With the dog days of summer around the corner, discovering how dogs cool down in the heat is important so to raise awareness about the risks of heatstroke in dogs. Hyperthermia (high temperature) takes place when the dog’s internal temperature reaches abnormally high levels which can quickly kill a dog if measures to cool the dog down aren’t taken promptly. One of the most common heat-related killers of dogs is being left in a car where temperatures can easily skyrocket in a matter of minutes, but there are other risks too such as exercising in exceedingly hot, humid weather. Dogs who are old, obese, have short noses or thick coats or dogs who suffer from underlying heart disease, respiratory disorders or neurological conditions are more likely to suffer heat stroke as these conditions decrease their ability to cool down. Knowledge is ultimately power when it comes to understanding how dogs cool down in the summer heat.
A Matter of Homeostasis
Our bodies and the bodies of our dogs are designed in such a way as to efficiently maintain an ideal internal core temperature. For sake of comparison,we can compare this ability to the function of a thermostat with a gauge that ensures the interior temperature of a home stays at a constant level.
Just like a thermostat, the internal temperature of our dog’s body is constantly monitored, but instead of a gauge, the anterior hypothalamus (the dog’s official thermo-regulatory center) helps maintain the body temperature within a certain range.
Should the dog’s temperature drop, measures take place so that the dog is warmed up, and should the temperature rise, measures take place so that the dog is cooled down.
The ability of the body to take measures so to return to its ideal internal core temperature is known as “thermoregulation” while the maintenance of the internal temperature is known as “homeostasis.”
A dog’s body therefore maintains itself in a state of homeostasis when it’s kept within its normal temperature range of 101 to 102.5 degrees Fahrenheit. An increase of the dog’s internal temperature can be due to the presence of a fever (pyrogenic hyperthermia) or exposure to external heat (non-pyrogenic hyperthermia) as seen when dogs are exposed to hot environments.
Four Ways Dogs Cool Down
Fortunately, dogs can cool down in several ways when it’s hot outside. We mostly think dogs cool down by panting, but they actually can also cool down in other ways. Acknowledging these other ways dogs can cool down can help dog owners and trainers better understand signs of problems, the importance of prompt treatment and how to prevent dogs from overheating in the first place.
Cooling Down Through Evaporation
When we think of a dog that feels hot, we often think of a dog that is actively panting so to cool down. With the mouth open, long tongue hanging down and loud, rapid breathing, the dog uses evaporation as his main way of quickly cooling down.
Dogs, like other animals covered by fur have limited ability to sweat, (they have only a few sweat glands on their feet but these are mostly meant to increase friction and enhance grip) so panting remains their primary method to cool down by increasing the evaporation of water across the moist surfaces of their mouth and tongue.
Since blood flows through the mouth and tongue, once the blood cools down, it reaches the rest of the dog’s body and thus, lowers the dog’s core temperature.
While panting can be effective when surrounding temperatures reach 89.6 degrees, it becomes much less efficient when there are high levels of humidity (consider that at humidity levels greater than 80 percent, panting is no longer efficient).
Did you know? According to Dukes’ Physiology of Domestic Animals, when dogs pant, their breathing increases to about 200 to 400 breaths per minute. That’s a whole lot considering that normal breathing rate in dogs is 30 to 40 breaths per minute!
Cooling Down Through Conduction
Conduction takes place when heat is transferred from one object to another.
In this case, the dog seeks out contact with a cool surface. Rover didn’t have to take a special class to learn what’s best for him when you find him lying down flat, in the Superman position, on a cool tiled floor during those dog days of summer.
Since most dogs have sparsely distributed hairs on their tummies, direct tummy contact is a fast way to effectively cool down.
Here’s a summer tip if you want to make your dog extra happy: provide him access to a tiled area such as the bathroom or kitchen, or if your dog loves the outdoors, let him dig a cool spot under the shade to sleep in.
Cooling Down Through Convection 
Convection involves contact with air movement to help speed up loss of heat. When Rover sticks his head out of the car window on a hot summer day, he may be doing more than satisfying his senses.
Chances are, he enjoys the sensation of air flowing through his coat and deep inside he instinctively knows that’s another good way to cool down from the summer heat.
Dogs also seem to know that strategically placing themselves in front a fan or AC or lying down besides the door, grants them access to some cool cross breezes that can feel refreshing.
