A multimodal approach to equine thoracolumbar myofascial pain: integrating clinical examination, AI-based gait analysis, and the ridden horse pain ethogram

BACKGROUND: Myofascial pain syndrome (MPS) is considered highly prevalent in horses, yet it is frequently underdiagnosed due to limited understanding of its clinical presentation and functional consequences, as well as the inherent challenges associated with its clinical assessment and objective measurement. In equines, the relationship between palpation-based MPS indicators, gait asymmetries, and pain-related behaviours during ridden work remains unclear. The primary aim of this study was to evaluate the association between thoracolumbar palpation pain scores and gait asymmetries measured in-hand and during ridden exercise, as well as behavioural indicators of pain assessed using the ridden horse pain ethogram (RHpE). The secondary aim was to explore the effect of a rider on gait asymmetry using a within-horse comparison between in-hand and ridden conditions. Clinical and behavioural signs and demographic variables were also described. RESULTS: Twenty police working horses from the Special Mounted Unit of the Spanish National Police in Madrid were included. At least one myofascial trigger point, identified by a palpable taut band and a hypersensitive spot, was identified in all horses (100%) in the thoracolumbar region, followed by the jump sign (85%) and restricted range of motion (80%). Local twitch responses were not observed in any horse (0%). Clinical indicators of MPS were not associated with objective gait asymmetries measures in either condition. Forelimb push-off asymmetry (HDmax) increased under ridden conditions (β = 0.196, 95% CI 0.028-0.034, p = 0.022). Training level modified this effect, with higher-level horses exhibiting greater increases in HDmax when ridden. The mean RHpE score was 7.2, with 40% of horses scoring ≥ 8 behaviours. The most frequent behaviours were ears rotated back (95%), mouth opening (95%), and intense stare (80%). No significant associations were found between RHpE scores and either MPS clinical signs or ridden gait asymmetries. CONCLUSIONS: This is the first study integrating palpation-based assessment of thoracolumbar MPS with objective gait analysis and the RHpE. The findings suggest the importance of palpation as the primary diagnostic approach for MPS in horses and indicate that a multimodal approach may improve the understanding and management of equine MPS.