Heat stress is a prominent issue in the dairy industry that results in approximately $800 million in production losses each year. Signs of heat stress include higher respiration rates and body temperature as well as panting, a combination of drooling and breathing through an open mouth. Identification of early signs of heat stress is important for effective abatement, but the thresholds of when onset occurs are not well defined. Drooling could be a way to identify early signs of increasing heat load. Our objective was to identify the respiration rate and body temperature of cattle at 3 time points: 1) when cows initially began drooling in a day (ID), 2) during other drooling events following the first occurrence in a day (OD) and 3) when they were not drooling (ND). Twenty-four Holstein cows averaging (±SD) 37.5 ± 4.5 kg/d of milk were observed over the course of a summer (12 d/cow; 6 cows at a time; total of 48 d of observation). Respiration rate and signs of drooling, breathing with their mouth open and tongue extended past the teeth were taken every 30 min from 1000 to 1900 h. Body temperature was recorded every 3 min 24 h/d using vaginal loggers. To evaluate body temperature alongside drooling, all readings of vaginal temperature within 10 min of a respiration rate and panting data collection event were averaged and assigned to that time point. During the time period of observation, air temperature averaged 33.3 ± 4.0°C or THI 79 ± 3.2. Least squares means within a mixed model were used to obtain average values. Respiration rates in breaths/min were: ID = 73 ± 2; OD = 76 ± 2; ND = 60 ± 2 (P < 0.001). Body temperature averaged: ID = 38.8 ± 0.05; OD = 39.0 ± 0.05; ND = 38.7 ± 0.05°C (P < 0.001). Taken together, these results indicate that the first occurrence of drool in a day is an early indicator of increased heat load. Drooling occurs at higher respiration rates and body temperature than when no drool is present. Finally, within this data set, any occurrence of drooling could have been utilized by producers as an indicator of increased heat load in cattle.