At what heat index do horses primarily rely on sweating to cool down?

Horses primarily rely on sweating to cool down at a heat index of 140. When the heat index reaches this level, the environmental conditions can be quite extreme, with high humidity and temperature making it difficult for horses to dissipate heat through normal means. Sweating becomes a crucial physiological response to help regulate the horse's body temperature under such stress.

At a heat index of 140, the body's temperature can rise significantly, and sweating is the primary means of cooling, as it allows for moisture evaporation which draws heat away from the body. This process is vital for maintaining a safe core temperature and the overall well-being of the horse. Understanding this threshold is important for horse owners and riders to prevent heat stress and ensure proper care during hot weather conditions.