Prevalence of vertical movement asymmetries at trot in Standardbred and Swedish Warmblood foals.
Authors: Zetterberg Ebba, Leclercq Anna, Persson-Sjodin Emma, Lundblad Johan, Haubro Andersen Pia, Hernlund Elin, Rhodin Marie
Journal: PloS one
Summary
# Editorial Summary: Movement Asymmetries in Young Foals Researchers used inertial measurement unit technology to assess vertical movement symmetry in 54 clinically sound foals (31 Swedish Warmbloods and 23 Standardbreds) aged 4–13 weeks during trotting, measuring head and pelvis displacement between left and right stance phases. The prevalence of measurable asymmetries was striking: 83% of Standardbred foals and 45% of Swedish Warmblood foals exceeded predefined asymmetry thresholds (>6 mm for head movement, >3 mm for pelvic movement), despite showing no clinical signs of lameness or pain. These findings suggest that vertical movement asymmetries in young horses may reflect inherent biological variation rather than pathology alone, since foals have minimal exposure to the repetitive loading and trauma typically associated with lameness development. Critically, Standardbred foals demonstrated comparable asymmetry prevalence to previously reported yearling trotters, indicating breed-related differences in movement patterns that warrant further investigation. For practitioners interpreting objective symmetry data, these results underline the importance of establishing breed-specific and age-appropriate reference values, as movement asymmetry does not automatically indicate clinical significance in immature horses.
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Practical Takeaways
- •Movement asymmetries are common in clinically sound young foals and should not automatically be interpreted as pathological or indicative of pain—baseline asymmetry appears normal for the species
- •Standardbred foals show naturally higher movement asymmetries than Swedish Warmblood foals; breed-specific reference ranges are needed when using objective motion analysis systems in young stock
- •Objective symmetry measurements in foals require careful interpretation; asymmetry thresholds derived from adult or lame populations may not be appropriate for assessing soundness in young animals
Key Findings
- •83% of Standardbred foals and 45% of Swedish Warmblood foals aged 4-13 weeks showed vertical movement asymmetries exceeding defined thresholds, despite being considered sound by owners
- •Standardbred foals demonstrated significantly higher prevalence of asymmetries compared to Swedish Warmbloods, suggesting breed-specific predisposition
- •Movement asymmetries in young foals were comparable to previously reported asymmetry prevalence in yearling Standardbred trotters, indicating asymmetries may persist from early age
- •High prevalence of asymmetries in sound foals suggests biological variation rather than pain-related lameness as a potential cause