A KIRO 7 Consumer Investigation exposes a potentially deadly problem involving one of the most popular dog treats on the market.

Millions of dogs chew on the treats every day, and there's a good chance your pooch is one of them.

Consumer Investigator Wayne Havrelly discovered the danger.

These dog treats are called "Greenies." They're sold in stores everywhere.

But our investigation found Greenies and products like them can pose a real danger to dogs.

Matthew Balkman of Issaquah uses cheese to reward his dog "Beau."

He used to use Greenies, a doggie treat designed to clean teeth and freshen doggie breath.

"The dogs do like 'em. They're tasty; he liked eating them," Balkman said.

But last May, Beau acted started acting sluggish after eating one.

"He wasn't eating at all," Balkman said. "I took him to the vet, the vet monitored him for a day and said there was something obstructing his bowel, 'We need to go in and operate.'"

Dr. Jayne Jensen performed the operation and removed a large green lump from Beau's intestine.

"She handed it to me, asked me if I knew what this is, and I said, 'Yes, that's a Greenie,'" Balkman said.

The package says Greenies are "100 percent edible" but a company spokeswoman told us they are "85 percent digestible."

"That was not 85 percent digestible," Jensen said. "That was not digestible."

Constance Odle's dog Berkley is recovering from the same emergency surgery. But instead of a Greenie, a similar product was blocking the dogs intestine.

"At first, I thought he ate a piece of a toy and when the vet told me what it was, I felt terrible guilt because I was the one who gave it to him," Odle said.

MORE ON THIS STORY greenies.com

Berkley is the latest of several dogs Dr. Jennifer McBride has operated on after eating teeth cleaning products, mostly Greenies.

"We will see things in abdomens that will dissolve like bones and over time, they will dissolve and go away. But these are mostly indisolvable, so they tend to get stuck more often," McBride said.

Our investigation discovered the results are sometimes fatal.

"I tried to revive her," said Gilbert Wright.

Wright lost his prized show dog, "Pompey of the Desert" after feeding him a petite size greenies treat. He feels an overwhelming sense of guilt.

"And I will feel that ways for the rest of my life!" Wright said.

During our investigation we tracked down nine people who claim their dogs died after eating greenies. We passed that information on to the company.

A warning on the Greenies label says to make sure you're giving the right size Greenie for your breed of dog. It also cautions you to "monitor your dog to ensure the treat is adequately chewed".

"They don't chew. They don't even have the muscles to chew. I mean, we chew, we do that. Dogs don't do that," said Jensen.

"They also say on their Web site to avoid gulping or sloppy eating but heck people can't even train their children not to do that," said Gilbert Wright.

Company officials with Greenies declined our request for an on-camera interview.

They sent us a statement expressing sadness over all the dogs in our investigation. They say "millions of Greenies are sold and enjoyed by dogs, every week without incident."

And "though injurious incidents are rare, more often than not, the pet is not fed according to our feeding directions."

Gilbert Wright just got a new Pompey, but his heart will always be with the show champion original who won countless awards for agility.

Beau has recovered from surgery and Mathew Balkman feels lucky.

"I'm saddened for the people that have actually lost their pets because we came very close."

Vets say nearly all dog treats, chews and toys can make your pets sick.

They say it's important to keep a close eye on them.