Horses are susceptible to heat-related illness during exercise in hot and humid conditions, with appropriate prevention and rapid treatment essential to preventing serious welfare harms.
Heat stress in horses causes acute suffering through physiological distress, weakness, and potential collapse. In severe cases, heat stroke can cause organ failure and death. Working horses in inappropriate conditions - high heat and humidity combined with intense exercise - is a serious welfare failure. Even moderate heat stress affects welfare, causing discomfort, reduced willingness to work, and physiological strain. As climate change increases the frequency of extreme heat events, proactive heat management becomes increasingly important for working and competition horses. The responsibility lies with owners, riders, and event organizers to make evidence-based decisions about when conditions are too hot for safe exercise.