft tissue swelling, and temporal bone fragmentation can serve as potential markers of the disease.
  • The research suggested that THO is predominantly degenerative as its relationship to age was confirmed but there wasn’t any association with any disease signs at the time of the CT scan.

Cite This Article

APA
Dash RF, Perkins JD, Chang YM, Morgan RE. (2025). Computed tomography of the equine temporohyoid joint: Association between imaging changes and potential risk factors. Equine Vet J. https://doi.org/10.1111/evj.14495

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English

Researcher Affiliations

Dash, Rupert F
  • The Royal Veterinary College, Equine Referral Hospital, North Mymms, Hertfordshire, UK.
Perkins, Justin D
  • The Royal Veterinary College, Equine Referral Hospital, North Mymms, Hertfordshire, UK.
Chang, Yu-Mei
  • The Royal Veterinary College, Equine Referral Hospital, North Mymms, Hertfordshire, UK.
Morgan, Rhiannon E
  • IVC Evidensia UK, The Chocolate Factory, Bristol, UK.

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