Rabbits are unable to sweat and the major pathways by which they can get rid of excess heat are via their ears and by open mouth breathing. They have also evolved to be experts at concealing signs of discomfort or distress, considering that they are among the most common prey animals.
When you notice that your pet rabbit is suffering from heat stroke, gently pick him up and place him in a room where there’s a fan or air conditioning.
Take steps to bring down the rabbit’s body temperature by spritzing his coat with cool but NOT icy or freezing water so there is a gradual reduction in the body temperature of the rabbit. Avoid cooling the rabbit too quickly by using ice water because it can cause shock. Offer some water to drink. Getting the rabbit hydrated should be done ASAP. Seek veterinary attention for your pet if he is not showing any signs of improvement.