PORTLAND, Ore. -- A Portland family dog's apparent death by rat poison has neighbors concerned, and veterinarians warning owners to keep an eye on their pets.

The Hefele family's 8-year-old chocolate lab Balou went with the family to Manzanita just before Christmas. The first night at the beach, Brian Hefele says he let Balou out and his dog didn't come back. Hefele found him dead on their property. He took Balou's body all the way back to Portland and to Dove Lewis Emergency Animal Hospital.

"When we took him to Dove Lewis after he had died, the vet technician had said based on symptoms he was showing he had probably died of rat poison," Hefele said.

Soon word got around to neighbors about Balou's strange, sudden death.

"Our neighbor got very emotional and she was shocked because she said her dog, the same thing had just happened to her dog in the last couple weeks," Hefele said. "So that's when we perked up our interests in terms of something might be going wrong."

News of the deaths spread on social media and community bulletin boards.

Four area veterinary offices on Portland's Westside tell us they're very aware of rumors, but cannot say whether dog deaths were caused by rat poison without a necropsy. They say there are so many kinds of poison, they all present different symptoms.

Whatever's going on, they say keep your dog on a leash, and if they do have unusual symptoms, get them to a vet quickly.

The veterinarians say rat poison takes a couple days to go through a dog's system, so the sooner you get them help, the better.