Intense summer heat and high humidity often drives people to the beach, the lakes and the shade. If you think it’s hard for people to cool off, it’s even harder for dogs. Hyperthermia, the raising of a dog’s core body temperature above normal, is a serious condition. Fortunately there are steps to help prepare your dog for exercising outside when the temperature and humidity start to rise. Prepare yourself by knowing the signs and steps to take if your dog overheats.


National Heat Awareness Day, the last Friday in May, draws attention to hyperthermia or Heat-Related Illness (HRI). While HRI affects people, it also impacts our dogs. Canines can experience two types of HRI: non-exertional and exertional.

According to Russ Kelley, the Scientific Services Nutritionist at Eukanuba’s™ Pet Health and Nutrition Center, “HRI comes when a dog’s core body temperate increases faster than he can cool off. Non-exertional HRI typically is associated with dogs left in cars with the windows rolled up. Exertional HRI is when a dog’s activity causes their body to generate more heat than he can dissipate. If you like to get outside with your dog then be aware that they can overheat when running, hiking, or training. The hotter the weather the harder it is for a dog to cool off.”

While a human’s normal body temperature is 98.6°F, a dog’s normal temperature falls within a range of 99.5-102.5°F. The higher the dog’s temperature the greater his risk, especially when his temperature climbs over 104°F.


While HRI can occur in any season it’s more prevalent in the summer. About 70% of a dog’s internal heat is released through his skin. 1 Hot temperatures offset that release making it harder for active dogs to cool off. Summer breezes aren’t always cool enough to have a positive effect, either.

Panting is the exchange of internal air for external air, but when the temperatures don’t differ that much then dogs struggle to cool down. Dogs do perspire through their paw pads, but the amount of heat released is minimal, particularly if their pads are calloused.

Before heading outside to exercise your dog use the following guideline: add the outside temperature to the humidity percentage. If that number is over 140, then avoid rigorous outdoor activities. Instead run your dog in the morning or evening which are the cooler times of the day. When you do head out, be sure to hydrate your dog regularly and take frequent breaks in a cool, shady area.


Dogs that are at the greatest risk of exertional HRI are ones that are overweight, sedentary, and used to living in the air conditioned indoors. In addition, dogs with shorter, flatter faces or thicker hair coats will be challenged when exercising in hot, humid conditions. The upside is there are ways to prepare your dog to run in hot temperatures.

For starters, assess your dog’s current state of health. Review his body condition score to determine if he needs to shed some weight. If he does, help him lose weight by identifying his daily caloric needs with your veterinarian and feed him the appropriate amount. The next step is conditioning. Sedentary dogs need to start slow and that means light exercise like walking. As they develop muscle tone and stamina, progressively increase their exercise to include short runs. Give them frequent breaks and build slowly and steadily.

Dogs that live in air conditioning need to be gradually exposed to the outside temperatures. If possible keep their room warmer than the rest of the house and get them outside for short intervals on a regular basis. It’s always a great idea to consult with your vet about your dog’s overall health and weight before starting any significant increase in activities.


According to Kelley, “If you’re running dogs outside in the heat then be aware of the three stages of HRI and be prepared to take action should a problem arise.”

Heat Stress The first sign of an overheating dog is when they are less animated than normal. They run at a slower pace and look visibly tired. They’ll pant heavily, often pulling back their lips to reveal their full arcade of teeth. They may have an attitude change and appear apprehensive.

Action Plan Take a break from the activity. Sit in a shady area with a cool breeze. If there isn’t a shady area, turn on your vehicle and its air conditioner. When the car is cool, let the dog rest inside. Rinse out the dog’s mouth, gums and tongue with water distributed from a squirt bottle. Rub alcohol-soaked pads to the pinnae of the ears, in the groin, and in the armpits.

Heat Exhaustion Dry mouth, pasty saliva around their gums and nose, a visible slowing when running, and sunken eyes indicate that your dog is suffering from heat exhaustion. Their panting becomes uncontrollable, and they may vomit or have diarrhea. Some stumbling may occur as well as an overall weakness in the body.

Action Plan Get your dog immediately to a vet. Before you travel, place a cool, wet towel on the bottom of his kennel. Be sure the crate is large enough so he can lay on his side as stretching out allows for maximum heat dissipation. Apply cool water to his paws and rub an alcohol-soaked pad to the pinnae of the ears, armpits and groin area. Turn on a cage door fan. Never put dogs in extremely cool water and don’t put ice directly on the dog’s skin. The extreme cold causes the surface blood vessels to shrink and increases dehydration and heatstroke.

Heat Stroke Owners that see dogs lose coordination, become unsteady, and are overall unresponsive are in trouble. Sometimes dogs don’t urinate, and if they do the coloration is dark. Seizures leading to shock may occur. Stupors, seizures, and head tremors accompany this phase.

Action Plan Get your dog immediately to a vet. Before you travel, follow the same steps noted in the action plan for heat exhaustion above.


Dehydration is common with HRI, so be sure that dogs have plenty of cool, fresh water to drink. Proper hydration helps dogs thermoregulate. For example, a 44-pound dog can lose between .5 and 1.5 gallons of water per day so he’ll need to drink at least that amount (preferably more). After dogs drink, their bowl may be filled with white, pasty saliva rinsed from their mouths, so be sure to regularly freshen their water.

Sometimes, dogs don’t drink as much water as they should, and you can increase their intake by adding water to their dry kibble. Water baiting works too, and that is adding a tablespoon of wet dog food to a bowl of water. As the dog tries to get the food he’ll consume more water.

A common method for determining daily water consumption can be calculated by food volume. Simply multiply the number of cups of dry food offered daily by 3 cups. So, two cups of food means the dog should drink 6 cups of water, and so on. Keep in mind that this target is the minimum amount of water your dog should be drinking daily when working under adverse conditions

To make the most of outside activities with your dog this summer, take steps to safeguard him against HRI. Spend time properly acclimating him to the warmer weather and slowly condition him to an enhanced fitness level. By educating yourself on the signs and actions to take should your dog begin to overheat, you will be better prepared to quickly get him the help he needs.

To learn more about heat related illness (HRI) in dogs, visit

1 Bruchim Y, Horowitz M, Aroch I. Pathophysiology of heatstroke in dogs: revisited. Temperature. 2017;4:356–370. doi: 10.1080/23328940.2017.1367457. (