Biochemical differences between distal limb extensor and flexor tendons among equine breeds selected for racing and sport.
Authors: Verkade M E, Hazeleger E, van de Lest C H A, Back W
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary Selective breeding for specific athletic disciplines has likely shaped the biochemical composition of equine tendons, yet direct comparisons between racing and sport breeds remained unexplored until this 2020 investigation. Verkade and colleagues conducted a detailed biochemical analysis of the superficial digital flexor tendon (SDFT) and common digital extensor tendon (CDET) harvested from middle-aged Thoroughbreds (n = 8), Warmbloods (n = 12) and Friesians (n = 12), quantifying water content, collagen concentration, glycosaminoglycan levels, crosslink density and cellular content across these breeds. Sport horses demonstrated significantly higher water percentage, lower collagen and glycosaminoglycan concentrations, lower DNA content, but substantially higher collagen crosslink concentrations compared to Thoroughbreds (P < 0.05)—biochemical signatures that favour elasticity over absolute tensile strength. The findings suggest Thoroughbreds rely on greater fibrillar collagen volume for tendon strength to withstand high-speed galloping stresses, whilst Friesians and Warmbloods have evolved more elastic, less stiff tendons suited to the varied movement demands of dressage and jumping. For practitioners, these breed-specific tendon properties have significant implications for injury prevention strategies, rehabilitation protocols and training intensity recommendations, particularly regarding how different breeds tolerate and recover from tendon strain.
Read the full abstract on PubMed
Practical Takeaways
- •Different horse breeds have evolved structurally different tendons reflecting their discipline demands—racing breeds have stiffer, stronger tendons while sport breeds have more elastic tendons, which may influence injury prevention and rehabilitation strategies
- •Breed-specific tendon properties should be considered when assessing tendon injury risk and designing conditioning programs, as Thoroughbreds and sport horses may respond differently to training loads
- •Understanding that sports horses naturally have more elastic tendons may explain differences in how these breeds tolerate various athletic demands and inform preventative care approaches
Key Findings
- •Sports horse tendons (Friesian, Warmblood) had significantly higher water percentage, lower collagen/glycosaminoglycan content, and higher crosslink concentrations compared to Thoroughbreds (P < 0.05)
- •DNA content was significantly lower in sports horses than racehorses (P < 0.05)
- •Thoroughbred tendons relied primarily on extra fibrillar collagen for strength, while sports horse tendons relied on crosslink collagen support for elasticity
- •Biochemical tendon properties correlate with breed selection for locomotor performance: racing breeds have stronger tendons, sporting breeds have more elastic tendons