SEATTLE -- A family dog that was shot with a hunting arrow has died.

The Human Society is offering a $2,500 reward to find whoever shot the dog in Seattle's Wallingford neighborhood Tuesday night.

The dog, a 7-year-old mastiff named Conan, was hit in the chest. The arrow punctured part of his lung, the dog's owner told KIRO 7 Eyewitness News.

The dog underwent emergency surgery to remove the arrow, which just missed his heart. He had been expected to survive, but the family said Thursday morning that he had died.

SLIDESHOW: Dog Killed By Hunting Arrow

"At first, I thought maybe he got out and somebody shot him. But then I realized he'd been shot in our yard. It's pretty upsetting," said Liam O'Hara, the dog's owner, in an interview Wednesday night.

"From where the arrow was in the side of the house, it was pretty obvious someone had taken some time to find a way to shoot at them in their sleeping area," he said.

Anyone convicted in Seattle of the crime of animal cruelty could face a fine of up to $5,000, a year in prison, or both.

Animal Shelter officials asked anyone with information about the case to call 206-386-4288.