In the presence of high humidity and poor ventilation, dogs suffer more than us humans, especially in particularly closed, overheated and poorly ventilated environments, such as a car stopped under the sun. This happens because the dogs they have a system of thermoregulation different from ours compared to humans: in other words, they maintain their internal temperature almost constant by exploiting different physiological mechanisms. First of all, the dog doesn’t sweat (it has glands that produce “sweat” only under the foot pads) but it disperses heat only through the mouthThe nose and partly the ears. For this reason, when it is very hot the dog increases its temperature considerably. respiratory rate (a physiological state called polypnea) and seeks contact with cool surfaces. Its response mechanism to high temperatures is less efficient than ours and therefore it can be subject to heat stroke: knowing the physiological mechanisms of our pets is important to avoid incorrect and sometimes harmful behaviors.
How Thermoregulation Works in Dogs
The dog, like man and other mammals, is an animal homeothermicthat is, capable of maintaining a constant body temperature regardless of the external temperature, but it does so with different strategies than ours. In general, organisms regulate thermal exchanges with the environment through four methods:
- evaporation of liquids (like we humans do with sweat);
- convectionthat is – to put it simply – the transfer of heat to the air;
- conduction of heat towards a colder body with which we are in direct contact;
- radiationor heat loss through the emission of infrared radiation.
If for us humans the main mechanism of heat dispersion is evaporation, in dogs the body cooling occurs for more than 70% by radiation and by convection and only partly by evaporation. The temperature is lowered through the accelerated breathing ratemechanism technically called polypnea. Warm air enters the mouth, passes over the moist surface of the tongue, cools and lowers the temperature first of the capillary system and then of the body.
The nose also has a structure that favors the loss and evaporation of water through the moist mucous membranes. When the heat is not excessive, the dog breathes through the nose and the air passes through the nasal mucosa and cools. When it is very hot, this mechanism is no longer sufficient and breathing at an accelerated rate and heat exchange through the mouth and tongue come into play. Furthermore, to take advantage of the conduction mechanism, dogs lie down on cold surfaces, maintaining contact with the belly with the cool floor.
In dogs there is no skin sweating and sweat glands apocrine, distributed throughout the body are have no thermoregulatory function, and emit substances that determine the characteristic “dog smell”. The sweat glands eccrine (i.e. those that in us humans produce sweat) in dogs are present only at the level of the pads and serve to keep them soft and moist.
How to protect your dog from the heat
To help our four-legged friends during the summer season, some precautions can be particularly useful. First of all, as also recommended by the Ministry of Health, the dog should not be clipped: the fur has a protective role from the sun’s rays and insulates from excessive heat. It is sufficient to remove excess fur with frequent brushing. Furthermore, it is advisable to let the animal rest in a place that has a temperature around 24 °C leaving at his disposal a bowl of fresh water. Outdoors, it is best to choose a shaded and ventilated area, and if necessary, refresh the animal with a wet cloth (but not frozen) at the level of the head and inguinal region. Walks in the sun during the hottest hours or stops in the car when it is very hot, especially under the sun, should be absolutely avoided. Finally, you can administer fresh foodbut not cold.
The risk of heat stroke in dogs
Dogs, even more than humans, can be subject to heat stroke, especially in the case of high environmental humidity. Just think that, according to a study conducted in 2004, it appears that 50% of dogs inside a car with a temperature inside the passenger compartment of 29 °C and a humidity of 80-90% They can survive for just 48 minutes. Leaving it in the car, under the summer sun puts our four-legged friend at serious risk of not surviving.
Dogs are very sensitive to both prolonged stays in hot, closed and poorly ventilated places, and to the increase in temperature at the change of season when it is more difficult for them to recover their strength after intense physical activity.
Some breeds with long, dark hair or very flat faces (brachycephalic breeds) are more susceptible to heat stroke than others. Excess fat in obese subjects also slows heat exchange with the outside. All dogs, regardless of breed, need some time to acclimatize to hot climates.
