On a hot day, the temperature inside a vehicle can quickly rise to dangerous levels for pets left inside — even for ‘just a minute.’

Anyone who’s seen the wildly popular YouTube video of veterinarian Dr. Ernie Ward sitting in a car on a 95-degree day knows how quickly the inside of a vehicle can become dangerously hot.

After just 30 minutes the temperature inside the car reached 117°F (47°C).

And this wasn’t the Arizona desert. It was partially shaded coastal North Carolina, with all four windows cracked.

Veterinarians have been warning people for years about the dangers of leaving pets in a hot car, but this video struck a chord with many people. It’s been viewed millions of times online.

Ward thinks one reason the video was so popular is that it captures what an animal might feel while trapped in a car on a hot day.

“If you leave a child or a dog in a car, they can’t open the door, or let down the windows, or turn on the air conditioner. They’re just left there,” Ward says. “And that must be the most horrible feeling in the world.”

Ward did his experiment on a 90°F day. But even cooler days can be dangerous for pets locked inside vehicles.

A chart on the American Veterinary Medical Association’s website shows that on a 70°F day, the inside of a vehicle can reach almost 100°F in 20 minutes.

In addition to the general temperature inside cars, a recent study published in the journal Temperature showed that surfaces inside a vehicle can become even hotter.

Researchers found that when vehicles were parked in the sun for an hour on a 100°F day, the dashboards reached 157°F on average, steering wheels 127°F, and seats 123°F.

It wasn’t much cooler for vehicles parked in the shade either. Dashboard temperatures averaged 118°F after an hour, steering wheels 107°F, and seats 105°F.

Researchers chose an hour because that’s about the time it takes to get groceries.

But even shorter trips can be a recipe for disaster.

Ward says people who leave their pets in a vehicle while running errands often rationalize it with: “I’m just going to go in for a minute.”

But with the rapid temperature rise inside a car on a hot day, each minute is a race against the clock for your pet.

“It seems like you’re just going to run into the store and be out in 5 minutes,” says Ward. “But it’s never that simple or quick — 5 minutes turns into 15, and 15 could be the difference between life and death.”

Ward hopes people who have seen the video keep in mind the image of him sweltering in a car before they take their pet with them on a hot day.

He says the popularity of the video has also “emboldened many municipalities and even states to take action and enact protections for children and pets left in hot cars.”

The Animal Legal & Historical Center at Michigan State University reports that approximately 28 states have laws on the books pertaining to animals left unattended in vehicles.

Some of those laws make it illegal to leave an animal in a vehicle under dangerous conditions. Others protect people from being sued if they rescue an animal in danger inside a hot locked car by smashing the window.

In general, dogs are happiest between 68°F (20°C) and 86°F (30°C).

That’s the temperature range where their body doesn’t need to spend extra energy keeping warm or getting rid of heat. This is called the “thermo neutral zone.” However, it’s not an exact science.

This optimum range depends on the dog’s breed, thickness of its coat, and health. Dogs can acclimate to hotter or colder temperatures, but this usually takes about 60 days.

Above and below that “optimum” range, dogs have a variety of ways to stay warm or keep cool. But these methods only work if it’s not too hot or too cold.

If the air temperature is below a dog’s skin temperature, about 70 percent of their body’s heat loss occurs through the skin.

When the ambient temperature reaches 88°F, though, dogs no longer lose heat through their skin. At this point, they rely on evaporation to stay cool. In people, this means sweating. But not in dogs.

“Dogs can’t sweat, so they have to pant to lower their body temperature,” Ward says. “So if you put them in a hot car, they’re much more susceptible to heat stroke and heat injury.”

Ward also points out that because dogs can’t sweat, it makes them “more sensitive” to changes in heat than people.

Additional factors can also make panting less effective, such as when the humidity is higher or if a dog is in a confined space with poor ventilation.

Some dog breeds also struggle more in the heat, such as pugs, Boston terriers, and boxers — because of their distinctive short noses or flat faces.

“One of the purposes of the muzzle is to heat and cool the air coming into the body of the dog,” Ward explains. “So if you don’t have a long muzzle, you can’t heat or cool the air as efficiently.”

A dog’s health also affects how they respond to heat. Older dogs — like many older people — have a harder time in the heat.

Older dogs may also have other health conditions that interfere with their body’s ability to get rid of heat, including heart, liver, kidney, or upper respiratory problems.

“This makes them more susceptible to stressors such as heat,” Ward says.

He adds that owners of older dogs may not even be aware of additional health issues their pet may have started experiencing.

Overweight or obese dogs have a hard time staying cool as well, which isn’t a small number. The Association for Pet Obesity Prevention estimated that 56 percent of dogs and 60 percent of cats in the United States were overweight or obese in 2017.

Even if you never leave your dog in a hot car, it’s important to be mindful of your dog’s environment on warm days.

There are several types of heat-related illnesses they can get, ranging from heat stress to heat exhaustion, to the most severe — heat stroke.

For both dogs and people, they all happen when the body’s core temperature rises faster than the body can cool it off.

Dogs with heat stroke may show several signs such as:

  • excessive panting
  • increased salivating
  • depression
  • weakness
  • dizziness
  • vomiting
  • diarrhea

Heat stroke can affect many of the dog’s organs including the lungs, heart, kidneys, stomach, intestines, and brain. Even a dog’s blood clotting ability can be affected.

The University of Illinois College of Veterinary Medicine recommends that if you think your dog has heat stroke, cool the dog down with cool (not cold) water. Placing a fan near the dog can also speed cooling. Then call your veterinarian.

The vet will use other methods to continue to cool down your dog, such as giving them intravenous fluids. Vets will also try to reverse the damage done to the organs by the heat.

How well a dog recovers after heat stroke depends on how high the body temperature rose, as well as the health of the pet and how long it took to get treatment.

To prevent heat stroke in your dog, give them plenty of water throughout the summer. Let them take frequent breaks in the shade or air conditioning. Avoid exercising during the hottest times of the day. And keep an eye out for signs of heat stroke.

As for traveling in a car or truck with your pet during the summer, Ward is clear about this one: “If you can’t take your pet indoors with you when it’s warmer weather, they’re safer left at home.”