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Home / Equine Research Bank / Front Vet Sci / Computed tomographic signs of hyoid apparatus disease in 165...
Frontiers in veterinary science2025; 12; 1631185; doi: 10.3389/fvets.2025.1631185

Computed tomographic signs of hyoid apparatus disease in 165 horses.

Abstract: Horses with hyoid bone disease may present with clinical symptoms such as exercise intolerance, resistance to ridden work, anorexia, or headshaking. This study aims to describe the computed tomographic (CT) signs and prevalence of hyoid disease and to evaluate their association with other CT changes of the head. Unassigned: In this study, four investigators conducted a retrospective analysis of their findings after reviewing the medical records of 200 horses that had undergone CT scans between 2009 and 2019. A total of 32 parameters were analyzed, and associations were evaluated between those parameters and the effects of age, weight, and use on the development of hyoid bone disease. Unassigned: The temporohyoid joint (THJ) exhibited the most common CT signs, with 52% of cases showing marginal exostosis of the temporal bone, 44.4% displaying osteophytes of the proximal stylohyoid, and 40.2% demonstrating reduced tympanohyoid on the examined sides. The most frequently observed CT signs at the styloceratohyoid/epiceratohyoid joint were marginal exostosis of the distal stylohyoid, identified in 29.0% of the examined sides, and osteoproliferative changes of the proximal ceratohyoid, present in 16.5% of the examined sides. CT signs of disease were rarely found at the ceratobasihyoid joint. Pathological CT signs of the ceratobasihyoid joint were associated with those of the styloceratohyoid/epiceratohyoid joint, and disease in this joint was associated with those of the THJ. The findings of the present study revealed an age-related effect on the occurrence of marginal exostosis and osseous cyst-like lesions (OCLLs) of the temporal bone, as well as on OCLLs and osteophytes of the proximal stylohyoid, and on the thickening of the THJ, and a reduction in the tympanohyoid. Age was also found to influence the incidence of the two styloceratohyoid/epiceratohyoid joint CT signs: marginal exostosis of the distal stylohyoid and osteoproliferative changes at the proximal ceratohyoid. The weight and use of the horses did not affect the occurrence of the evaluated changes. Unassigned: CT signs of disease of the hyoid apparatus are common and should be considered as part of the differential diagnosis when examining a horse with poor performance, riding complaints, or headshaking.
Copyright © 2025 Hartl, Strohmayer, Vali, Lyrakis and Kneissl.
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Publication Date: 2025-09-19 PubMed ID: 41049149PubMed Central: PMC12492637DOI: 10.3389/fvets.2025.1631185Google Scholar: Lookup
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Summary

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Overview

  • This research article investigates the prevalence and characteristics of hyoid apparatus disease in horses using computed tomography (CT) scans.
  • The study aims to identify CT signs of disease in the hyoid bones and assess how these signs correlate with age, weight, use, and other head abnormalities in horses.

Introduction to Hyoid Apparatus Disease in Horses

  • Hyoid bone disease in horses can lead to clinical symptoms such as:
    • Exercise intolerance
    • Resistance to ridden work
    • Anorexia
    • Headshaking
  • The hyoid apparatus comprises several bones and joints essential for head and throat mechanics.
  • Computed tomography (CT) allows detailed imaging to detect structural changes in these bones and joints.

Study Design and Methods

  • This was a retrospective study analyzing CT scans and medical records of 200 horses collected between 2009 and 2019.
  • Four investigators reviewed records and analyzed 32 different CT parameters related to the hyoid apparatus.
  • The study investigated associations between CT signs and factors like:
    • Age
    • Weight
    • Use (type of work the horse is engaged in)
  • Statistical evaluations were conducted to determine the correlation between parameters and disease development.

Key Findings on CT Signs of Disease

  • The temporohyoid joint (THJ) exhibited the most frequent signs of disease:
    • Marginal exostosis (bone spur) of the temporal bone in 52% of cases.
    • Osteophytes (bony outgrowths) of the proximal stylohyoid bone in 44.4% of cases.
    • Reduction in size or density of the tympanohyoid bone in 40.2% of cases.
  • At the styloceratohyoid/epiceratohyoid joint, common CT signs included:
    • Marginal exostosis on the distal stylohyoid in 29% of sides examined.
    • Osteoproliferative changes (excessive bone growth) on the proximal ceratohyoid in 16.5% of sides examined.
  • Disease signs were rare at the ceratobasihyoid joint but when present, correlated with disease signs in other joints:
    • Associations found between ceratobasihyoid and styloceratohyoid/epiceratohyoid joint disease.
    • Disease in ceratobasihyoid was also linked to temporohyoid joint disease.

Influence of Age, Weight, and Use on Disease Development

  • Age was strongly associated with the following:
    • Increased incidence of marginal exostosis and osseous cyst-like lesions (OCLLs) of the temporal bone.
    • OCLLs and osteophytes of the proximal stylohyoid bone.
    • Thickening of the temporohyoid joint and reduction of the tympanohyoid bone.
    • Marginal exostosis of the distal stylohyoid and osteoproliferative changes at the proximal ceratohyoid.
  • Weight of the horses showed no significant influence on the occurrence of hyoid apparatus disease.
  • Use or type of work performed by the horses also did not affect the development of CT changes.

Clinical Implications and Conclusion

  • CT signs of hyoid apparatus disease are common findings in horses, especially as they age.
  • Clinicians should consider hyoid bone disease when presented with horses showing:
    • Poor performance
    • Riding complaints
    • Headshaking behavior
  • This study highlights that CT imaging is a valuable diagnostic tool to detect subtle bony changes and joint disease that may not be apparent in other imaging modalities.
  • Early identification of such changes can aid in the management of equine patients with related clinical signs.

Cite This Article

APA
Hartl B, Strohmayer C, Vali Y, Lyrakis M, Kneissl SM. (2025). Computed tomographic signs of hyoid apparatus disease in 165 horses. Front Vet Sci, 12, 1631185. https://doi.org/10.3389/fvets.2025.1631185

Publication

Frontiers in veterinary science
ISSN: 2297-1769
NlmUniqueID: 101666658
Country: Switzerland
Language: English
Volume: 12
Pages: 1631185
PII: 1631185

Researcher Affiliations

Hartl, Bettina
  • Department of Biological Sciences and Pathobiology, Institute of Morphology, Vetmeduni, Austria.
Strohmayer, Carina
  • Diagnostic Imaging, Clinical Department of Small Animals and Horses, Vetmeduni, Austria.
Vali, Yasamin
  • Diagnostic Imaging, Clinical Department of Small Animals and Horses, Vetmeduni, Austria.
Lyrakis, Manolis
  • Platform for Bioinformatics and Biostatistics, Department of Biological Sciences and Pathobiology, Vetmeduni, Austria.
Kneissl, Sibylle M
  • Diagnostic Imaging, Clinical Department of Small Animals and Horses, Vetmeduni, Austria.

Conflict of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision.

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