Recombinant equine growth hormone does not affect the in vitro biomechanical properties of equine superficial digital flexor tendon.
Authors: Dowling Bradley A, Dart Andrew J, Hodgson David R, Rose Reuben J, Walsh William R
Journal: Veterinary surgery : VS
Summary
# Editorial Summary Growth hormone supplementation has long interested equine practitioners as a potential means of enhancing tendon quality and reducing injury risk, yet this 2002 study challenges that premise by demonstrating that recombinant equine growth hormone (rEGH) administration produces no measurable improvement in tendon biomechanics. Dowling and colleagues treated six adult Standardbred horses with rEGH (escalating from 10 to 20 micrograms per kilogram daily) over six weeks, whilst three control horses received saline injections, then subjected harvested superficial digital flexor tendons from both groups to uniaxial tensile testing to evaluate mechanical properties including stiffness, load to failure, yield stress and strain. No statistically significant differences emerged between the treated and control cohorts across any biomechanical parameter measured—a finding that held despite documented systemic effects of growth hormone treatment. For practitioners considering rEGH as part of a conditioning or injury-prevention protocol, this evidence suggests that any benefits must operate through mechanisms other than direct structural improvement of tendon material properties, warranting caution about overstating the role of growth hormone in enhancing intrinsic tendon strength in mature horses.
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Practical Takeaways
- •Growth hormone supplementation does not improve the structural strength or biomechanical properties of healthy tendons in adult horses, so it is not a viable strategy for enhancing tendon quality in performance animals
- •This negative result suggests any potential benefit of rEGH in horses must be sought in other tissues or conditions, not in direct tendon strengthening
- •Clinicians should not expect rEGH to prevent tendon injury through biomechanical enhancement of normal tissue
Key Findings
- •Recombinant equine growth hormone (rEGH) at 10-20 microg/kg/day for 6 weeks produced no significant changes in SDFT cross-sectional area, maximal load at failure, or tensile properties
- •No differences were found in stiffness, yield load, or ultimate/yield tensile strain and stress between rEGH-treated and control tendons
- •In vitro biomechanical testing found no modulation of SDFT properties by rEGH administration in adult Standardbred horses