Navicular Syndrome-related changes to collagen proportion of different cross-sections of the flexor tendons in equine distal forelimb.
Authors: Salinas, Lira-Velásquez, Bongiorno, Sandoval
Journal: Research in veterinary science
Summary
# Editorial Summary: Collagen Changes in Navicular Syndrome-Affected Tendons Navicular syndrome represents a significant source of chronic lameness in equine forelimbs, yet the underlying pathophysiological changes in the associated soft tissues remain incompletely understood. Salinas and colleagues examined collagen organisation in the superficial and deep digital flexor tendons from 60 equine forelimbs, comparing histological cross-sections between clinically sound horses and those with navicular syndrome diagnosed via lameness examination, diagnostic analgesia and radiological findings. The most striking discovery was at the deep digital flexor tendon insertion on the distal phalanx: affected horses demonstrated markedly reduced aligned collagen (12.2% versus 21.2% in sound limbs) and correspondingly increased disorganised collagen (25.1% versus 21.8%), with both differences reaching statistical significance. These findings suggest that navicular syndrome involves not merely inflammation or degeneration, but a fundamental structural reorganisation of the extracellular matrix characterised by loss of collagen fibre alignment. For practitioners, this research highlights that tendons in navicular cases undergo measurable compositional changes that may compromise their biomechanical function and regenerative capacity, potentially informing how we approach rehabilitation timelines, exercise prescription and the rationale for interventions targeting collagen remodelling such as platelet-rich plasma or stem cell therapies in these cases.
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Practical Takeaways
- •Navicular syndrome involves measurable structural changes in flexor tendon collagen organization, suggesting this is a multifactorial tissue condition beyond just bony changes
- •The distal phalanx insertion site of the deep digital flexor tendon appears to be a critical area affected in navicular syndrome, relevant for treatment targeting and prognosis
- •Increased disorganized collagen in affected tendons may compromise mechanical function and healing capacity, supporting the need for rehabilitation protocols that address tendon quality alongside lameness management
Key Findings
- •Horses with navicular syndrome showed significantly decreased aligned collagen in the DDFT insertion (12.2% vs 21.2%, p=0.0026)
- •Horses with navicular syndrome showed significantly increased non-aligned collagen in the DDFT insertion (25.1% vs 21.8%, p=0.0241)
- •Collagen proportion differences were most pronounced at the DDFT insertion in the distal phalanx
- •Flexor tendons in navicular syndrome cases display altered collagen organization in the extracellular matrix