A central issue of animal welfare studies has been, and continues to be, how can we measure animals’ welfare? Among measures, health-related and physiological disorders appear as the most universally accepted indicators of altered welfare. However, some disorders could be difficult to assess directly, and consequently could be unappreciated. Moreover, even if good welfare starts with physical condition, it does not stop there and visible indicators reflecting the animals’ internal state (mental well-being) must also be considered. Here we propose to present a critical review of welfare indicators in horses, then to present results from a first multidimensional study about horses’ welfare performed in 59 horses coming from riding schools. The aim of this study was to identify reliable and visible indicators of the horses’ welfare state, based on a multidimensional approach including health-related, physiological, behavioural and postural measures. Here we identified several visible postural and behavioural indicators that were clearly associated with altered welfare (i.e. presence of health-related disorders). Moreover, these indicators differed between riding schools, allowing us to identify riding schools’ welfare profiles in addition to individual profiles. As a previous study revealed a relationship between horses’ altered welfare and their aggressiveness towards humans, these visible postural and behaviours indicators are crucial to help professionals and non-professionals to identify their horses’ welfare state and consequently to prevent accidents