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Heat Stroke in Dogs: Causes and Prevention

Warm sunny weather and outdoor activities with our pups bring some of the most joyous times as a pet parent. Hiking, playing at the beach, camping, and road trips are treasured activities for both humans and dogs. Armed with the knowledge of the dangers for dogs that can be encountered while out and about during warmer weather, you can ensure that these activities will be accomplished safely and devoid of canine health emergencies. Heat injuries and heat stroke are more common than pet parents may realize, and fun during warm, humid days needs to be approached with caution and planning.

Thermoregulation in Dogs

To avoid experiencing heat injuries in dogs, it is important to understand a few things. Just like with the regulation of fluids and electrolytes in the body, your dog’s internal temperature must be maintained in a specific range for the optimal function of his internal organs. If a dog’s body temperature becomes too high or low, disruption of cellular processes and the delivery of oxygen and nutrients to cells will cause temporary or permanent organ damage. Your dog’s brain has a thermoregulatory center, which is constantly sensing and gathering information about her body temperature and ramping up heat exchange when necessary (through panting and other means!). The result is that your pup’s normal internal temperature remains at a steady 100.5-102.5℉ at all times, just where her internal organs like it.  

When that thermoregulatory center in the brain senses an increase in body temperature, the dog’s natural heat exchange processes are activated to release excess heat. Believe it or not, that does not include sweating–– dogs have few sweat glands located in their paw pads, but they are not very efficient for heat exchange. Instead, dogs will increase their breathing rate and pant heavily in order to dissipate heat. Each exhaled breath carries humid air out of the lungs to evaporate into the environment, cooling the body from the inside out. 

For most dogs, a large amount of water and heat can be removed through evaporation in a short period of time by panting. Panting is a normal and regulated process, and once the activity that has raised the dog’s temperature has concluded, panting should decrease within a reasonable period of time, especially with rest in a shady spot and drinking cool water. 

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Dangerous Body Temperatures for Dogs

Perhaps your dog’s least favorite part of any veterinary visit is the dreaded temperature check. To your dog’s displeasure, the most accurate way to measure a dog’s internal temperature is – you know it – rectally! You too can take your dog’s rectal temperature at home (unless they are aggressive about you doing so – please do not get bitten)! With the help of another adult assistant for restraint, a cheap digital thermometer, and some water-based lubrication purchased at the drug store and you are all set (make sure to label the thermometer too, so it does not get confused with the family thermometer!)!

As mentioned earlier, the normal body temperature for a dog is in the range of 100.5-102.5℉. A condition called “hyperthermia” occurs if the dog’s body temperature rises above 103℉, and “heat stroke” occurs when the body temperature rises to 105℉ or higher. Unfortunately, if core body temperatures reach 107-109℉, dogs will experience multiorgan or failure and death. Heat exposure can be a serious issue for dogs, but knowing the risks will help pet parents avoid dangerous situations. In an event of heatstroke, a visit to the vet might be in order. 

Dogs Predisposed to Heat Stroke

Brachycephalic Breeds

Some breeds, by nature of their cute, smushed faces, are especially prone to overheating. Any brachycephalic breed of dog (short, squished nose) is very vulnerable to suffering heat injuries. These dogs have a decreased ability to pant and exchange heat efficiently due to their anatomical features. Extra skin tissue in the back of their throat, narrow nasal passages, short respiratory tracts, large tongues, and abnormal windpipes all combine to make them extremely sensitive to ANY increase in temperature. These dogs are very poor at cooling themselves on warm days, and can even die of heat stroke when temperatures are in the 60’s! Breeds like English Bulldogs, Pugs, French Bulldogs, Boston Terriers, Mastiffs, Boxers, Pekingese, etc are all predisposed to heat injuries, and extra care should be taken to avoid exercise outdoors in the heat of the day or in very humid conditions. Special attention should always be paid to their condition while exercising and playing as well.

