Summer is far harder on dogs than we tend to think. A dog's body heats up surprisingly fast — even during a short bout of play, or simply standing in warm air, shade or no shade. Once we understand how a dog actually cools itself and where the limits of that lie, we can prevent many dangers before they ever happen.
Important note: this text is of a professional and informative nature and does not replace veterinary care. Every dog is an individual. At the slightest doubt, or at any sign of heatstroke, call your veterinarian at once.
Why a dog overheats faster than we do
We cool ourselves by sweating over the whole skin. A dog cannot — its sweat glands are only on the pads of its paws and its nose (Bruchim et al., 2006). For excess heat it has, in effect, no way out through the skin.
Its main cooling system is panting. As the dog draws air through an open mouth, moisture on the tongue and in the airways evaporates and cools the blood. But this is hard work and it has a limit: when heat and humidity are high at the same time, evaporation almost fails (Hemmelgarn and Gannon, 2013). That is exactly why humid days are more dangerous than dry heat.
The danger is not only in the sun
Many people think a dog is safe as long as it is in the shade. It is not. Heatstroke threatens in the shade too, and even during very brief activity.
Specialists distinguish two kinds of heatstroke. The first arises simply because the surroundings are too hot and poorly ventilated (Bruchim et al., 2006). The second arises from exertion — when a dog in motion produces more heat in its muscles than the body can shed (Flournoy et al., 2003).
And that is the trap: just a few minutes of play or training in the warmth can drive a dog's body temperature past a critical 40 to 41 °C, which begins to damage the organs (Bruchim et al., 2017). Shade does not help enough here, because the heat is generated inside the dog, not by the sun.
Why heatstroke is so dangerous
When a dog's body temperature crosses the critical threshold, the damage does not affect only one part of the body. The heat harms the intestinal wall, the liver, the kidneys and blood clotting all at once — often not immediately, but in the hours after the event. That is exactly why a dog that has overheated belongs at the vet even if it seems to have recovered. Organ failure is the most common cause of death in heatstroke, and it is precisely this that we are fighting when we act quickly (Bruchim et al., 2017; Bouchama and Knochel, 2002).
Every dog shows it in its own way
Some dogs endure more, others less. Especially vulnerable are puppies, older dogs, dogs with a dense undercoat, and short-muzzled breeds, in which air moves through the airways with more difficulty (Hemmelgarn and Gannon, 2013).
A dog struggling with heat tells us so with its body:
- heavy, rapid panting with a wide-open mouth
- the tongue stretched out and broadened more than usual, to increase the surface for cooling
- seeking cool ground to lie on
If we miss these signs, things can go downhill fast — to sticky, dark-red gums, staggering, absence, and in the worst case organ failure (Animavet, 2016). Then every minute counts, and the way leads straight to the vet.
How we protect the dog
The best protection is simply to adapt the day to the dog in the warm months.
Coolness indoors. On hot days a dog is safest in a closed, cooled or air-conditioned room. A lower air temperature lets it cool down without effort.
Let it find cold ground. If there is no air conditioning, the dog will find the coolest spot itself — tiles, deep shade, concrete. There it lies belly-down on the cold surface and gives off heat (Bouchama and Knochel, 2002). Let it reach such places freely, and do not disturb it while it rests.
Less movement. In the heat we cancel or greatly shorten play, running and long walks. We move activities to the early morning, when it is coolest, and keep them short.
In closing
A dog cannot tell us it is too hot — it tells us with its breath, its tongue, the way it seeks cold ground. Our task is to read these quiet signs and act before they turn dangerous. In summer that means less effort, more coolness and more attention. That way a hot day stays, for the dog, only a pleasant doze in the shade, and not a danger.
Literature and sources
Animavet (2016). Toplotni udar. animavet.si/toplotni-udar
Bouchama A., Knochel J. P. (2002). Heat stroke. New England Journal of Medicine, 346(25), 1978–1988.
Bruchim Y. in sod. (2006). Heat stroke in dogs: a retrospective study of 54 cases (1999–2004) and analysis of risk factors. Journal of Veterinary Internal Medicine, 20(1), 38–46.
Bruchim Y., Horowitz M., Aroch I. (2017). Pathophysiology of heatstroke in dogs – revisited. Comparative Exercise Physiology, 13(4), 211–225.
Flournoy S. W., Wohl J. S., Macintire D. K. (2003). Heatstroke in dogs: pathophysiology and predisposing factors. Compendium on Continuing Education for the Practicing Veterinarian, 25(6), 410–418.
Hemmelgarn C., Gannon K. (2013). Heatstroke: pathophysiology, clinical signs, and initial management. Veterinary Medicine: Research and Reports, 4, 55–63.