Even with the windows rolled down on an 85 degree day, the temperature inside a car can rise to 102 degrees in just 10 minutes. Within 30 minutes, the interior can reach 120 degrees, said Siskiyou Humane Society's shelter manager Kim Latos, who urged animal owners to never leave their pets inside a car.

"We know people love their dogs, or they wouldn't have them with them," said Latos. "But they need to look at the facts. Leaving dogs in a car, even with the windows rolled halfway down, can be deadly."

Parking in the shade is not the answer, either, because shade can move throughout the day, she said.

"Most owners are very defensive when we question them about leaving their dogs, or other animals, inside their vehicles, ," Pierce said. "But they can receive a citation, and officers are authorized to get the animals out by any means necessary."

Two weeks ago, Pierce said he wrote a citation to a man who forgot his dogs were inside his van while he ran inside to see about getting a haircut.

"The barber said they could get him in right then, and he was inside for about 45 minutes," Pierce said. "Dogs don't have sweat glands, and they pant to cool themselves down. But they need water, and these dogs didn't have any."

Pierce said dogs try to find their own ways to cool off when overcome by heat. Some may crawl down onto the floorboards or beneath the seats where they can't be seen.

According to Pierce, who is only a part time Animal Control officer, he gets two or three calls every week about dogs left inside hot cars, but believes it happens a lot more often than that.

What to do if you see an animal in distress

• Call the police department or 911 if you see a dog locked inside a hot car.

• If an animal is overcome by heat, bring down their body temperature by soaking the animal in cool (not ice) water, but make sure the water doesn't get into the mouth or nose of an unconscious animal. Then seek immediate veterinary care.

• For more information, go to mydogiscool.com