Heatstroke in Dogs: Recognizing Symptoms & Cooling Them Down Immediately

What is heatstroke?

Heatstroke in dogs (medically known as hyperthermia) refers to a life-threatening overheating of the body in which the core temperature rises above 41 °C and central nervous system functions are simultaneously impaired. Unlike a fever (an infection-related rise in temperature), heatstroke is a failure of the body’s temperature regulation: the body can no longer adequately dissipate the excess heat.

Dogs primarily cool themselves by panting and—to a lesser extent—through the pads of their paws. These mechanisms fail in extreme temperatures, high humidity, or during intense physical exertion. Without immediate cooling and veterinary treatment, affected dogs will die from organ failure, coagulation disorders, and systemic shock.

Background + Scientific Context

Contrary to widespread belief, heatstroke caused by being left in a hot car is only one of several causes. In a comprehensive UK study, Hall et al. (2020, Scientific Reports) showed that 74.2% of all heatstroke cases were exercise-induced—dogs that were exercised, played with, or walked in hot weather. Only 5.2% of cases were attributable to being left in a vehicle.

Hall et al. (2020, *Animals*) analyzed risk factors and identified brachycephalic breeds (Bulldog, French Bulldog, Pug, Dogue de Bordeaux, Cavalier King Charles Spaniel), obesity, and high body weight as significant risk factors. Due to their narrowed airways, these dogs are significantly less efficient at dissipating body heat through panting.

Depending on the study, the mortality rate ranges from 14% to 50%, despite intensive care treatment. A 2024 study by Yanai et al. (JVIM) showed that coagulation disorders (hypocoagulability) in heatstroke are associated with a poorer prognosis and an increased risk of disseminated intravascular coagulation (DIC). Acute kidney failure and rhabdomyolysis (muscle breakdown) are other typical complications.

Vitomalia-Position

Heatstroke is a preventable emergency—which makes it all the more tragic. We recommend taking consistent preventive measures: schedule walks and exercise for the early morning or evening hours, significantly limit strenuous activity in warm weather, and avoid overexerting brachycephalic dogs even in moderate temperatures. Leaving dogs in vehicles during hot weather is never an acceptable option—even brief stops can be fatal.

In an emergency, the rule is: Protect and cool the dog immediately, and head to an emergency veterinary clinic at the same time. The first 30 minutes are critical to the outcome. Our recommendation for pet owners on the scene: Move the dog out of the sun to a shaded, well-ventilated area or—if possible—into an air-conditioned room. Continuously moisten the entire body with cool (not ice-cold) water, paying special attention to the neck, belly, paw pads, and groin. Create a breeze to aid evaporative cooling. We advise against using ice water or ice packs directly on the skin: pet owners rarely have the controlled conditions of clinical cold-water immersion at home, and uncontrolled ice can lead to skin irritation or cold injury. Stop cooling when the core temperature reaches approximately 39.5 °C to avoid hypothermia.

When does heatstroke become a concern?

Heatstroke in dogs tends to occur more frequently during certain seasons, but it is not exclusively a summer problem. It becomes a concern in the following situations:

• Walking or running in temperatures above 25 °C and high humidity
• Intense physical activity (playing, running, retrieving) in the midday heat
• Staying in poorly ventilated, hot rooms or on hot surfaces (asphalt)
• Visibility in vehicles — even on cloudy days and for short periods
• Brachycephalic breeds are affected even at temperatures that other dogs can still tolerate
• Older dogs, overweight dogs, or dogs with pre-existing cardiopulmonary conditions during moderate exercise

Practical application

Symptoms of heatstroke in dogs:

• Heavy, uncontrolled panting—faster and louder than usual
• Dizziness, loss of coordination, sudden weakness
• Dark red, purple, or pale mucous membranes
• Vomiting, diarrhea (sometimes bloody)
• Confusion, disorientation, seizures
• Collapse, loss of consciousness

Immediate steps to take if heatstroke is suspected (the first 30 minutes are critical):

1. Immediately move the dog out of the sun and into a shaded, well-ventilated, or air-conditioned area.
2. Keep the animal cool by continuously wetting it with cool (not ice-cold) water: the neck, belly, paw pads, and groin—make sure these areas are thoroughly soaked.
3. Use fans or a draft to aid evaporative cooling.
4. No ice water, no ice packs directly on the skin—this poses a risk of frostbite and skin irritation, especially when used improperly at home.
5. At the same time: Call an emergency veterinarian and drive to the clinic immediately—cooling must not delay transport.
6. Do not force your dog to drink — there is a risk of aspiration in dogs that are disoriented.
7. Lower the body temperature to approximately 39.5 °C—then stop cooling (avoid hypothermia).

In the hospital: IV therapy, monitoring of kidney function, coagulation parameters, and lactate levels; intensive care if necessary in the event of complications such as shock, DIC, or acute kidney failure.

