What is Heat Stroke in Dogs and How is It Treated?

Heat stroke is a severe form of hyperthermia, the medical term for elevated body temperature. It happens when a dog's body heats up faster than it can cool itself down. A dog's normal body temperature is around 101 to 102°F. Anything above 103°F is considered elevated, and once it reaches 106 to 107°F, the dog is in serious danger.

The most common cause of heat stroke in dogs is being left in a hot car. A car's windows create a greenhouse effect that traps heat and causes the interior temperature to climb fast, and a trapped dog can't pant enough to keep up.

Dogs left outside without enough shade and water are also at high risk. So are dogs pushed too hard on hot days, like a dog brought along on a long hike when it's too warm out.

The earliest signs of heat stroke are often subtle. Your dog may seem tired or sluggish, or a little confused, which you might notice if you give a command and get no response. Heavy, rapid panting is another early sign.

As heat stroke progresses, a dog may start stumbling, drooling, or vomiting, and the gums often turn bright red. Confusion and disorientation tend to worsen, and eventually the dog may collapse or have seizures.

At the first signs of heat stroke, start cooling your dog right away. If you can, place them in a tub of cool water or run cool water from a hose over their back. If that's not possible or your dog resists, soak a towel in cool water and drape it over their back, refreshing it often so it stays cool.

While you cool them, offer fresh, cool water to drink. Let your dog drink as much as they want, but don't force it. Some dogs with severe heat stroke are too disoriented to drink safely on their own.

If your dog shows more severe signs, call your vet while you give first aid. A dog that's stumbling, disoriented, or unable to stand needs immediate veterinary care.

If you caught it early and your dog seems to be bouncing back, you may not need to rush in, but still call your vet. Even mild heat stroke can cause internal damage or lingering problems, and your vet may want to examine your dog to be safe.

At the clinic, the vet will continue cooling your dog with water and other methods to bring their temperature down. They'll usually give intravenous fluids to replace lost water and minerals, and may run blood tests and other diagnostics to check for organ damage or other internal problems.

Heat stroke is always a veterinary emergency. Even fairly mild cases can damage the kidneys, brain, and other organs, and cases that aren't treated quickly often lead to permanent damage or death. If you suspect heat stroke, don't take a wait-and-see approach. Start first aid and call your vet.

The best way to avoid heat stroke is to watch the temperature and take extra precautions when it's hot. Leave your dog at home rather than bringing them along on errands where they'd wait in the car. Limit long walks and strenuous exercise to early morning and late evening, or try cooling activities like swimming. Make sure your dog always has a shady, well-ventilated spot to rest, and plenty of cool, fresh water. A good rule of thumb: if it's too hot for you outside, it's too hot for your dog.

Some dogs are more prone to heat stroke than others. Dogs with thick, heavy double coats, like huskies, overheat faster than dogs with lighter coats. Older dogs and overweight dogs also struggle more in the heat. Brachycephalic breeds, the ones with short, flat muzzles like pugs, bulldogs, and boxers, are especially vulnerable because they can't pant as effectively. And a dog that's had heat stroke before is more likely to get it again.

Most people only worry about heat stroke when the temperature soars, but it's a danger even on mild days, especially in cars. A parked car heats up fast: the interior can climb about 20°F in just 10 minutes and keep rising, topping 110°F within an hour on a 70°F day. The greenhouse effect heats the car about the same amount whether it's 70°F or 100°F outside, and cracking the windows barely helps. Even a 60°F day can push a car past 100°F. For outdoor activity, the risk depends on your dog's health, the humidity, and other factors, so watch for signs of heat stroke on any warm day, especially during hard exercise.