The word stroke comes from “strike,” and, predictably perhaps, heatstroke means “to be struck down by heat.” A pet can suffer heatstroke whenever he or she becomes severely overheated. Signs can include heavy panting, loud breathing, vomiting, disorientation, collapse, coma, and death. Heatstroke can come on quickly and is a dire emergency so it is something pet owners must work to prevent. After cooling a dog down, a veterinarian may need to administer IV fluids and possibly medications. Without prompt treatment a pet is likely to die from heatstroke.


Heatstroke is a life-threatening condition suffered when a pet is unable to lower its body temperature. Cells in the body become damaged when the core body temperature reaches anywhere between 106°F and 109°F. Heatstroke is most common in dogs but can also occur in cats and can happen whenever a pet gets severely overheated.

Among the most common causes of heatstroke in dogs happens when dogs are left in parked cars. One test performed on a partly cloudy, 93°F day found that cars can heat up to 120°F in just 15 minutes. But even cooler days can be deadly. In another test, conducted on a 71°F day, the temperature inside a car parked in the sun with the windows open a crack went up to 116°F in one hour.

Exercising in warm weather or being left outside in high temperatures (especially if the animal doesn’t have access to fresh water or shade) are also common causes.

Factors that may make some animals particularly at risk for heatstroke include obesity and a decreased ability to circulate air through the lungs due to a compromised respiratory tract. Animals with narrow airways, such as those with laryngeal paralysis, or a brachycephalic (short) head, such as Bulldogs and Pugs, are less able to cool themselves efficiently and are particularly at risk.

Heatstroke affects almost every system in the body. Under normal conditions, dogs (and even cats under extreme conditions) will pant to cool themselves as their bodies heat up. Another way they cool themselves down is to send more blood to dilated blood vessels near the skin. Heat radiates off the body, and cooler blood returns to the body’s core.

If an unduly hot environment prevents the normal cooling process, blood is diverted away from important organs such as the brain, kidneys, gastrointestinal tract, and liver. When these organs do not receive enough blood, they begin to fail.

Death is common with heatstroke. It should be underscored here that heatstroke is a medical emergency that must be addressed immediately to give the patient the best chance of survival.

Signs and Identification

Signs of heatstroke include:

  • Panting
  • Loud, rasping breaths
  • Bright red gums
  • Lethargy
  • Vomiting/diarrhea
  • Disorientation
  • Seizures
  • Coma
  • Death
The dog’s body temperature will be checked immediately upon arrival to a veterinary facility. For those whose severe exposure requires hospitalization, blood testing is typically undertaken frequently throughout the treatment process to continually assess and correct the systems that may have been damaged by the heatstroke.

Affected Breeds

All dogs are susceptible to heatstroke. Heat exhaustion and heatstroke occur more commonly in breeds predisposed to laryngeal paralysis, brachycephalic syndrome, and other diseases that might impede normal respiration.


Immediate action must be taken when a pet is found to be suffering from heatstroke since death occurs within minutes of the body’s core temperature reaching 110°F. In a study of 54 dogs with heatstroke, 50 percent of the dogs died. However, 100 percent of the dogs that were given first aid at home and arrived at the veterinary hospital within 90 minutes of being found survived.

Cooling a pet at home by using a cool bath or the garden hose is strongly recommended before transport, as it begins the process of bringing down the body temperature. Never immerse a pet in cold water or ice water!

As soon as a pet with heatstroke arrives at the veterinary hospital, a rectal temperature will be taken and further cooling will begin. If at-home cooling was successful, measures will be taken to reverse the effects of heat, dehydration, and low blood pressure. An IV catheter will be placed, and fluids will be given to help get blood flowing to major organs again.

Treatment is aimed at supporting these organs in the hope that the damage they’ve sustained isn’t permanent. Unfortunately, it will often take days to know which organs have been affected. Specific treatments may include antibiotics, blood pressure medications, and blood transfusions.


In hot weather, it is best to exercise pets during the coolest part of the day (early morning and evening) and always provide plenty of fresh water and rest. It is also helpful to cool your pet with a hose or a swim after exercising and to limit exercise entirely during high temperatures.

Never leave a pet in a car during warm weather – not even for a few minutes with the windows cracked.

Brachycephalic dogs’ owners should be extra vigilant, keeping their dogs inside in air conditioning on hot days.

All geriatric, obese, and respiratorily compromised pets should be exercised with caution in hot weather.

This article has been reviewed by a Veterinarian.