Heat stress is a recurring challenge that dairy farmers throughout Europe must cope with every summer. At temperatures higher than certain thresholds (e.g. an air temperature of 25°C and relative humidity of 10%, or air temperature of 22°C and relative humidity of 50%) cows cannot effectively maintain their body temperature and their entire physiology becomes challenged. Several physiological changes take place as the cow attempts to adapt to these conditions. For example, feed intake reduces, respiration accelerates (which in turn causes an imbalance in the systemic acid-base balance) and excessive saliva is lost via drooling.