Head and Pelvic Movement Asymmetries at Trot in Riding Horses Perceived as Sound by Their Owner.

Reasons for performing study Recent studies evaluating owner sound horses have identified a large proportion of horses with motion asymmetries but the prevalence, type and magnitude of asymmetries have not been investigated. The increasing use of objective lameness evaluation necessitates a further characterisation of the differences between lameness and motion asymmetries. Objectives To investigate prevalence, and quantify type and magnitude of motion asymmetries during straight-line trot in riding horses, perceived sound by their owners. Study design Cross-sectional prospective study. Methods Vertical head and pelvic movement symmetry was measured in 220 Warmblood riding horses, all functioning in daily work and considered sound by their owners; 100 of these individuals had been included in a previous report [1]. Body-mounted uni-axial accelerometers were used and differences between maximum and minimum head ( HDmax, HDmin) and pelvic ( PDmax, PDmin) vertical displacement between left and right forelimb and hindlimb stances were calculated during straight-line trot. Previously used symmetry thresholds (absolute differences >6 mm for the head and >3 mm for the pelvic variables) were used. Results The thresholds for symmetry were exceeded for 159 horses (72%) for at least one variable, HDmax (n = 41, mean 12.7 mm, s.d. 5.5), HDmin (n = 58, mean 14.3 mm, s.d. 7.1), PDmax (n = 87, mean 6.5 mm, s.d. 3.10), PDmin (n = 77, mean 5.7 mm, s.d. 2.1). Contralateral and ipsilateral concurrent fore- and hindlimb asymmetries were detected in 41 and 49 horses, respectively. Conclusions A surprisingly large proportion (72%) of horses perceived as sound by their owner showed movement asymmetries during straight-line trot. It is not known to what extent these asymmetries are related to pain or mechanical abnormalities as opposed to 'normal variation' and this leads to 2 potential welfare problems - either too many horses in training are actually 'lame' or many horses categorised as 'lame' have no locomotor system disease. Ethical animal research: This study was conducted within guidelines of the participating sites institutional animal care and use procedures (C 206/10, C48/13) and informed consent for data collection was obtained from the horse owners prior to the study. Source of funding: None. Competing interests: None declared. [ABSTRACT FROM AUTHOR]