Other Predispositions to Heat Stroke

  Dogs that have previously suffered a heat injury are more prone to another due to damage to the thermoregulatory centers in the brain

  Dogs with thick hair coats will retain heat and have more trouble cooling down on warm days (Akitas, Huskies, German Shepherds)

  Dogs with dark or black fur coloring absorb and retain more heat (Dobermans, black colored dogs)

  Senior, overweight, or dogs with medical conditions have a more challenging time adapting to warmer temperatures

  Dogs wearing muzzles are unable to pant efficiently

  Dogs that have recently moved to warmer, more humid climates, or rapid changes in weather where dogs are not accustomed to the heat swings

Situational Causes of Heat Stroke

The overwhelming situational cause of heat stroke is dogs locked in parked cars, especially on warm days. Pet parents will even crack the windows while they run into the store, but unfortunately, that is not quite enough. The rapid increase in temperature, even in a couple of minutes, is often underestimated; for example, on a 75℉ day, the internal vehicle temperature can increase 40℉ within an hour even with the windows cracked. This means that a dog could potentially be sitting in 115℉, which is incredibly dangerous and often deadly.  

Another common cause of heatstroke is overexertion or heavy exercise on hot and humid days. Dogs that are not in good physical condition are especially vulnerable to these situations. Lack of breaks, shaded areas to rest, and clean water can also contribute to an inability to thermoregulate efficiently. It even happens with dogs at home on hot days lacking shade and cool water. Less common but still an occurrence to be aware of, exposure to a hot hair dryer for long periods of time, like the drying cage at the grooming salon, is also a known cause of heat stroke in dogs, so care must be taken to avoid extended periods of heat in the drying cages.

How To Prevent Heat Stroke

It is extremely important to NEVER LEAVE DOGS UNATTENDED IN PARKED CARS! Even with the windows cracked. Even if just for a few minutes. This can save your dog’s life and prevent heat injuries.

Being aware of your dog’s exercise abilities and limitations and taking into account the weather and duration of exercise are good places to start when looking to prevent heat stroke. Dogs with health issues, including obesity, should be monitored closely and use caution during exercise on warm days. Offering breaks, cool water access, and shade are also essential during time spent outdoors to prevent dehydration in dogs as well as heat injuries. Limiting exercise to the early morning or later evening, when the temperature is milder and humidity is low, can make exercise safer and more comfortable during periods of warm weather. Dog breeds with smushed faces and difficulty panting should not be exercised in the heat of the day, and careful attention should be given to their condition during time spent outside. After moving to new, warmer environments, or during times of weather swings, gradually introduce exercise until the dog is accustomed to the new climate and seems to tolerate it well.

Enjoying the Great Outdoors With Your Pup

Spending time outside is wonderful for both pup and pet parents, and warmer outdoor temperatures do not condemn anyone to a life of air conditioning indoors. It just means that consideration and careful planning should precede activities when the temperatures and humidity levels rise. Taking into account hydration needs, temperature exposures, fitness levels, and length of the day’s activities will ensure that you and your pup have a wonderful experience together. Monitoring your pup for signs of heat stroke in dogs throughout your outing is also essential to remain safe and healthy. At home, air-conditioned spaces, shaded outdoor areas, and access to fresh cool water will also ensure that your dog is comfortable at all times, no matter the temperature spikes!

Our AskVet Veterinarians are available to discuss all of your pet’s needs 24 hours a day, 7 days a week. Whether you have an immediate need, desire assistance with a heat injury or heat stroke treatment, or are looking to improve your pet’s overall wellbeing, just sign into your account and one of our friendly and knowledgeable veterinary experts will attend to your needs, no appointment required!


Written by:

Alexa Waltz, DVM
Dr. Waltz was raised near the beaches of Southern California but has spent her adult life living all over the beautiful United States while serving in the military and as a military spouse. She left California for the first time to pursue a career as a veterinarian at Louisiana State University School of Veterinary Medicine and graduated as a Doctor of Veterinary Medicine in 2006. She was accepted into the US Army Health Professionals Scholarship Program during vet school and upon graduation spent her military years as a veterinarian in San Diego working for the US Marine Corps and US Navy Military Working Dog programs as well as caring for pets of service members. After her military service, she became a civilian veterinarian and continued as a small animal general practitioner at clinics in California, Rhode Island, Colorado, and Maryland. Dr Waltz loves to see her “in person” patients just as much as communicating with and assisting pet parents virtually on AskVet. Dr Waltz is also a Mom to 3 humans, 2 guinea pigs, and 1 Australian Shepherd and in her spare time she loves traveling, adventures, exercising, and doing just about anything out in nature!


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