A local woman is leading the fight against the manufacturer of a popular dog treat that may have killed her beloved sheltie.

NEWS9 has learned that she's one of several people in the Pittsburgh area who said their dog died after eating chicken jerky treats made in China.

You may have heard about the FDA warnings. For some unknown reason, dogs were getting sick and even dying after eating chicken jerky dog treats made in China, something that has been happening for more than a year.

Now, there are many more people who claim their dogs died after eating these popular treats, which can be found just about anywhere pet food is sold, and they're suing the manufacturer.

In the lawsuit, they say the chicken jerky treats weren't "wholesome and delicious," as the manufacturer claimed. Instead they say they were "dangerous," even "deadly."

Lisa Mazur, of Natrona Heights, shared her story in her lawyer's office. Lisa said her dog, Riley, became deathly ill after she fed him Milo's Kitchen chicken jerky treats. She rushed him to her local vet, but there was little her vet could do.

"I answered my cellphone and she told me I had to put him to sleep," said Mazur.

But Mazur wasn't willing to accept that, so she took Riley to the Pittsburgh Veterinary Specialty and Emergency Center.

"He was in kidney failure, which was totally shocking," said Mazur.

After several days in intensive care, there was no improvement.

"He didn't even look right. Very sad-looking, and we had to put him to sleep. Just like that, from Wednesday to Sunday, we lost him," said Mazur.

Riley was a happy, healthy 7-year-old sheltie when he got sick, with no history of kidney problems. Mazur is now suing Del Monte, the manufacturer.

We got a copy of the class action lawsuit. Her story is front and center in the case that claims the treats were "unsafe, defective" and "dangerous."

In 2007, 2008 and again in 2012, the FDA issued warnings about chicken jerky treats made in China, but there were no recalls because scientists couldn't detect anything harmful.

The FDA even inspected the Chinese manufacturing plants.

"We have not yet identified specifically what the toxin is that's causing this, but it seems to affect the kidneys and cause acute renal failure," said Dr. Kenton Rexford, a specialist in emergency veterinary medicine at Pittsburgh Veterinary Specialty and Emergency Center.

New numbers show 3,243 reports of dogs getting sick, including 501 deaths. Most of the reports involve three brands: Milo's Kitchen, Waggin' Train and Canyon Creek Ranch.

In January, a lab detected trace amounts of antibiotics in the chicken jerky treats and those three brands issued a voluntary recall. The antibiotics are meant to keep chickens healthy, but they are not supposed to end up in food.

"We have to get to the bottom of this and I think recalls are the safest way," said Rexford.

Manufacturers such as Del Monte say, "There is no indication that the trace amounts of antibiotic residue are linked to the FDA's ongoing investigation."

Even a spokesperson for the FDA said, "These residues are highly unlikely to have caused the illnesses and deaths."

As for Lisa, she thinks the treats should have been recalled years ago.

"I don't want Riley to die in vain. I want people to remember him and the pain that he went through because I didn't know. And it's not fair that I didn't know," said Mazur.

The manufacturers, Del Monte and Nestle Purina, maintain the treats were safe.

We've also spoken to a woman in Carnegie who says her dog died after eating the treats. She and several other dog owners from Western Pennsylvania are joining the class action lawsuit.

Veterinarians say genetics may play a role in this mystery, and may be why some dogs get sick and others don't.

Since it's still unclear what's causing dogs to suddenly go into kidney failure, many veterinarians recommend staying away from any dog treats that are made in China.