These strategies ultimately helps the dog transfer the heat from his body to the air.
In the next paragraphs, we will see how convection along with evaporation is one of the best ways to cool down dogs in a case of hyperthermia.
Cooling Down Through Radiation
Finally, dogs can cool down through radiation which takes place when the dog’s body heat dissipates into the environment.
Basically, courtesy of blood circulation, the dog’s blood vessels will dilate so the excess heat is carried away from the interior of the body towards the exterior surface causing an elevation of the dog’s skin temperature.
This way, the hot blood is brought closer to the surface radiating the dog’s internal body heat into the environment.
While this can technically be an effective means of thermoregulation, problems start when the surrounding environment reaches the same temperature as the body, preventing the dog from cooling down.
” More than 70% of the total body heat loss in dogs is dissipated through radiation and convection from body surfaces. As the environmental temperature increases, approaching body temperature, evaporation, primarily through panting, becomes more important in maintaining normothermia.”~ Dr. Yaron Bruchim
Importance of First Aid
As seen, even though the dog’s body will take steps to prevent heat stroke, sometimes things don’t go as they should.
Dogs suffering from heat stroke will breathe rapidly, show pin-point bleeding on the skin (petechiae), blood in their vomit and/or stools, thick saliva, red or pale gums, and show signs of shock, disorientation or seizures.
Knowing what to do if you suspect heat stroke in your dog is of paramount importance as treatment should be initiated as early as making that phone call to the vet to tell him you’re on your way.
According to a study carried out by Drobatz KJ and Macintire DK, the prognosis was significantly better when dogs were actively cooled down before arriving at the hospital. These dogs had a lower mortality rate (19%) compared to dogs that weren’t cooled prior to arrival (49%). According to Today’s Veterinary Practice, an effective cooling method combines evaporative and convective cooling and entails applying cool or tepid water (avoid ice) to the dog’s skin while directing a fan towards the dog.
According to Vet Learn Compendium after applying cool water, while driving towards the hospital, evaporation can be attained by opening the windows or using the car’s AC. Cooling efforts on route to the vet should be stopped once the dog’s body temperature reaches 103.5°F to 104°F (have a helper check it every 5 minutes) so to avoid rebound hypothermia.
An Ounce of Prevention
An ounce of prevention is worth a pound of cure, the saying goes. Heat stroke can be prevented by taking a few safety precautions when the dog days of summer are in full swing. Here are few tips to prevent heat stroke in dogs:
- Ensure that outdoor dogs have always access to shade and drinking water
- Avoid exercising dogs on hot, humid days.
- Pick the cooler periods of the day for walks and training such as early morning or late evening.
- Leaving dogs alone in closed vehicles is like putting them in an oven and leaving them to bake.
- If you recently moved to a warmer climate, give your dog up to 2 months to acclimate.
- If your dog has been panting a lot, remember to provide fresh water to help him compensate for the evaporation.
- Consider that dogs prone to stress or who get hyped-up easily tend to overheat more quickly compared to calmer dogs.
- Avoid plastic crates that restrict air-flow.
- See your vet even though your dog seems to be recovering from hyperthermia. There are serious complications that may set in even if your dog seems to be feeling better.
Disclaimer: this article is not intended to be used a substitute for professional veterinary advice. If you suspect your dog has heat stroke, consult with your vet at once and follow his recommendations.
References:
- Epstein, Y. and Roberts, W.O.: The pathophysiology of Heat stroke: An integrative view on the final common pathway. Scand. J. Med. Sci. Sports. 21: 742-748, 2011. 4.
- Reiniker, A. and Mann, F.M.: Understanding and treating heat stroke. Vet. Med. 4: 344-355, 2002.
- Flournoy, S.W., Wohl, J.S. and Macintire, D.K.: Heatstroke in dogs: pathophysiology and predisposing factors. Comp. Cont. Educ. Pract. Vet. 25: 410-418, 2003.
- Canine Heatstroke Bruchim, Y. Koret School of Veterinary Medicine, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel.
- Dukes’ Physiology of Domestic Animals, 12th Edition 12th Edition, by
- Drobatz KJ, Macintire DK. Heat-induced illness in dogs: 42 cases (1976-1993). JAVMA 1996; 209(11):1894-1899.
- Today’s Veterinary Practice, Today’s Technician: Heatstroke in Dogs, retrieved from the web on June 17th, 2016