The Food and Drug Administration (FDA) has learned that more than 1,000 dogs have died - and at least three people have become ill - after eating certain brands of jerky pet treats, health officials said Friday.
Most of the pet snacks were imported from China and sold by numerous companies under various brands, New York Daily News reported.
But despite seven years of investigation and testing, the FDA still cannot identify what is tainting these jerky treats.
"The agency continues to caution pet owners that jerky pet treats are not required for a balanced diet, and encourage them to consult with their veterinarians, both prior to feeding treats and if they notice symptoms in their pets," the FDA said in a statement.
According to the agency, since 2007, owners of around 5,600 dogs and 24 cats have complained that their pets got sick after ingesting the treats.
Based on the FDA's reports, 60 percent of the cases were about gastrointestinal problems and liver disease and 30 percent showed signs of kidney failure. The remaining 10 percent involved symptoms of neurological and skin disease conditions.
And for the first time, complaints of humans being affected have surfaced. The three humans affected were two toddlers who accidentally ate the snacks and one adult who may have been munching on them, the FDA said.
Still, some Chinese dog treat manufacturers claim their products are safe. Luke Qin, the owner of a Shandong factory, even ate a duck jerky treat to prove his business's snacks are harmless, NBC reported.
"It's safe, no problem," Qin said. "Human standard. You can try eating."
In an effort to identify the contaminant in the pet treats, the FDA has conducted post-death examinations on 26 deceased dogs, according to the Daily News. Unfortunately, they could not uncover the source of the problem.
The FDA is teaming up with the Center for Disease Control to further investigate.
For pet owners who are unsure about the quality of treats given to their pets, the FDA recommends observing their pet's behavior, health officials wrote in the statement.
Usually, hours or days after eating the questionable treats, the pets will show signs of decreased physical activity and appetite, diarrhea, vomiting and an increase in water consumption.