How Dogs Cool Down

Staying cool in the summer is tough on people, but it’s especially difficult for dogs. Understanding the limitations of your dog’s natural cooling system is important. It enables you to better prepare and help safeguard him against a heat related illness (HRI), particularly if he’s exercising outside on a hot summer day.

Keeping cool is a complex process for dogs and it involves numerous body systems like the respiratory, cardiovascular, nervous and other systems.¹ These body systems work together to keep a dog’s core body temperature at an optimal range of between 99.5°F-102.5°F.² That range takes a lot of things into account like breed, size, weight, age, and condition. Proper hydration also plays a vital role in helping a dog’s body systems to regulate temperature.

Your dog’s core body temperature is influenced by what is scientifically referred to as heat inputs and heat outputs.

Heat inputs effect the amount of heat your dog’s body generates or absorbs and they can be internal or external. Examples include the metabolism of food, exercise intensity, and increased muscle or metabolic activity.³  The air temperature is an example of an external heat input. If the ambient temperature exceeds your dog’s body temperature, then he’ll begin to absorb heat from the environment.⁴

Heat outputs are how dogs dissipate heat. There are four ways their bodies release heat: radiation, convection, evaporation and conduction.

More than 70% of a dog’s body heat is dissipated through his body surface or skin.⁵ As your dog’s body temperature increases, the blood vessels in his skin dilate to increase blood flow. That enables heat to be lost from the blood. The body releases that heat from the skin into the environment.⁵

Heat loss through radiation becomes limited when the ambient temperature approaches or exceeds your dog’s body temperature. When the external temperature exceeds your dog’s body temperature, his ability to dissipate heat through the skin significantly diminishes.⁵

Dogs also dissipate heat through air or water moving across their skin.⁶ Water conducts heat away from the body much faster than air because it has a greater density and heat capacity.

The limitation of heat loss through convection is that cool breezes aren’t always prevalent in the heat of summer. And outdoor adventures with your dog may not always be near water.

Unlike humans, dogs lose minimal heat through sweating because they only perspire from their paw pads and nose. As the air temperature meets or exceeds your dog’s body temperature, he relies primarily on panting to cool down.⁴

Heat loss through evaporation is also limited. As the heat and humidity rise, panting becomes progressively less effective for dissipating body heat. When the relative humidity is greater than 80%, cooling down through panting becomes ineffective.⁵

When your dog lies on a cool surface such as a cold tile floor or a cool, shady patch of grass, his body heat transfers to the cooler surface through conduction.

The limitations of conduction, like convection, is the heat dissipation is dependent on a dog having access to a cooler surface.

• Be mindful of your dog’s normal environment vs. current environment. Slowly acclimate and condition him to exercising in rising outdoor temperatures.
• Enjoy summer activities with your dog in the cooler times of day like the morning or evening. Keep an eye on the air temperature and humidity. One rule of thumb is to avoid strenuous outside activities when the outdoor temperature plus humidity percentage exceeds 140. So if it’s 80°F with a humidity of 70%, that’s a total of 150 so take it easy outside with your dog and monitor him closely.
• Find ways to incorporate water into your summer outings. For example if you like to trail run or hike with your dog, seek out paths near water.
• Take regular breaks in cool, shady spots. Find areas to rest that have increased air circulation to get the most from summer breezes.
• Hydrate, hydrate, hydrate. A 44 lb. dog can lose between .5 and 1.5 gallons of water per day⁷ so they’ll need to drink at least that amount and preferably more during intense outdoor activities. Always have water on hand for your dog when exercising outside in the summer.
• Learn how to recognize the signs of heat related illness (HRI) and the steps to take if your dog overheats at Eukanuba.com/HRI.

Keeping dogs cool in the summer isn’t just important; it’s critical. A dog’s drive can often override his ability to realize he’s overheating. Dogs rely on us, as owners, to help keep them safe in the heat.

¹ https://www.akcchf.org/canine-health/sporting-field-dogs/hyperthermia-in-dogs-fast.html

² http://neacha.org/resources/Short%20Technical%20Report.pdf

³ https://www.vin.com/apputil/content/defaultadv1.aspx?id=7259207&pid=14365

⁴ https://www.extension.purdue.edu/extmedia/va/va-16-w.pdf

⁵ Bruchim Y, Horowitz M, Aroch I. Pathophysiology of heatstroke in dogs - revisited. Temperature (Austin). 2017;4(4):356-370. Published 2017 Oct 9. doi:10.1080/23328940.2017.1367457 (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5800390/)

⁶ https://todaysveterinarynurse.com/articles/providing-care-to-dogs-with-heatstroke/#:~:text=Heatstroke%20signs%20and%20symptoms%20include,%2C%20renal%2C%20and%20hepatic%20systems

⁷ https://www.workingdogmagazine.com/fueling-performance-keep-your-dog-hydrated/