We have discussed this on our blog before, but it is such an important topic that it is worth repeating. Every summer we see dogs with heatstroke. Heatstroke results from significantly elevated body temperature, causing multiple organ failure and potentially death, even with aggressive treatment. A dog with heatstroke will typically pant rapidly, drool, vomit and become weak or mentally unresponsive.
Dogs do not sweat the way we do. They cool themselves by evaporating water in their airways through panting. Dogs with shorter noses (e.g., pugs, bulldogs, chows) cannot cool themselves as effectively as other breeds and are more susceptible to heatstroke. High humidity also makes it more difficult for dogs to cool themselves.
In hot weather it is best to keep your dogs inside and only exercise them in the cooler hours of early morning or late evening. Make sure they have easy access to plenty of fresh water. Under no circumstance should you leave your dog in the car, even for a few minutes! The temperature inside a car can soar to 120 degrees in a matter of minutes, even with the windows cracked.
If you think your pet may be suffering from heat stroke, get them to a vet immediately. In the interim you can try to cool them off by dousing them with cool (but not COLD water) especially on the groin, arm pits, and paws. You do not want to soak them completely with cold water. This can cause shock and can also cause the blood vessels to constrict, thereby trapping heat inside the body.