A Philadelphia police dog died after being accidentally left inside a patrol car for more than four hours with the windows up on a hot day, officials said.

When found shortly after 12:30 p.m., Woodrow, a 5-year-old German shepherd assigned to Officer Joseph Arrison of the Canine Unit, was already dead, police said.

Arrison, a 28-year veteran who has been in the Canine Unit for 15 years, has been temporarily reassigned pending the results of an investigation by the Internal Affairs Division, police said.

"It's a tragic, tragic incident, and the officer is devastated," said Capt. Alan Kurtz, who commands both the Canine and Mounted Units. The loss has deeply bothered Arrison, investigators said.

The accident occurred after Arrison and Woodrow finished their shifts about 8 a.m..

Arrison, 49, of Northeast Philadelphia, stopped at Canine Unit headquarters at the Police Academy to drop off his cruiser and transfer Woodrow from his compartment in the back of the police car to Arrison's personal car for the drive home.

Canine Unit officers are permitted to take their partners home and receive a stipend from the city for their care. Arrison routinely took Woodrow home after work, officials said.

Before moving the dog, however, Arrison stepped inside headquarters to complete some end-of-shift paperwork and have a cup of coffee. He left a short while later but forgot about Woodrow, who was still inside the cruiser, investigators said.

It was a warm day, topping out at 85 degrees. By the time Woodrow was spotted by another police officer, the temperature was already reaching 80.

The police car's windows were up, so the temperature inside the vehicle was well above that because of the searing sun, investigators said.

A necropsy indicated Woodrow died of heat exhaustion, according to police.

Kurtz, the Canine Unit commander, said Woodrow's death may spark changes within the unit. Kurtz said he was looking into the possibility of installing heat sensors inside Canine Unit vehicles that would automatically drop the windows slightly, start a fan, and set off the vehicle's siren when the temperature became excessive while a dog was inside.

Investigators said Arrison was stunned when contacted at home about Woodrow's death.

There are no plans for a departmental burial for Woodrow, Kurtz said.