COLUMBIA, S.C. — The death of a police dog left in his handler's car in South Carolina is a reminder that hot cars can be as dangerous for the animals as chasing criminals.

At least three police dogs have died from heat stress inside vehicles so far in 2018 and that number is unofficial, because there is no requirement to report the deaths of police dogs to the government, said Catie Cryar, a spokeswoman for People for the Ethical Treatment of Animals.

The Officer Down Memorial Page lists three police dogs killed by gunfire this year.

Last year PETA counted 13 police dog heat deaths, Cryar said, while the website had seven dogs killed by gunfire and two stabbed to death.

"We appreciate these dogs and we need to make sure our actions show it," said James Hatch, who founded a group to protect police and military dogs after a K-9 saved his life during his last deployment as a Navy Seal.

Hatch's Spikes K9 Fund raises money for body armor to protect dogs, but also for heat alarms that start by sounding a horn and alerting a handler's cellphone when temperatures in a vehicle get dangerous for a dog and continue to escalate until eventually popping open the door so the dog can get out.

"Turbo," a Labrador mix owned by the Columbia Police Department, died in July after being left in a vehicle for more than six hours as his handler as at active shooter training at a high school. Master Police Officer David Hurt was suspended for five days without pay.

Hurt's vehicle had a heat alarm, but the officer turned it off, Police Chief Skip Holbrook said. Hurt had the air conditioner on for the dog, but also left his windows down on a day when forecasters said the high reached 94 degrees.

But the alarm should have been the last resort. Dog handlers should frequently check on their animals to let them use the bathroom or just make sure they are OK, Holbrook said.

"We found there was no reasonable explanation why he wouldn't be checking on the dog throughout the day," the police chief said

Holbrook said prosecutors reviewed what happened and decided not to file criminal charges because while Hurt showed terrible judgment, he was not criminally negligent. The chief said he didn't fire the officer because he felt like it was a "mistake of the heart" and not an ethical lapse.

Police officials did learn through the review that the department had two different policies — with different heat alarm temperatures and other handling instructions— for police dogs. Holbrook plans to combine the policies and have his explosive-detecting, drug and tracking dogs all under the same leadership and general training.

Hurt was devastated by Turbo's death. He had just been picked to be a dog handler after seven years on the force in January, and the 22-month-old dog was given to him after the department bought the animal, Holbrook said.

Hurt can never be a dog handler again as part of his punishment, the chief said.

"People are going to be really hard on him," Hatch said. "But he made a mistake."

Hatch's organization emphasizes constant, intensive training for dog handlers so the animals become a constant part of their lives and can be safely kept around people in all situations.

Heat alarms are good, but can't be the only solution, the former Navy Seal said.

"Technology fails," Hatch said. "We didn't go on any mission without a map."