BOSTON (CBS) — As Memorial Day weekend marks the unofficial start to summer, many pet owners will be hitting the roads.

Dr. Edward Schettino, Director of Veterinary Medical Services at the Animal Rescue League of Boston, advises travelers bringing their furry companions along to plan accordingly and not leave them alone in the hot weather inside or outside the car at any time.

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Rule of thumb:  “Plan for your pet as you would plan for yourself.”

“You need to make sure that you have the proper itinerary where you are able to stop, take your pet out of the car,” he said. “Have your pet take a walk, fresh water, fresh food. Also planning your trip where you’re not leaving your pet in your car unattended – it is very, very important,” he said.

Leaving pets unattended in a vehicle is the most common cause of deadly heat strokes among pets, according to Schettino. Even when outdoor temperatures are just 70 degrees, it can get as high as 100 in a car in a matter of minutes.  Even if the windows are open “just a little bit,” he said.

“Pets do not sweat the way people do to alleviate the heat, they can’t get out,” Schettino said.

“People believe that they are doing nothing wrong. They are running inside the shop getting a coffee. The weather is nice outside it is 60, 70, or 80 degrees; they don’t feel hot, their pets are out with them for the day. They feel that everything is wonderful. They go inside the store — they are delayed and they come back to a fatal experience, which is bad” he said.

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In August of 2016, Gov. Charlie Baker signed a bill that protects pets left in hot cars and Good Samaritans who break them out to save them.

The fine can be up to $500 for anyone who neglect animals in hot cars. The law also places restrictions on owners leaving dogs tethered in extreme weather.

If a passerby happens to see an animal in a hot car, Schettino offers the following tips to help save a pet.

“First, they can look to see if the owner is around ask anybody that’s around: ‘Do you know who owns this car?’ If they are unable to find the person who owns that car or drives that car with the pet inside, they should contact the police department.  If the police department doesn’t respond and it’s a fatal situation, people can actually break into that car to save that pet’s life as long as they follow those steps.”

Schettino says when in doubt, leave your pet at home.

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“There’s plenty of people and services that can take care of your pet,” he said.