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Animals : an open access journal from MDPI2026; 16(6); 973; doi: 10.3390/ani16060973

Objective, Longitudinal Computed Tomographic Evaluation of the Metacarpal Condyles in Non-Lame Thoroughbred Racehorses.

Abstract: There are limited data on sequential computed tomographic (CT) evaluation and objective CT assessment of the metacarpal condyles in Thoroughbred racehorses. This longitudinal study aimed to document changes in attenuation of the metacarpal condyles during the first two years of training and racing. Fan-beam CT examination of the metacarpophalangeal regions was performed on 40 non-lame Thoroughbred yearlings, and repeated four more times, approximately six months apart. Mean Hounsfield Unit (HU) measurements were obtained on sagittal reconstructions of the dorsal and palmar halves of the medial and lateral condyles and parasagittal grooves. One-way ANOVA with a post hoc Tukey's Test was used to investigate differences between mean HU values over time at the different regions of interest. Multivariable mixed-effects linear regression models assessed the association between dorsal and palmar HU and potential explanatory variables. Mean HU increased significantly with training, especially during the first six months, with a maximal sequential mean increase found in the medial parasagittal groove (119.8 [95% confidence interval 85.3, 154.30], < 0.001). Dorsal regions had higher HU than palmar regions, with the highest HU recorded in the dorsal aspect of the medial condyle at time 3 (mean HU 1120.1 ± 63.4). Condyles had higher HU than parasagittal grooves ( < 0.001), the palmar half of the right condyles had higher HU than the left ( = 0.045) and the dorsal aspect of the medial condyle had higher HU than the lateral ( < 0.001). An increasing number of race starts and higher body weight:height ratio were associated with higher HU ( < 0.001). The main limitation was the loss of horses to follow-up as the study progressed. In conclusion, density of most regions of the metacarpal condyles increased with time spent in training, reflecting adaption to racehorse training.
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Publication Date: 2026-03-20 PubMed ID: 41897950PubMed Central: PMC13023280DOI: 10.3390/ani16060973Google 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.

Research Overview

  • This study longitudinally assessed changes in bone density of the metacarpal condyles in non-lame Thoroughbred racehorses during their first two years of training and racing using computed tomography (CT).
  • The aim was to document how the density of specific regions in the metacarpal condyles changes over time as horses undergo race training.

Introduction and Background

  • The metacarpal condyles are important weight-bearing structures in horses’ legs, particularly relevant for racehorses due to high impacts during racing.
  • Previous data on CT evaluation of these bone regions over time, especially objectively analyzed in Thoroughbred racehorses, has been limited.
  • Understanding changes in bone density can give insight into how bones adapt to training stresses and help monitor early signs of injury risk or fatigue.

Study Design and Methodology

  • A longitudinal study was conducted involving 40 non-lame Thoroughbred yearling horses entering racing training.
  • Five CT scans of the metacarpophalangeal (fetlock) joints were performed on each horse approximately every six months over two years.
  • CT scans used fan-beam technology and analyzed sagittal reconstructions focusing on four regions: dorsal and palmar halves of medial and lateral condyles, plus medial and lateral parasagittal grooves.
  • Bone density was quantified using mean Hounsfield Units (HU), a standard CT measurement reflecting tissue density.
  • Data analysis involved:
    • One-way ANOVA with Tukey’s post hoc test to evaluate HU differences over time in different regions.
    • Multivariable mixed-effects linear regression to examine associations of HU values with variables such as number of race starts and body conformation metrics.

Key Findings

  • Significant increases in mean HU values were observed over time, indicating increasing bone density during training—with the largest increase in the medial parasagittal groove (mean increase of approx. 120 HU).
  • Dorsal regions consistently showed higher HU (greater density) than palmar regions.
  • The dorsal aspect of the medial condyle exhibited the highest density at the mid-point of the study (time 3), with mean HU over 1120.
  • Bone density in condyles was greater than in parasagittal grooves.
  • There was a side-to-side difference: the palmar half of right condyles was denser than the left (p=0.045).
  • The medial condyle was denser than the lateral condyle (p<0.001), reflecting anatomical or biomechanical loading differences.
  • Regression models showed that more race starts and a higher body weight-to-height ratio were linked to greater bone density.

Interpretation and Implications

  • The progressive increase in metacarpal condyle density indicates physiological adaptation of bone to the demands of early race training.
  • These density changes likely reflect bone remodeling in response to cyclical loading, enhancing structural strength of critical joint areas.
  • Understanding normal patterns of bone density adaptation can help veterinarians and trainers monitor bone health and potentially predict injury risks.
  • Side-to-side differences might inform about asymmetrical loading patterns in training or race gait mechanics.
  • Bone density metrics provided by CT are objective and can serve as biomarkers for monitoring skeletal adaptation or early pathology.

Limitations

  • There was attrition over time, as some horses were lost to follow-up, possibly due to retirement, injury, or other reasons—this could affect the longitudinal analyses.
  • The study only included non-lame horses, limiting direct conclusions about pathological bone changes or injury development.
  • Correlation with clinical outcomes or detailed training regimens was not deeply explored, which could provide further insight.

Conclusion

  • The study provides the first detailed, sequential CT evaluation documenting increasing bone density in the metacarpal condyles of Thoroughbred racehorses during early training.
  • The findings support that bone adapts by increasing mineralization in response to race training load, reflecting normal physiological remodeling.
  • These findings enhance understanding of skeletal adaptations in athletic horses and provide a baseline for future studies on bone health and injury prevention in racehorses.

Cite This Article

APA
Putnoki V, Pollard D, Dyson S, Boros K, Nagy A. (2026). Objective, Longitudinal Computed Tomographic Evaluation of the Metacarpal Condyles in Non-Lame Thoroughbred Racehorses. Animals (Basel), 16(6), 973. https://doi.org/10.3390/ani16060973

Publication

Animals : an open access journal from MDPI
ISSN: 2076-2615
NlmUniqueID: 101635614
Country: Switzerland
Language: English
Volume: 16
Issue: 6
PII: 973

Researcher Affiliations

Putnoki, Vivien
  • Department and Clinic of Equine Medicine, University of Veterinary Medicine Budapest, Dóra Major, 2225 Üllő, Hungary.
Pollard, Danica
  • Independent Researcher, The Rodhams, Rodham Road, Wisbech PE14 9NU, UK.
Dyson, Sue
  • Independent Researcher, The Cottage, Church Road, Market Weston, Diss IP22 2NX, UK.
Boros, Koppány
  • Department and Clinic of Equine Medicine, University of Veterinary Medicine Budapest, Dóra Major, 2225 Üllő, Hungary.
Nagy, Annamaria
  • Department and Clinic of Equine Medicine, University of Veterinary Medicine Budapest, Dóra Major, 2225 Üllő, Hungary.

Grant Funding

  • FK 138825 / Ministry of Innovation and Technology of Hungary from the National Research, Development and Innovation Fund

Conflict of Interest Statement

The authors declare no conflicts of interest.

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