Car Safety for Pets: Temperatures Inside Cars and Restraints

A parked car can become dangerous for a pet in minutes, and a loose pet can be dangerous to everyone in a moving one. The AVMA names both as the two especially risky behaviors: leaving pets in vehicles and letting them ride loose. As of October 2026, its guidance says never to leave a pet alone in a parked vehicle, whatever the outdoor temperature or how long you expect to be gone.

1. How fast a car heats up

The AVMA says a vehicle can reach a temperature that puts a pet at risk of serious illness or death on a day that does not seem hot, even when the car is in the shade, and cracking the windows makes no difference. It cites research on vehicle safety for children, which shows these temperature rises inside a vehicle:

The AVMA's footnote says the rise is basically the same whether it is 70 or 110 degrees outside. A quick worked example using the table: on a 70°F day, 60 minutes adds 43°F, which gives about 113°F inside. The AVMA's own wording is "more than 110 degrees" for a 70-degree day. On a 90°F day, 20 minutes gives about 119°F. These sums simply add the table's rise to the outside temperature.

The ASPCA's hot-weather tips say the same thing in fewer words: never leave animals alone in a parked vehicle, because it can lead to fatal heat stroke and is illegal in several states.

2. Cold cars count too

The AVMA also says to remember cold weather. Leaving a pet in a vehicle on a chilly day is not much better than leaving it outdoors. Young, old, ill, or thin pets are particularly susceptible and should never be left in cold cars.

3. Why loose pets are a hazard

The AVMA lists several risks of unrestrained pets while driving:

• A small pet can crawl into the footwell and interfere with the brake or accelerator.
• A large pet leaning across your lap can block your view of the road.
• In a collision, an unrestrained pet may be crushed by deployed airbags or thrown out of or through windows or the windshield.

4. Pickup trucks and open windows

Riding loose in a pickup truck bed is dangerous and illegal in many states, according to the AVMA. Dogs can fall or jump out and be injured or killed on impact, or be hit by other traffic. A tether is not a fix, because it could tangle, injure, or even choke the dog. If a dog must ride in a truck bed, the AVMA says to use a secured, appropriately sized and ventilated kennel.

The AVMA also cautions against letting a dog hang its head out the window. Flying debris can injure the head, and an abrupt turn or stop could throw the dog out, or the dog could jump out.

5. How to restrain a pet in a car

First ask whether the pet needs to come along. The AVMA says that if the answer is no, leave the pet safely at home. If it does come, use an appropriate restraint:

• Vehicle harness (usually dogs only): this is different from a walking harness. The AVMA says to look for a crash-tested harness that works with the seat belt and keeps the dog sitting upright rather than lying down.
• Crate or carrier: pick one big enough for the pet to stand, turn around, and lie down comfortably. Place it as near to the center of the vehicle as possible and secure it so it cannot move.

6. Before you leave the car

1. Take the pet with you or leave it at home.
2. Lock in the harness or secure the crate before starting the engine.
3. Keep windows closed far enough that the pet cannot jump or lean out, given the AVMA's warning about dogs hanging their heads out.
4. Plan stops so no one has to leave an animal in the car.

7. Key takeaways

• The AVMA and the ASPCA both say never leave a pet alone in a parked vehicle, regardless of temperature or time.
• Interior temperature can rise 19°F in 10 minutes and 43°F in an hour.
• Shade and cracked windows do not make a parked car safe.
• Use a crash-tested harness or a secured, correctly sized crate.
• Pickup truck beds and head-out-the-window rides carry real injury risk.