To me, it seems redundant to have to write about this every year, but there are still people who can't grasp the concept of how quickly a dog can die when left in a vehicle on a hot day, even when the vehicle is parked in the shade with the windows rolled down.
One of the main reasons I think people have difficulty understanding this is due, in part, to our desire to anthropomorphize our dogs. This means that we humans tend to give our dogs human characteristics. This results in us comparing ourselves to our dogs in many situations, including being left in a hot car. If a human can sit in a hot vehicle in the sun with the windows down, then heck, a dog can too right? Wrong!
The reason humans can tolerate sitting in a hot vehicle better than dogs can is because we have a far more efficient thermoregulation system than dogs. This means we are able to cool down, even in hot weather, far better than dogs.
Humans stay cool in a variety of ways, one of which is sweating. The entire human body is covered in several million sweat glands that automatically regulate when and how we sweat. These sweat glands are the human body's main way of cooling itself. As perspiration evaporates from the skin, it absorbs a large amount of heat from the body through a liquid-to-gas exchange. The hotter it gets, the more you sweat and the more you cool down. Also, the higher the humidity, the more difficult it is for the sweat to evaporate which is why we feel uncomfortable and sticky on muggy days. This last point is incredibly important when it comes to our dogs.
Dogs are not designed the same way humans are when it comes to thermoregulation. Their bodies are covered in fur, not skin covered in millions of sweat glands. Dogs sweat through the pads of their feet. But an interesting fact is that the sweat glands on their feet were not designed as a part of their thermoregulation system, but rather to add traction. This means they sweat to get a better grip on slippery surfaces. Think about that for a moment!
A dog's main form of heat exchange (getting rid of body heat) is by panting. As a dog pants, it pulls in air from its environment into the moist areas of its upper respiratory tract. This increased airflow causes an increase in the evaporation of heat within the moisture of the dogs respiratory tract. In essence, it kind of works the same way perspiring does for us. But for dogs, it happens inside the body instead of outside. Additionally, when a dog pants, it expels hot moist air from its body.
Now then, knowing that a dog cools itself through panting - which entails inhaling air into its body to improve evaporation of moisture and expelling the hot, moist air from its body - what do you think happens to a dog when it is left in a hot vehicle with little or no air circulation and high humidity?
Let me explain. When a dog expels moist air from its lungs as it attempts to cool itself down through panting, it is actually creating a humid environment around itself. When this environment is a hot vehicle with no air circulation or proper ventilation, a dog's ability to cool itself diminishes even quicker because, just as humans experience on hot humid days, the humidity of the environment (which the dog creates by panting in a poorly ventilated area) prevents adequate evaporation of the moisture. So, this means a dog heats up even faster when it is panting in its self-created humid environment. It doesn't matter that you have parked in the shade with the windows slightly open. If there is inadequate ventilation and no fresh air, the dog is not able to use its panting to cause the evaporation of moisture to cool itself.
Capeesh?What does all this mean? It means, leave your dog at home! Don't leave it in the car on hot days, sunny days, cloudy days or humid days. Just don't do it!
Joan Klucha has been working with dogs for more than 15 years in obedience, tracking and behavioural rehabilitation. Contact her through her website k9kinship.com.