Common Mistakes & Myths

• “My dog is young and fit—that won’t happen to him.” Hall et al. (2020) showed that exercise-induced heatstroke particularly affects young, male dogs because they are exercised more intensely. Fitness does not protect against overheating.
• “Ice water cools the fastest.” In a clinical setting under controlled conditions, cold-water immersion is an established method (Bruchim et al. 2017, Hifumi et al. 2019). For on-site handlers, however, we advise against it: ice from the freezer or ice packs placed directly on the skin can cause cold injury, and the response to a collapsing dog under stress is rarely controlled. It is safer and effective enough to continuously pour cool (not ice-cold) water over the body, combined with shade or air conditioning and a breeze—the key factor is the rate at which the core temperature drops in the first 30 minutes, not the final water temperature.
• “I’ll leave the window slightly open—that’s enough.” Studies show that the interior temperature of a parked car can rise by up to 10 °C in 10 minutes—even on a slightly cloudy day with the window slightly open.
• “The dog simply drank too much.” Excessive panting and water intake are early signs of overheating, not a solution to it. If the dog also appears disoriented, emergency care is required.
• “Once he cools down, everything will be fine.” Organ damage (kidneys, liver, brain, blood clotting) can still occur hours after heatstroke. Veterinary monitoring is essential even after clinical recovery.

Current State of Research (2026)

Research on heatstroke has evolved into four main areas: risk factor epidemiology, the pathophysiology of coagulation disorders, preventive measures in the context of climate change, and cooling methods. Hall et al. (2020) established a robust risk profile through the UK study involving 395,000 dogs. Yanai et al. (2024) deepened our understanding of coagulopathy. Bruchim et al. (2017) for dogs and Hifumi et al. (2019) for humans demonstrate that, in a clinical setting under controlled conditions, cold-water immersion is an effective method for rapid cooling. For initial home care by owners, we nevertheless recommend the more cautious approach using cool (not ice-cold) water—controlled cold-water immersion should be performed by a veterinarian. A 2025 Frontiers study analyzed morphological risk factors in the context of rising global temperatures and explicitly recommends including brachycephalic dogs as a high-risk group in heat advisories. Open questions: standardization of preclinical cooling protocols, long-term consequences of survived heatstroke episodes, and the protective effect of cooling vests.

Frequently Asked Questions

At what temperature does the risk of heatstroke begin for dogs?

There is no universal threshold temperature. The relevant factors are the combination of outdoor temperature, humidity, exercise intensity, and breed type. Brachycephalic dogs can show signs of overheating even at moderate summer temperatures and during mild exercise. As a rule of thumb: significantly limit intense exercise on warm days, and on hot days, limit walks to short morning or evening strolls—and always plan activities for brachycephalic dogs with extra caution.

What's the best way to cool my dog down if it has heatstroke?

Immediately move the dog out of the sun to a shaded or air-conditioned area, then continuously moisten it with cool (not ice-cold) water—pay special attention to thoroughly soaking the neck, belly, paw pads, and groin. Create a breeze. Do not apply ice from the freezer directly to the skin, and do not use ice packs—cold damage is possible. Stop cooling at approximately 39.5 °C. The first 30 minutes are critical—take the dog to the vet immediately.

Are certain dog breeds particularly at risk?

Yes. Brachycephalic breeds (Pugs, Bulldogs, French Bulldogs, Cavalier King Charles Spaniels, Dogue de Bordeaux) and overweight dogs are at a significantly higher risk of heatstroke because their ability to cool down through panting is limited.

Can surviving heatstroke have long-term effects?

Yes. Renal insufficiency, neurological deficits, and coagulation disorders may persist even after clinical recovery. Regular follow-up examinations (particularly blood counts and kidney function tests) are recommended by veterinarians following an episode of heatstroke.

Related terms

• Stomach torsion in dogs
• Shock in Dogs
• Poisoning in Dogs
• CPR for Dogs
• Dog First Aid Kit
• Brachycephaly in Dogs
• Symptom: Dog

Sources & Further Reading

1. Hall, E. J., Carter, A. J., & O'Neill, D. G. (2020). Incidence and risk factors for heat-related illness (heatstroke) in UK dogs under primary veterinary care in 2016. Scientific Reports, 10(1), 9128. https://pubmed.ncbi.nlm.nih.gov/32555323/

2. Hall, E. J., Carter, A. J., & O'Neill, D. G. (2020). Dogs Don't Die Just in Hot Cars — Exertional Heat-Related Illness (Heatstroke) Is a Greater Threat to UK Dogs. Animals, 10(8), 1324. https://pubmed.ncbi.nlm.nih.gov/32751913/

3. Yanai, T., Bruchim, Y., et al. (2024). Thromboelastometry for assessment of hemostasis and disease severity in 42 dogs with naturally-occurring heatstroke. Journal of Veterinary Internal Medicine, 38(2), 789–797. https://onlinelibrary.wiley.com/doi/10.1111/jvim.17041

4. Bruchim, Y. (2018). Pathophysiology of heatstroke in dogs — revisited. Veterinary Journal, 233, 94–95. https://pubmed.ncbi.nlm.nih.gov/29435477/

5. Bruchim, Y., et al. (2017). Cooling treatment of heatstroke in dogs — cold water immersion is the method of choice. Journal of Veterinary Emergency and Critical Care.

6. Hifumi, T., Kondo, Y., Shimizu, K., & Miyake, Y. (2019). Heat stroke. Journal of Intensive Care, 7, 1. https://jintensivecare.biomedcentral.com/articles/10.1186/s40560-018-0298-4

7. Frontiers in Animal Science. (2025). Heat stress in domestic dogs: morphological and environmental risk factors for dog welfare in a warming world. https://www.frontiersin.org/journals/animal-science/articles/10.3389/fanim.2025.1679377/full