Effect of circadian rhythm, age, training and acute lameness on serum concentrations of cartilage oligomeric matrix protein (COMP) neo-epitope in horses.
Authors: Ekman S, Lindahl A, Rüetschi U, Jansson A, Björkman K, Abrahamsson-Aurell K, Björnsdóttir S, Löfgren M, Hultén L Mattsson, Skiöldebrand E
Journal: Equine veterinary journal
Summary
# Editorial Summary Early identification of cartilage degradation in horses remains a significant clinical challenge, particularly given the difficulty in detecting reversible osteoarthritis before substantial joint damage occurs. This 2019 study investigated a novel cartilage oligomeric matrix protein (COMP) neo-epitope as a potential serum biomarker, examining its behaviour across different physiological states—including acute exercise, circadian variation and lameness—in healthy and lame horses using validated inhibition ELISAs and immunohistochemical analysis. The researchers found that COMP neo-epitope concentrations dropped temporarily following intense interval training but normalised within the post-exercise period, showed no age-related correlation, and most notably, demonstrated a sixfold elevation in acutely lame horses (mean 5.24 μg/mL) compared with non-lame controls (0.84 μg/mL; P<0.001); immunohistochemistry revealed the neo-epitope only in chondrocytes of mild to moderate osteoarthritic cartilage, not in healthy tissue. These findings suggest COMP neo-epitope could serve as a serum-based indicator of pathological cartilage fragmentation associated with joint disease, potentially offering equine practitioners an objective laboratory marker to support earlier clinical intervention, though the authors note limitations including the reliance on polyclonal rather than monoclonal antibodies and a need for further validation across different joint types and concurrent conditions such as septic arthritis.
Read the full abstract on PubMed
Practical Takeaways
- •A serum COMP neo-epitope biomarker may help identify early cartilage damage in lame horses, potentially enabling earlier intervention before irreversible joint changes occur
- •The biomarker's transient response to exercise suggests it reflects acute cartilage stress, making it potentially useful for post-exercise lameness evaluation and training load assessment
- •This test could complement traditional lameness diagnosis and imaging in horses presenting with joint-related lameness, though further validation across different joint types and conditions is needed
Key Findings
- •COMP neo-epitope concentrations were 6.2-fold higher in acutely lame horses (5.24 ± 1.83 µg/mL) compared to non-lame control horses (0.84 ± 0.38 µg/mL, P<0.001)
- •COMP neo-epitope concentrations decreased after speed training but returned to baseline post-exercise, indicating transient response to acute exercise stress
- •No age-related correlation with serum COMP neo-epitope concentrations was found (r = 0.0013) in horses aged 2–25 years
- •Immunohistochemistry confirmed COMP neo-epitope presence in superficial chondrocytes of mild OA and extracellular matrix of moderate OA, but not in normal cartilage