Dog fur is great protection against the cold but can be a problem in hot weather. This is because, unlike humans, dogs eliminate heat by panting. (Dogs have some sweat glands in the footpads which help with heat dissipation, but only minimally.) When panting isn't enough, their body temperature rises. This can be fatal if not corrected quickly.
What To Watch For
Excessive panting and signs of discomfort indicate overheating. However, it is important to be aware of the ambient temperature and take appropriate preventative measures.
Any hot environment can cause heatstroke, but the most common cause is careless actions such as leaving a dog in a car on a hot day or forgetting to provide shade to an animal kept outdoors.
It is essential to remove the dog from the hot environment immediately. If it is unconscious, make sure no water enters the nose or mouth as you follow these guidelines. Also, do not give the dog aspirin to lower its temperature; this can lead to other problems.
Put your dog in the bath tub.
Run a cool (not cold) shower over your pet, covering the whole body -- especially the back of the head and neck.
Allow the water to fill up the bathtub as you shower the dog. Keep the head elevated to prevent aspiration pneumonia.
If getting the dog into the tub is impractical, use a garden hose to cool the dog or place him in a pool of cool water.
Apply a cold pack to the dog's head to help lower his body temperature -- a packet of frozen vegetables works fine.
Massage the legs. A vigorous rubbing helps the dog's circulation and reduces the risks of shock.
Let the dog drink as much cool or cold water as it wants. Adding a pinch of salt to the water bowl will help the dog replace the minerals it lost through panting.
The following steps should be taken, regardless of whether the dog is conscious, appears to recover well, or was only mildly affected:
Check for signs of shock.
Take the dog's temperature every five minutes, continuing water-cooling until it drops below 103°F (39.4°C) .
If the dog's temperature drops a little more - to around 100°F (37.8°C) - don't worry. A slightly low temperature is a lot less dangerous.
Treat for shock if necessary.
Get immediate veterinary attention. Heatstroke can cause unseen problems, such as swelling of the brain, kidney failure, and abnormal clotting of blood. On the way to the veterinarian, travel with the windows open and the air conditioner on.
Treatment will consist mostly of replacing lost fluids and minerals. This may extend to secondary conditions, which your vet will be able to identify. Intravenous fluid therapy and monitoring for secondary complications such as kidney failure, development of neurologic symptoms, abnormal clotting, changes in blood pressure, and electrolytes abnormalities are typically recommended in cases of heatstroke.
Dogs with thick fur, short noses, or those suffering from medical conditions such as laryngeal paralysis and obesity are predisposed to heatstroke. In addition, dogs that enjoy constant exercise and playtime -- such as working dogs (Labradors, Springer Spaniels, etc.) -- should be closely monitored for signs of overheating, especially on hot days.
Heat stroke can be prevented by taking caution not to expose a dog to hot and humid conditions. This is especially applicable for dogs with airway diseases and breeds with shortened faces (e.g., the Pug, Bulldog, Shi Tzu). Also, while traveling in cars, make sure that the dog is well ventilated by placing it in a wired cage or in an open basket, and never leave your dog in a car with the windows closed, even if the car is parked in the shade. When outdoors, always make sure your dog is in a well-ventilated area with access to plenty of water and shady spots.