Heat Stroke
Everyone is familiar with the slogan ‘Dogs Die in Hot Cars’ but why does this actually happen? If we were left sat in a car with the windows left slightly open on a hot sunny day it is unlikely that in 20-30 minutes we would over heat and be close to death. Instead we would become flushed, start to sweat and feel a bit uncomfortable.
A dog’s temperature regulation system is very different to ours. Whereas we become flushed and sweat to cool down, sweating is an ineffective method of cooling in dogs; in fact dogs only have sweat glands in their paws. When we sweat we use the process of evaporation to cool down. As sweat evaporates from our skin it cools us, and when we become flushed blood comes to the surface of our skin and cools in turn cooling us down inside.
How dogs keep cool
Dogs also use evaporation to cool down, but this is done using their respiratory system and panting. Both our, and dogs thermostats’ are located in the brain and this thermostat keeps a healthy dogs temperature between 38.3-38.7C. When a dog becomes hot the thermostat sends messengers to different parts of the dog’s body to start the process of cooling down. This includes the cardiovascular system (heart) and the respiratory system (lungs). The dog’s heart begins to pump faster, and the dog starts to breathe faster and pant. His head and neck become extended to maximise the amount of cool air that can pass up the nose and warm air exhaled through the mouth. The tongue will become flushed and the process of evaporation is in action where the air passing over the tongue is cooling the blood in it. The saliva and moisture on the tongue begins to evaporate cooling the dog down. The dog may choose to drink water to help cool itself and move to a cooler shaded area.
A fit healthy dog that is able to carry out these processes for cooling down will usually be able to keep its thermostat between its normal temperature ranges. However, if the dog has a disease which affects the cooling process, such as congestive heart failure which affects the heart and lungs, things can rapidly go wrong. Also, certain types of dog breeds are not as efficient at cooling themselves down, such as the shorter nose breeds (boxers, bulldogs, pugs etc.). These breeds may be affected by the heat faster than the longer nose breeds. Overweight dogs and those with long coats and the elderly are also at greater risk.
Why Dogs Die in Hot Cars
As mentioned dogs use the process of evaporation when panting to cool themselves down. When we leave a dog locked in a car on a warm day the dog soon becomes hot and begins to pant to cool down. As the moisture evaporates from the dogs tongue it enters the dogs surrounding environment, in this case the air in the car.
This air becomes more and more moist until the process of evaporation is ineffective, as the air is so humid and damp. The dog is then using a lot of energy panting to cool down to no effect. The dog’s thermostat goes higher and higher until eventually the dog dies a particularly unpleasant death. Even if the car windows are left slightly open on a warm day it is unlikely there would be enough air movement to keep the air in the car cool, and remove the humid damp air.
Prevention of heat stroke
There are many things we can do as responsible dog owners to prevent heat stroke.
The car:
• Avoid taking your dog for long car journeys on hot days. If you have no choice and have to take your dog, ensure the car windows are open as far as it is safe to do so without the risk of your dog escaping. Alternatively put the air-conditioning on full and ensure that the car has cooled before you put your dog in it and start your journey.
• Take regular breaks where you get your dog out of the car and offer him fresh water. Leave the doors and windows of the car open to allow any humidity that has built up to disperse.
• NEVER EVER LEAVE YOUR DOG UNATTENDED IN THE CAR.
The walk:
• Don’t walk your dog during the hottest part of the day (12pm-2pm). Instead walk your dog either early in the morning before the heat of the day has built up or in the evening when the heat has died down.
• Walk your dog in shaded, wooded areas instead of open sunny fields or concrete paths.
• Carry a bottle of water with a sports lid on that can be squirted into its mouth and offer this frequently.