Evaluation of microRNA expression in plasma and skeletal muscle of thoroughbred racehorses in training.
Authors: McGivney B A, Griffin M E, Gough K F, McGivney C L, Browne J A, Hill E W, Katz L M
Journal: BMC veterinary research
Summary
Circulating microRNAs (miRNAs) hold promise as non-invasive biomarkers for equine health and performance assessment, yet establishing baseline expression patterns in response to exercise remains essential before their clinical application. McGivney and colleagues profiled plasma miRNA expression in 20 Thoroughbreds in sprint training before and after exercise, whilst simultaneously examining muscle miRNA changes in a separate cohort of 11 young horses; the team also investigated haemolysis—a confounding factor known to contaminate plasma samples in horses following intense work—across resting blood samples from 12 additional animals. Exercise-induced alterations in miRNA expression were identified in both plasma and skeletal muscle, though significantly, naturally occurring haemolysis from moderate-to-intense exertion substantially interfered with accurate plasma miRNA quantification, suggesting current spectrophotometric haemolysis detection methods may be insufficient for quality control in equine samples. These findings underscore a critical technical limitation: without addressing haemolysis-related artefacts, plasma miRNA profiling cannot reliably serve as a diagnostic tool in clinical or performance settings where horses have recently been exercised. For practitioners considering miRNA testing to evaluate training responses, tissue damage, or performance capacity, awareness of these pre-analytical challenges is vital, and standardised protocols accounting for exercise-induced haemolysis will be necessary before such biomarkers transition from research into practical application.
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Practical Takeaways
- •If using plasma miRNA as a diagnostic tool in performance horses, be aware that exercise-induced haemolysis will affect results—samples must be carefully handled and haemolysis quantified to avoid false interpretation
- •Baseline miRNA expression patterns in healthy, actively training Thoroughbreds have now been documented, providing a reference for identifying abnormal responses to training or recovery
- •MiRNA profiling may help detect training-related muscle stress or overtraining syndrome, but requires standardised sampling protocols accounting for haemolysis
Key Findings
- •Circulating miRNA profiles change in response to exercise in Thoroughbred racehorses, with multiple miRNAs upregulated post-exercise
- •Haemolysis naturally occurs in horses following moderate-to-intense exercise and significantly impacts accurate plasma miRNA quantification
- •Skeletal muscle miRNA abundance differs between resting and post-exercise states in young Thoroughbreds entering sprint training
- •A panel of 179 miRNAs can be used to profile equine plasma, but haemolysis must be controlled for reliable diagnostic biomarker interpretation