Dogs are incapable of sustaining prolonged heat and dehydrate much faster than humans do. Humans would tend to sweat to bring down their body temperature and try to keep their selves cool. It's a natural defense by the body to maintain itself. But you dog is incapable of controlling its body temperature and depend mostly on the environment to do so. Dogs do not perspire as humans do and thus a dog locked up for a long time in a hot care may die quite easily.
If you need to take out your dog with you and you are venturing into places which prohibit dogs and you know you will be at that location for more than 15 minutes. It is better to hire a dog sitter until you return. If you are in an area where you can monitor your car, example at the window in a diner having a snack, all you have to do is take out your valuables out your car and ensure that you park your car safely, wind down your windows and simply keep the dog strapped in its harness in the car.
Why People Do So
One would wonder why any dog owner would do such a thing to an animal they claim to love. The truth is that not all pet owners should be pet owners. They care little for the animal they should be caring for. There are plenty of dog owners with psychological problems and they will simply live out their problems through their pets. Whether it be beating the animal, tieing up and leaving the animal, starving or dehydrating the animal. While their are some people who take a dog not as a pet but as a subordinate. They have nothing or no one else to command around, beat or abuse so they find an animal to do so.
You cannot go places which you are likely to spend hours (mall shopping, hair dresser, barber shop etc) and have your pooch locked up in that hot car. If you do so, you should be charged for animal cruelty as this is nothing short of that. Your dog has feelings just like you and are susceptible to many things just like you. Take car of your dog and do not leave it locked up in your hot car.