Never leave your dog unattended in a car on a hot summer’s day, even in the shade. Dogs are only able to regulate their temperature through panting and through sweating between their toes. As the temperature increases in the car, their temperature regulation becomes less and less effective. They can very easily overheat and suffer from heatstroke, which can lead to organ failure and, in extreme cases, death. Dogs with flat noses e.g. bull dogs, are more susceptible to heatstroke.
For dogs to overheat they don’t necessarily need to be in a confined space. Long walks in the middle of the day with little shade should be avoided. Walks should be scheduled at the cooler times of the day i.e. in the early morning or late afternoon, to avoid the risk of overheating.