Back pain and vertebral disorders are more and more pointed out as a primary source of welfare impairment in working horses. If a global consensus exists on the impact of riding techniques and postures at work on the development and prevalence of back pain, the identification of reliable indicators of such disorders is more difficult. Scientific publications on the subject show that in most cases, the prevalence of vertebral disorders is strongly under-estimated by both professionals and owners, highlighting the urgent identification of visible indicators. The expression of back disorders can be at different levels, according to the type of disorder and to the individual affected, and are rarely specific of back pain. Behavioural changes, in the form of chronic modification of the behavioural repertoire (emergence of abnormal behaviours: teeth grinding, groaning...) and time budget (increased restlessness, reduced locomotion), or the modification of interactive behaviours (increased aggressiveness towards both humans and congeners) might reveal the presence of back problems. Immediate behavioural and postural reactions (tail swishing, backing up, head-tossing, nose tilting...) can be observed in response to work constraints/inadapted riders’ actions when ridden. Unwished behaviour when ridden can also result from a chronic state of back pain. Physical changes, such as lameness, abnormal weight distribution, more or less subtle changes in gaits, feet anatomy and orthopedic status can also reveal the presence of back pain. Last but not least, chronic neck and back postural changes may inform on the emergence of back/vertebral disorders. Because these postural alterations are elicited repeatedly, they may lead to chronic postural profiles. Our recent studies using geometric morphometry reveal the potential relationship between the welfare state, working conditions and chronic postural profiles.