Heatstroke is defined as a state of extremely elevated body temperature (106-109F). While rare in cats, it occurs frequently in dogs, particularly those that are obese or have upper airway obstruction, e.g. laryngeal paralysis, and in brachycephalics
(Bulldogs, Pugs, Bostons etc), those that are confined in nonventilated areas (cars), deprived of water and/or shade, or subjected to forced heat
(i.e., hot dryers after bathing). Exercising in hot and especially humid weather, even for brief periods of time, can also cause heat stroke.
The pet will appear distressed, restless and will pant excessively.
As the hyperthermia progresses, drooling may be noted, followed by ataxia (unsteadiness). If inadequate oxygenation occurs, you may notice pale or grey gums.
Remove your pet from the environment that caused the heat stroke to occur, into a cooler shaded area.
If possible, drive to the nearest veterinary hospital.
Begin the cooling process, by placing cool wet towels over the head, neck, feet, axillary and groin areas.
Do not submerse your pet in cold water and do not use very cold water or ice for cooling. Cooling too rapidly may be harmful to your pet.
Most importantly, remember to not leave your pet in the car even on a relatively cool day (70F). A recent study from Stanford University found that the temperature in a vehicle may increase by 40 F degrees within one hour, regardless of the outside temperature.