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Research article - Peer-reviewed, 2019

Effect of circadian rhythm, age, training and acute lameness on serum concentrations of cartilage oligomeric matrix protein (COMP) neo-epitope in horses

Ekman, S.; Skioldebrand, E.; Lindahl, A.; Ruetschi, U.; Jansson, A.; Bjorkman, K.; Abrahamsson-Aurell, K.; Bjornsdottir, S.; Lofgren, M.; Hulten, L. Mattsson


Background Molecular serum markers that can identify early reversible osteoarthritis (OA) in horses are lacking. Objectives We studied serum concentrations of a novel cartilage oligomeric matrix protein (COMP) neo-epitope in horses subjected to short-term exercise and with acute lameness. The effects of circadian rhythm and age were also evaluated. Study design Longitudinal studies in healthy horses and cross-sectional comparison of lame and non-lame horses. Methods Sera were collected from five horses before and after short-term interval exercise and during full-day box rest. Sera from 32 acutely lame horses were used to evaluate age-related effects. Independent samples from control horses (n = 41) and horses with acute lameness (n = 71) were included. COMP neo-epitope concentrations were analysed using custom-developed inhibition ELISAs validated for equine serum. The presence of COMP neo-epitope was delineated in healthy and osteoarthritic articular cartilage with immunohistochemistry. Results COMP neo-epitope concentrations decreased after speed training but returned to baseline levels post-exercise. No correlations between age and serum COMP neo-epitope concentrations were found (r = 0.0013). The mean (+/- s.d.) serum concentration of COMP neo-epitope in independent samples from non-lame horses was 0.84 +/- 0.38 mu g/mL, and for lame horses was 5.24 +/- 1.83 mu g/mL (P<0.001). Antibodies against COMP neo-epitope did not stain normal articular cartilage, but intracytoplasmic staining was found in superficial chondrocytes of mild OA cartilage and in the extracellular matrix of moderately osteoarthritic cartilage. Main limitations ELISA was based on polyclonal antisera rather than a monoclonal antibody. There is a sex and breed bias within the groups of horses, also it could have been of value to include horses with septic arthritis and tendonitis and investigated joint differences. Conclusions This COMP neo-epitope can be measured in sera, and results indicate that it could be a biomarker for pathologic fragmentation of cartilage in connection with acute joint lameness.


horse; COMP neo-epitope; biomarker; lameness; serum; training; circadian

Published in

Equine Veterinary Journal
2019, volume: 51, number: 5, pages: 674-680

Authors' information

Björkman, Kristina
Swedish University of Agricultural Sciences, Department of Biomedical Science and Veterinary Public Health
Löfgren, Maria
Swedish University of Agricultural Sciences, Department of Biomedical Science and Veterinary Public Health
Lindahl, A
University of Gothenburg
Rüetschi, U.
University of Gothenburg
Swedish University of Agricultural Sciences, Department of Anatomy, Physiology and Biochemistry (AFB)
Abrahamsson-Aurell, K.
Halland Animal Hospital
Björnsdottir, S.
Agricultural University of Iceland (LBHI)
Matsson Hulten, L.
University of Gothenburg

UKÄ Subject classification

Clinical Science

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