Not even for a minute. Not even with the car running and air conditioner on. On a warm day, temperatures inside a vehicle can rise rapidly to dangerous levels. On an 85-degree day, for example, the temperature inside a car with the windows opened slightly can reach 102 degrees within 10 minutes. After 30 minutes, the temperature will reach 120 degrees. Your pet may suffer irreversible organ damage or die.
Watch the humidity
"It's important to remember that it's not just the ambient temperature but also the humidity that can affect your pet," says Dr. Barry Kellogg, VMD, of the Humane Society Veterinary Medical Association. "Animals pant to evaporate moisture from their lungs, which takes heat away from their body. If the humidity is too high, they are unable to cool themselves, and their temperature will skyrocket to dangerous levels—very quickly."
Limit exercise on hot days
Take care when exercising your pet. Adjust intensity and duration of exercise in accordance with the temperature. On very hot days, limit exercise to early morning or evening hours, and be especially careful with pets with white-colored ears, who are more susceptible to skin cancer, and short-nosed pets, who typically have difficulty breathing. Asphalt gets very hot and can burn your pet's paws, so walk your dog on the grass if possible. Always carry water with you to keep your dog from dehydrating.
Don't rely on a fan
Pets respond differently to heat than humans do. (Dogs, for instance, sweat primarily through their feet.) And fans don't cool off pets as effectively as they do people.
Provide ample shade and water
Any time your pet is outside, make sure he or she has protection from heat and sun and plenty of fresh, cold water. In heat waves, add ice to water when possible. Tree shade and tarps are ideal because they don't obstruct air flow. A doghouse does not provide relief from heat—in fact, it makes it worse.
Cool your pet inside and out
Whip up a batch of quick and easy DIY peanut butter popsicles for dogs. (You can use peanut butter or another favorite food.) And always provide water, whether your pets are inside or out with you.
Keep your pet from overheating indoors or out with a cooling body wrap, vest, or mat (such as the Keep Cool Mat). Soak these products in cool water, and they'll stay cool (but usually dry) for up to three days. If your dog doesn't find baths stressful, see if she enjoys a cooling soak.