Heatstroke occurs when a person or an animal is exposed to excessive heat and the body’s core temperature rises out of a safe range. A human body cools itself by sweating, but dogs and cats sweat only through the pads of their feet—not through glands all over their bodies. Combine that with the fact that most animals’ bodies have a lot more hair than human bodies do, and you’ll see why pets (especially dogs) are so susceptible to heatstroke.

Heatstroke in humans and in animals is very serious—sometimes even deadly.

How do dogs and cats cool off if they can’t sweat?

The only way dogs and cats can cool themselves is by panting; when a dog or a cat pants, he breathes in air that is cooler than the air in his body (which comes out as his breath). But if the air he breathes in is extremely hot, the exchange of air does him no good. This is why the potential for heatstroke increases when it’s very humid. When a pet breathes in humid air, he’s essentially just exchanging the warm, wet air in his body for more warm, wet air outside of his body. It’s also why you should never leave your pet in a parked vehicle without the air conditioner running, even if it’s “just for a minute.” The temperature inside a car in the summer can reach 125° to 140° F within minutes, even with the windows rolled down.

In the Texas Panhandle, a lot of heatstroke cases occur when animals are taken to Palo Duro Canyon. The temperature in the canyon is usually around 10° to 15° F hotter than it is up on the ridge. If you take your animal hiking in the canyon, take lots of water for him (about a gallon for every two hours he’ll be out there) and make frequent stops so that he can drink. (This is a good idea for you too.) In addition, if your dog has been a bit of a couch potato during the winter, get him used to physical exertion again before taking him on a physically demanding hike. Take him on short walks in the park or through a neighborhood and gradually increase the distance; also, make sure to train him in the type of weather you’ll be hiking in. If you’re going hiking at 10:00 a.m., when it will be 100° F in the canyon, train your dog beforehand in the middle of the afternoon, when it’s 100° in your neighborhood.

How do I recognize heatstroke?

A dog or cat suffering from heatstroke may display one or more of the following signs:

  • Rapid panting
  • Bright red or purplish tongue (normal is pink for most breeds)
  • Red or pale gums (normal is pink for most breeds)
  • Thick, sticky saliva
  • Distressed expression on the face
  • Depression or lethargy
  • Weakness
  • Dizziness
  • Vomiting, sometimes with blood
  • Diarrhea
  • Collapse
  • Coma

What should I do if my pet is suffering from heatstroke?

  • Remove your pet from the hot area immediately.
  • Wet him down completely (including the pads of his feet) with tepid water and turn a fan directly on his face. Do not use very cold water: lowering his temperature too quickly can cause a number of other life-threatening problems. You can set a bowl of ice in front of the fan, though, which will cool the air from the fan even more.
  • Take him to your veterinarian immediately. If your pet’s temperature reached a critical level, his condition could be life-threatening. Even if he appears to have recovered from the heatstroke, he may have become severely dehydrated or have developed other complications.
  • When transporting your pet to the vet clinic, wrap ice cubes or ice packs in a moistened towel and place the towel around your pet’s neck and head (but don’t cover his face; he needs to be able to pant). This cools the blood circulating to and from the animal’s brain. Don’t forget to aim an air conditioning vent in your car directly at your pet’s face so he can breathe in that cool air.
  • Allow free access to cool water, but don’t try to force him to drink. A pet suffering from heatstroke typically won’t want to drink; he’ll be too focused on panting. If he does decide that he’s thirsty, that’s actually a good sign. But don’t let him drink too much water at once: let him have a few swallows, then take the water away and let him have some more a few minutes later.

What will my veterinarian do?

Your veterinarian will continue to attempt to lower your animal’s temperature and will likely administer IV fluids with antibiotics. Severe cases sometimes also require oxygen. The vet will probably also check for shock, respiratory distress, intestinal tract bleeding, kidney failure, abnormalities in the heart, brain swelling, and other complications. She might also take blood samples and monitor your pet’s blood clotting time.

The amount of hospitalization required will depend on how high your pet’s temperature got and how extensive the internal damage is. Temperatures of 107° F or higher will destroy sensitive tissues in the intestinal tract, lungs, and brain. Typically, it’s possible to tell within 24 hours of hospitalization whether the animal has suffered any permanent damage as a result of the heatstroke.

How can I prevent heatstroke?

Any pet that cannot adequately cool himself off is at risk for heatstroke, and an animal that gets heatstroke once becomes much more susceptible to it from then on.

Keep older pets and pets with any kind of medical condition (heart disease, obesity, breathing problems, etc.) inside or in the shade. Even normal activity in the heat presents a high risk of heatstroke in these animals.
Be especially careful if your dog is a brachycephalic breed (with a short nose and a “smushed face” appearance). Examples of brachycephalic breeds include English bulldogs, American bulldogs, pugs, Boston terriers, and Pekinese. These breeds are particularly susceptible to heatstroke because of how their skulls—and thus their airways—are shaped.
Provide access to water (preferably cool) at all times. There have been a number of articles circulating on the Internet that claim that giving your pet ice water will kill him. This isn’t entirely accurate: ice water can cause bloating if a pet drinks too much of it, and bloating can be a very serious medical issue that is potentially deadly. However, this is true of any temperature water. A pet shouldn’t be allowed to gulp and gulp and gulp water regardless of how cold it is.
Don’t leave your pet in a parked car, even if it’s in the shade and the windows are rolled down.
Make sure outside pets have access to shade. If you have a good-sized backyard, try buying a kiddie pool and keeping it filled with water. Some pets love to jump in and out simply to wet themselves down, and others will actually lie down in the pool and just hang out in the water.
Don’t take your dog jogging or hiking unless he’s been conditioned for it beforehand (see above).
Don’t muzzle your dog when it’s hot. This keeps him from panting.
Avoid places where heat is reflected off of the ground (the beach, parking lots, concrete playgrounds, etc.) and there is no shade.