Equine veterinary journal2026; doi: 10.1002/evj.70328

Serum osteocalcin is associated with scintigraphic abnormalities in lame and clinically sound racehorses.

Tually, P
·
Blache, D
·
Meadows, J
·
Tagore, S
·
O'Callaghan, P
·
Hathway, M
·
Fulton, I
·
Currie, G

Abstract: Musculoskeletal injury is a major welfare and economic challenge in racehorses, with stress-related bone injury contributing to training interruption and catastrophic failure. Advanced imaging modalities can detect early skeletal pathology but remain limited in routine screening environments. Circulating biomarkers of bone turnover may provide complementary indicators of skeletal remodelling but require validation against objective imaging findings. Objective: Evaluate whether osteocalcin (OC) and C-terminal telopeptide of type I collagen (CTX), or the CTX/OC ratio, are associated with scintigraphic abnormalities and lameness status in racehorses and explore relationships with short-term adverse musculoskeletal outcomes. Methods: Prospective, observational case-control study. Methods: Ninety-six racehorses were enrolled, including 48 lame horses referred for scintigraphy and 48 clinically sound controls. Serum OC and CTX concentrations were measured by ELISA at the time of scintigraphic examination. Scintigraphic scans were classified as no abnormality detected (NAD), moderately positive (mPOS) or strongly positive (sPOS). Associations were assessed using non-parametric tests, logistic regression and receiver operating characteristic analysis. Clinically sound horses were followed for 28 days to record adverse musculoskeletal outcomes. Results: OC concentrations were higher in lame horses than in controls (mean difference 0.68 ng/mL, 95% CI 0.19-1.17) and differed across scintigraphic categories, with OC concentrations lower in NAD horses than in mPOS horses (mean difference 1.61 ng/mL, 95% CI 0.35-2.87). In the exploratory pooled injury analysis, higher OC concentrations were associated with musculoskeletal injury status (OR 9.75, 95% CI 2.82-49.38; AUC 0.75). In clinically sound horses, CTX and the CTX/OC ratio were not significantly associated with 28-day adverse musculoskeletal outcome. Conclusions: Short follow-up duration, limited outcome events and potential workload-related confounding at sampling. Conclusions: Serum OC concentrations were associated with lameness status and scintigraphic severity. Bone turnover markers may provide complementary biological information alongside imaging but require validation in larger longitudinal studies.

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Publication Date: 2026-09-22 PubMed ID: 42770892DOI: 10.1002/evj.70328Google Scholar: Lookup

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Summary

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Overview

This study investigated whether blood levels of bone turnover markers, specifically osteocalcin (OC) and C-terminal telopeptide of type I collagen (CTX), are linked to bone abnormalities seen on scintigraphy and to lameness in racehorses.
It also explored whether these markers could predict short-term musculoskeletal injuries, aiming to find less invasive methods to detect bone problems early in racehorses.

Background and Purpose

Musculoskeletal injuries, especially stress-related bone injuries, pose serious welfare issues and economic challenges for racehorses by causing interruptions in training or catastrophic breakdowns.
Advanced imaging, like scintigraphy, can detect early bone pathology but is not always practical for routine screening due to cost and accessibility.
Blood biomarkers that reflect bone remodeling could potentially serve as complementary or screening tools, but their clinical relevance needs validation comparing to imaging results.
The study focused on two blood markers: osteocalcin (OC), indicative of bone formation, and CTX, a marker of bone resorption, as well as the ratio between them.

Study Design and Methods

This was a prospective, observational case-control study involving 96 Thoroughbred racehorses.
The study group consisted of 48 lame horses referred for scintigraphic imaging and 48 clinically sound controls matched for comparison.
At the time of scintigraphy, serum OC and CTX concentrations were measured using ELISA tests.
Scintigraphic scans were classified into three categories based on detected bone abnormalities:
- No abnormality detected (NAD)
- Moderately positive (mPOS)
- Strongly positive (sPOS)
Statistical methods included non-parametric tests to assess differences, logistic regression to estimate odds ratios, and receiver operating characteristic (ROC) analysis to evaluate predictive performance.
Clinically sound horses were monitored for 28 days post-examination to observe any adverse musculoskeletal outcomes.

Key Findings

Serum osteocalcin concentrations were significantly higher in lame horses compared to the clinically sound controls.
OC levels differed between scintigraphic groups, being lowest in horses with no detected abnormalities and increased with more severe scintigraphic abnormalities (mPOS > NAD).
Higher OC concentrations were strongly associated with an increased likelihood of musculoskeletal injury when considering pooled data (both lame and control horses), with an odds ratio around 9.75 and acceptable predictive accuracy (AUC 0.75).
CTX levels and the ratio of CTX to OC did not show a significant association with short-term (28-day) adverse musculoskeletal outcomes in clinically sound horses.

Conclusions and Implications

Serum osteocalcin appears to be a promising biomarker reflective of bone turnover changes linked with both lameness and bone abnormalities detected by scintigraphy.
Bone turnover markers like OC may add valuable biological information alongside imaging findings, potentially aiding early detection of bone pathology in racehorses.
The lack of association of CTX and CTX/OC ratio with short-term injury risk suggests these markers may be less useful in predicting imminent musculoskeletal problems.
Limitations include:
- Short duration of follow-up (28 days) for detecting adverse outcomes in sound horses.
- Relatively small number of injury events, affecting statistical power.
- Potential confounding due to differing workloads or training status at the time of sampling.
Future research with larger longitudinal studies is necessary to validate these findings and establish clinical utility for routine monitoring and early injury detection.

Cite This Article

APA

Tually P, Blache D, Meadows J, Tagore S, O'Callaghan P, Hathway M, Fulton I, Currie G. (2026). Serum osteocalcin is associated with scintigraphic abnormalities in lame and clinically sound racehorses. Equine Vet J. https://doi.org/10.1002/evj.70328

Publication

Equine veterinary journal

ISSN: 2042-3306

NlmUniqueID: 0173320

Country: United States

Language: English

Researcher Affiliations

Tually, Peter

Department of Nuclear Medicine, TeleMedVET, Ascot, Western Australia, Australia.
School of Dentistry and Medical Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia.

Blache, Dominique

School of Agriculture and Environment, University of Western Australia, Perth, Western Australia, Australia.

Meadows, Jack

Department of Nuclear Medicine, TeleMedVET, Ascot, Western Australia, Australia.

Tagore, Shiphrah

Department of Nuclear Medicine, TeleMedVET, Ascot, Western Australia, Australia.
School of Dentistry and Medical Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia.

O'Callaghan, Paul

Perth Equine Hospital, Ascot, Western Australia, Australia.

Hathway, Matilda

Department of Nuclear Medicine, TeleMedVET, Ascot, Western Australia, Australia.
School of Veterinary Nursing, AVT, Ascot, Western Australia, Australia.

Fulton, Ian

Fulton Equine Consulting, Miners Rest, Victoria, Australia.

Currie, Geoffrey

School of Dentistry and Medical Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia.

Grant Funding

C001840 / Racing and Wagering Western Australia

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