Heatstroke in Dogs (and Cats)


1. What is heatstroke, and what happens to a dog’s body when they are having one?

  • Heatstroke occurs when the body can not get rid of excessive heat. It is EXTREME hyperthermia at the body’s core (usually a body temperature of 105-109 degrees F) and this extreme heat causes damage to many different tissues of the body.  For perspective, a dog’s NORMAL body temperature is 100-102.5 degrees F.

2. In what types of situations are dogs most at risk for having heatstroke?

  • Most people think of heatstroke classically in dogs left outside on a hot, humid day with no access to water.  While excessive environmental heat and humidity can definitely be risk factors to the development of heatstroke, there are many other situations that place a dog at risk:
    • Dogs kept in enclosed or unventilated areas, such as cars, grooming dryer cages, etc, including lack of access to water and lack of shade
    • Excessive exercise
    • Anesthetic complications (known as malignant hyperthermia)
    • Dogs with paralysis of their vocal cords (known as laryngeal paralysis)
    • Dogs with excessive seizure activity

3. Are dogs more prone to developing heatstroke due to breed or age?

  • As mentioned above, dog breeds that have “brachycephalic syndrome” (the short- nosed, flat-face breeds with upper airway disease, narrow nostrils, small windpipe or trachea and other abnormal respiratory anatomy) are very high risk for heatstroke.  These include English bulldogs, Boston terriers, Pugs, Pekingese and related cross breeds.  Other risk factors include:
    • The very old and very young dogs of any breed
    • Previous history of heat-related disease
    • Obesity
    • Cardiovascular disease
    • Asthmatic patients
    • Dogs with very thick hair coats
    • Dehydrated patients
    • Poorly controlled epileptic patients with frequent seizures

4. What are the signs of heatstroke that a dog owner could notice?

  • Each case of heatstroke varies a bit depending on the duration of time the dog’s body has been at a higher body temperature and the number of risk factors present. Some of the signs an owner may notice if a dog has heatstroke could include:
    • Excessive panting
    • Excessive drooling
    • Reddened gums and other moist tissues of the body
    • Lack of urine production
    • Skin that is hot to the touch, or if measured by thermometer, a body temperature of over 103 degrees F.
    • Vomiting blood and/or diarrhea (black, tarry stools)
    • Weakness, wobbly incoordinated or “drunken” gait
    • Head Tremors
    • Seizures and/or muscle tremors
    • Changes in mental status
    • Collapse

5. If you suspect your dog is experiencing heatstroke, what steps should you take to help them?

  • Heatstroke is always considered an emergency and the first decision to make immediately is where and how to bring your dog to receive veterinary care as soon as possible. Once at a veterinary hospital, your dog will be assessed and triaged and appropriate, controlled cooling methods will be started immediately.   Intense cooling, such as plunging a dog into an ice bath, is STRONGLY contraindicated because it will cause the blood vessels at the extremities to constrict.  This causes the core body temperature to rise even more.    However, on the way to the veterinary hospital, some home strategies can be done to help, including wrapping the dog in a lukewarm, wet towel, wetting the pads of the feet with rubbing alcohol and placing a fan in front of the patient.

6. If is confirmed that your dog suffers from heat stroke, can there be any lasting side effects from it?

  • As is the case with many diseases, the earlier the patient receives medical therapy, the better the prognosis. However, in some cases, complications can occur, including sudden kidney failure, liver failure, gastrointestinal dysfunction, clotting difficulty, and in 36-50% of patients, this disease can be fatal.   This shocking but accurate statistic highlights the importance of EARLY and AGGRESSIVE therapy for dogs with heatstroke.

7. What can you do to help prevent heatstroke in dogs?

  • I encourage dog owners to first identify if their dog has any of the risk factors listed above, such as breed, age, chronic disease, previous history with heat-related illness, etc. If that is the case, I encourage avoidance of situations that would place the patient at risk.  Exercise these dogs before 10 am and after 4 pm during the warm months.  Avoid leaving these dogs in cages at the groomer with dryers for extended periods of time or in unventilated areas such as cars.  Always provide fresh, ample water when outside and plenty of shade.  And, most importantly, AVOID using ice baths or other extreme methods of cooling if there is concern of hyperthermia, or increased body temperature.  Seek prompt veterinary medical attention as described above.

8. How common is heatstroke in dogs in Chicago?

  • Chicago summers are usually quite warm and humid, the perfect environment for dogs to develop heatstroke. Unfortunately, this syndrome is too common this time of year.

9. Heatstroke is probably more common in the summer, but are there many instances of it at other times of the year?

  • Answered above (overheated at grooming salon, dogs with risk factors in unventilated areas, etc).

10. Can heatstroke occur in cats, and does it present itself differently than heatstroke in dogs?

  • Yes, heatstroke can occur in cats, just as in dogs. It typically happens in cats exposed to a hot, humid outdoor environment without shade or water, or in breeds with flat faces, such as Persians.   Cats look very similar to dogs with heatstroke, but may show more sudden difficulty breathing.  Cats should NEVER open their mouth to breathe, and if they do, it is considered an emergency.