There are some factors that can increase risk for your pet. Obese pets, brachiocephalic breeds (short nosed such as pugs and bulldogs) animals who are in a new environment and not acclimated to the heat / humidity and excessive exertion for a pet that is not accustomed to that lifestyle can all contribute. Any pet is at risk and pet owners should follow these simple guidelines. Never leave pets in a vehicle. Even a warm day can elevate the environment inside your vehicle to dangerous temperatures. Never leave pets unattended in a yard without access to a cool location / shade and plenty of cool water. Limit outside activity to evenings and early morning before temperatures reach their peak. If your pet does not typically receive daily exercise, limit your activity to cooler times of the day and short distances.
If your pet exhibits sudden collapse, excessive panting, unresponsiveness or excessive drooling / foaming at mouth after having exposure to the elements or activity seek medical attention. You can begin to cool your pet with towels soaked in cool water, and utilize air conditioning or an open car window to provide air flow during your travel. Receiving medical care and further treatments will provide the best outcome for your beloved companion.