Heatstroke in Dogs

Key points:

  1.  Heatstroke can cause central nervous system damage, circulatory collapse and even death.
  2. Many factors such as short noses (ie. Boxers and bulldogs), heart conditions and excess weight increase a dog’s risk of developing heatstroke.
  3. Dogs that are cooled before arriving at the clinic have a much better chance of survival.

This subject has become more prominent in the last few years because dogs are being used more and more for search and rescue (like Hurricane Katrina and 9/11) and the detection of drugs and explosives and for security and suspect apprehension.  These tasks have caused dogs to spend a lot of time in very hot areas such as Afghanistan and Iraq.  Heat issues are prevalent in these areas and heading these problems off is very important.

Heat stroke is a common concern here especially in the southern U.S.  Heat stress comes from exposure to a hot and humid environment (“classical” heat stroke), strenuous physical exercise (called exertional heat stroke) or a combination of both.  Mortality rates are high and range from 36% to 50%.  Treatment is expensive and complicated.  Under normal conditions, dogs lose more than 70% of their body heat due to radiation (through the skin) and convection (when the tummy comes in contact with a cool surface).  When the temperature rises, panting starts which allow heat loss through evaporation also.

Heatstroke has two types: Exertional occurs when a dog works or plays in an environment to which it is not acclimated.  We need to get a dog used to running or playing in the heat.  Overexertion needs to be avoided and hydration is important.  Humidity over 80% also limits the normal ways dogs throw off heat and can be a factor in heatstroke.  Nonexertional is caused by impairment of the dog’s ability to get rid of the heat due to a decrease in airflow, lack of shade or water or an increase in temperature or humidity.  In an enclosed area like a car, a dog has trouble cooling itself through convection or radiation.  Dogs tethered outside or left free to roam without access to water or shade can also get heatstroke.  If they have access to both, they usually don’t get heatstroke.  They can find the coolest area to lie down or he area with the most airflow in order to take advantage of the heat dissipating mechanisms.

Unfortunately, heatstroke can affect organ systems throughout the body including cardiac and respiratory, GI tract, the nervous system and the muscle and skeletal systems.  The treatment therefore is very complicated and it is important to identify the reason for the heatstroke…..How did it happen?  Does the dog have health problems that could make it worse?  Does the dog still seem normal?  and, What cooling efforts did the client make before arriving?  Dogs with heatstroke most commonly show: listlessness, collapse, hypersalivation, excessive panting, bloody diarrhea or vomiting. Treatment must be started as soon as possible and cooling the patient is the most important aspect of the initial emergency treatment of heatstroke.  You can start this before the dog is brought to the hospital.  Spray the dog with cool (not cold) water and drive to the hospital with the air conditioner on or with the windows open to generate a breeze.  This has been shown to really increase the chance of saving your dog’s life.  The use of cold water or ice is contraindicated because it doesn’t let the blood go to the surface and impairs heat loss.

Do you have any questions about heatstroke in dogs? Feel free to contact our Burbank veterinarian at Rainbow Veterinary Hospital today!


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