I got this in my email from Dr. Andrews and thought I would pass it along.

The signs depend upon the extent of heat stroke. In the early stages, your pet will pant rapidly, have thick, ropey saliva, and have bright red gums. His body temperature will be between 104-106°F.

As the body temperature climbs above 106°F, your pet will go into shock with subsequent organ shutdown.

He will have pale gums, be weak and dizzy, with vomiting and diarrhea. The brain becomes affected and he may seizure or fall into a coma. In this case, he requires immediate, life-saving veterinary intervention.

The normal body temperature of a dog or cat ranges between 38 - 39°C or 103°F. Our pets maintain this temperature through panting, however sometimes they are unable to lose enough heat. Dogs and cats probably do suffer from heat cramps and heat exhaustion like us humans but the symptoms are mild and we don't recognize them. The condition that we see is heatstroke, and it may cause the death of a pet.

SOLUTIONS

AWAY FROM THE HEAT. Remove your pet from the hot environment. Get him out of the car and away from the sun.

TO THE VET ASAP. If you suspect severe heatstroke and your pet has collapsed, get your pet immediate veterinary care. In this case, the organs may be shutting down and he needs specialized care to survive. While in transit it is important to continue to apply cool wet towels to the back of the neck and groin area.

WHAT'S THE TEMP? Use a rectal thermometer and find your pet's exact temperature: if it is 104°F or higher, he has heatstroke, and you need to take action.

COOL DOWN. Run cold water over the back of your pet's head. Place cold packs wrapped in towels between the back legs, on the belly and in the armpits. Wet towels can be used instead. You can use a garden hose to run the water over the back of his head.

ALCOHOL SOLUTION. Rubbing alcohol will also speed up heat loss; it can be applied to the belly and groin, cooling as it evaporates. Liberally spread it on the skin; the most important thing is reducing the temperature in a controlled way.

DO NOT IMMERSE IN COLD WATER. This treatment does bring your pet's temperature down, but tends to overcorrect it and then your pet may be seriously unwell, cold and wet.

RE-HYDRATE. Let your pet drink as much cold water as he can. If you have an electrolyte replacement, such as Gatorade, then add this to his water. If your pet drinks lots of water at once it is very likely to vomit. Once your pet is refusing water you can leave the bowl of water with it.
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It's always wise on a hot and humid day to always have cold water when you and your pet is out in the sun. Your dog should be offered water every 30 minutes. [Sarah]