Effects of repeated biopsying on muscle tissue in horses.
Authors: Lindner A, Dag S, Marti-Korff S, Quiroz-Rothe E, López Rivero J L, Drommer W
Journal: Equine veterinary journal
Summary
Repeated muscle biopsies are increasingly used in equine practice to assess performance potential, training adaptation and exertional myopathies, yet the tissue trauma from sequential sampling raises questions about reliability of results. Lindner's team examined gluteus medius samples from seven Thoroughbreds that had undergone three previous biopsies at 7-week intervals, collecting additional samples at standardised depths and sites to evaluate whether prior biopsy sites showed pathological changes affecting interpretation. Whilst 25% of samples exhibited repair responses ranging from regenerative healing to fibrotic scarring, 75% remained histologically normal, and critically, sufficient normal tissue was consistently available to measure standard muscle fibre variables without diagnostic compromise. The findings demonstrate that 7-week intervals between biopsies do not meaningfully impair assessment of muscle fibre type characteristics needed to evaluate training responses, though the study emphasises that sample location variation of just 3 cm laterally can produce substantial differences in fibre-type measurements. For practitioners utilising muscle biopsy data to guide conditioning programmes or investigate myopathies, this research validates the technique's repeatability provided sampling sites and techniques are rigorously standardised—a sobering reminder that protocol consistency matters as much as biopsy timing when tracking tissue adaptations serially.
Read the full abstract on PubMed
Practical Takeaways
- •Repeated muscle biopsies of the gluteus medius at 7-week intervals are safe and do not compromise diagnostic accuracy for assessing training response and myopathies
- •Standardisation of biopsy location, depth, and technique is critical—minor variations of 3 cm can produce significantly different results, so precise anatomical landmarks must be documented
- •While some local muscle repair occurs after biopsy, adequate normal tissue remains for reliable assessment of muscle fibre type and morphology in clinical and research settings
Key Findings
- •75% of muscle samples showed normal morphology after repeated biopsying at 7-week intervals, with 25% showing repair or scar formation
- •Sufficient normal tissue was consistently available for measuring routine muscle variables despite previous biopsy sites
- •Samples collected only 3 cm laterally apart showed large variations in muscle fibre type variables, demonstrating importance of standardised biopsy technique
- •Repeated gluteus medius biopsies at 7-week intervals do not impair evaluation of muscle fibre variables for assessing conditioning programme effectiveness