The three stages of HRI are heat stress, heat exhaustion and heat stroke.
Clinical Signs of heat stress include less animated behavior, visibly tired or moving at a slower pace, changes in the dog’s focus or readiness, change in attitude, excessive panting, pasty saliva in the mouth, increased thirst, feels overly warm to the touch, tongue excessively protruding out with a flattened end, cheeks pulled back revealing the full arcade of the teeth including the molars, brick red mucous membranes, heat cramps or muscle spasms.
Clinical Signs of heat exhaustion include any of the signs from Stage 1 plus additional signs: weakness or stumbling, mentally aware but too tired to react, excessive panting becomes uncontrollable, significant thirst, sunken, dry eyes, dry mouth, gums and nose, vomit or diarrhea, lack of skin elasticity, muscle tremors.
Excessive panting is a sign that a dog is too hot.
The dog’s normal core body temperature ranges between 99.5°F-102.5°F.
When a dog exercises, his body generates excessive physiological heat which causes his body temperature to rise.
Most of a dog’s internal heat is dissipated through the skin.
Some heat is released by perspiration through his paw pads and nose.
Additional heat dissipates through panting.