The cross-sectional area changes in digital flexor tendons and suspensory ligament in foals by ultrasonographic examination.
Authors: Korosue K, Endo Y, Murase H, Ishimaru M, Nambo Y, Sato F
Journal: Equine veterinary journal
Summary
# Editorial Summary Flexural deformities in growing foals are thought to arise from disproportionate development of the musculotendinous units in the limb, yet little longitudinal data exists documenting how individual digital flexor tendons and supporting ligaments grow relative to one another during the critical first two years of life. Korosue and colleagues performed serial ultrasonographic measurements of the superficial digital flexor tendon, deep digital flexor tendon, accessory ligament of the deep digital flexor, and suspensory ligament in seven Thoroughbred foals from birth to 24 months, tracking cross-sectional area changes at monthly intervals in both the suspensory origin region and suspensory body region. The suspensory ligament demonstrated notably greater cross-sectional area than other structures at birth—a dominance persisting to two months in the origin region and five months in the body region—whilst the deep digital flexor showed the greatest rate of expansion between two and five months, and the superficial digital flexor exhibited its peak growth phase between ten and fifteen months. These findings suggest that the soft tissue structures supporting the metacarpophalangeal region undergo asynchronous development driven by their individual functional demands, indicating that flexural deformities may emerge when growth velocity mismatches prevent adequate accommodation of limb biomechanics during specific developmental windows. For practitioners managing young stock, this heterogeneous growth pattern reinforces the importance of monitoring foals during the ten- to fifteen-month period when superficial digital flexor development accelerates, and supports early intervention strategies targeting structures showing disproportionate development relative to their peers.
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Practical Takeaways
- •Different tendons and ligaments in foals undergo growth spurts at different ages; understanding this timeline may help identify when foals are most vulnerable to flexural deformity development
- •Ultrasonographic baseline measurements of tendon and ligament cross-sectional area in healthy foals provide reference data for assessing abnormal development in individual cases
- •Growth-related changes in the metacarpal region structures vary by age, suggesting management strategies for flexural deformities may need to be tailored to the specific developmental stage of the foal
Key Findings
- •Superficial digital flexor tendon showed the largest cross-sectional area changes between 10-15 months of age compared to other structures
- •Suspensory ligament was significantly larger than other structures at Day 1, remaining so until 2 months in the region of suspensory origin and 5 months in the region of suspensory body
- •Deep digital flexor tendon demonstrated larger changes than other structures between 2-5 months of age in both measured regions
- •The rate of change in cross-sectional area of each musculotendinous structure varies with age, suggesting differential functional adaptation