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Heat Stroke In Dogs

man and dog walking in field

Heat stroke occurs when a dog’s body temperature rises above 106°F (41°C).  It begins with heat exhaustion when the body temperature rises to between 103°F and 105°F.  A dog’s normal body temperature is 101°F to 102.5°F.  It should be noted that heat exhaustion/stroke is different from fever which is a normal internal physiologic process secondary to infection or inflammation.  Heat stroke is the result of an external stressor on the body and is not a normal physiologic process but the evolutionary lack of a physiological process, namely the ability to perspire.

Dogs do not have sweat glands in their skin and therefore must cool by panting.  On a day when there is less than a 10-15-degree temperature differential between their breath and the air for heat exchange, this is not a very effective cooling method.  The few sweat glands they have in their feet are minimally effective at heat dissipation.  When panting is not enough to keep cool, their body temperature rises leading to heat stroke, shock and cardiac arrest.

Signs of heat exhaustion and heat stroke include the following:

  • Panting
  • Dehydration
  • Excessive drooling
  • Bright red tongue
  • Blue, red or pale gums (normally pink)
  • Production of only small amounts of urine or no urine
  • Rapid heart and/or irregular heart beats
  • Increased body temperature – above 103° F (39° C)
  • Vomiting (with or without blood present)
  • Passage of red blood in the bowel movement or black, tarry stools
  • Changes in mental status
  • Muscle tremors
  • Lack of coordination, wobbly
  • Small, pinpoint areas of bleeding on the gums, eyes or non-haired skin

One of the very early, subtle signs can be lack of responsiveness to commands. Dogs tend to want to please their owners and respond quickly to commands. If you call your dog’s name and he does not look at you or come to you but rather walks away, this can be a very early, recognizable sign of heat exhaustion.  This should be an immediate cue to get him out of the heat.

It is important to note that some dogs may be more sensitive to the effect of heat than others.  As with people, the very old and the very young are susceptible.  Those dogs with thick fur, short noses with pushed in faces, and medical conditions such as laryngeal paralysis, respiratory and cardiac disease and obesity are also predisposed.  Healthy dogs that enjoy (or need) constant exercise or playtime should be monitored closely.  Remember that the most common cause of heat stroke in dogs is human carelessness.  Leaving a dog in a car on a hot day, even with the windows open, for just a few minutes can be dangerous or fatal.  Putting a dog outside on a hot day without adequate shade or water is also dangerous.  Remember the amount of shade present at any point in the day will change with time.

If your dog is just beginning to show early signs of heat exhaustion and his temperature is less than 104°F, the following things can be done at home if immediate veterinary care is not available. 

  • Put your dog in the bath tub.  Run a cool (not cold) shower over your pet, covering the whole body — especially the back of the head and neck.
  • Allow the water to fill up the bathtub as you shower the dog. Keep the head elevated to prevent aspiration pneumonia.
  • If getting the dog into the tub is impractical, use a garden hose to cool or cover him with cool, wet towels.  A fan can also help dissipate heat faster. 
  • Apply a cold pack or a package of frozen vegetables to the dog’s head to help lower his body temperature.
  • Massage the legs. A vigorous rubbing helps the dog’s circulation and reduces the risks of shock.
  • Let the dog drink as much cool water as he wants.
  • Check his rectal temperature every 5 minutes and stop once the dog’s temperature has reached 102.5°F to 103°F.
  • Seek veterinary care as soon as you are able.

If your dog’s temperature is greater than 104°F or he has collapsed, seek veterinary care immediately. Call ahead and let them know you are coming so they can be prepared.  Do the following on the way to the veterinary hospital:

  • Immediately remove your dog from the hot area to a cooler location.
  • While transporting him, place cool, wet towels over the back of the neck and chest, under the forelimbs, and in the groin area to help reduce his temperature. Be careful using very cold water as it can be counterproductive. Cooling too quickly or allowing the body temperature to become too low can cause other life-threatening medical conditions.
  • Increase air movement around him with the car fan or air conditioner.
  • Even if your dog appears to be recovering, take him to your veterinarian as soon as possible. He should still be examined since he may be dehydrated, have electrolyte abnormalities or other complications such as brain swelling, kidney failure and clotting problems.

While treatment can be effective, the survival rate for heat stroke is only 50%. Therefore, the best option is prevention, prevention, prevention.  So, what is a poor pooch or pooch owner to do on a hot day?

  • Provide access to fresh, clean water at all times.
  • Make sure outside dogs have access to shade, regardless of the changing position of the sun during the day.
  • On a hot day, restrict exercise.  Don't take your dog jogging with you. Exercising while the weather is very hot can be dangerous.
  • Pets with pre-existing conditions or breathing problems should be kept cool and in the shade.  Even normal activity for these pets can be harmful.
  • Avoid places like the beach, concrete or asphalt areas where heat is reflected and there is no access to shade.
  • Do not leave your pet in a hot, parked car even if you're in the shade or planning to be gone a short time. The temperature inside a parked car can quickly reach up to 140 degrees.
  • Do not muzzle your dog as this will limit his ability to pant.
  • Wetting your dog with cool water from a hose or allowing him to swim for exercise can help maintain a normal body temperature.  Several companies make cooling vests for dogs to wear during hot weather.
  • If you have a window air conditioner rather than central air, move your dog to a cool room of the house.  Air conditioning is one of the best ways to keep a dog cool.  Frozen water bottles or gel packs can also be placed under a layer of bedding.

We haven’t specifically addressed cats in this article for a couple of reasons.  First, because of their desert heritage, cats tend to be more heat tolerant than dogs.  Second, most cats are indoors and even those that are outside tend to find a shady or cool place to hunker down and remain quiet.  Finally, cats rarely feel the need to exercise, play excessively or make any attempt to please their owners. The only time heat stroke is a problem in cats is when they are accidently left in a hot car or they unknowingly get into the clothes dryer.

As with many things in life, common sense during a heat wave is the rule.  If it is too hot for you to go out and walk or play in a fur jacket, then it is too hot for your dog as well.