Relationship between noseband tightness and noseband pressures in novice horses and riders: Implications for guidance to support horse welfare

Background: The effect of non-ridden exercise on epaxial muscle development has implications for equine training programmes and back injury rehabilitation.However, it is not known whether epaxial muscle hypertrophy differs in horses who are used for load-pulling as opposed to riding only.Objective: To explore whether military horses with a load-pulling specialism have increased epaxial musculature compared to ridden-only military horses.Study design: Cross-sectional. Methods:The back shape of 42 load-pulling and 26 ridden-only military horses was assessed by fitting a flexible curved ruler perpendicular to the horse's back at T10, T13, and T18 and tracing the resulting shape on paper.The ratio of the back trace's width at 3 cm and 9 cm ventral to the dorsal midline (width at 3 cm/width at 9 cm) was used to evaluate back convexity/concavity.Mean width ratios and standard deviations were calculated for both groups and compared using an independent samples T-test (significance level: p 0.05).Results: Mean width ratios were significantly higher for load-pulling horses at T10, T13, and T18 compared to ridden-only horses.The mean (SD) at T10 was 0.4049 (0.0206) for ridden horses and 0.4402 (0.0275) for load-pullers (p 0.001).The mean (SD) at T13 was 0.3965 (0.0248) for ridden horses and 0.4417 (0.0418) for load-pullers (p 0.001).The mean (SD) at T18 was 0.4287 (0.0295) for ridden horses and 0.4868 (0.0433) for load-pullers (p 0.001).Main limitations: Several back traces for T13 and T18 were excluded due to insufficient back trace length, resulting in smaller sample sizes (T10: n = 64, T13: n = 56, T18: n = 46).Conclusions: Load-pulling resulted in increased convexity of the equine back compared to ridden exercise only, likely due to hypertrophy of epaxial musculature.More work is needed to establish the mechanisms underlying the effect that load-pulling has on epaxial muscle development.