Some 500 dogs and nine cats may have died after eating chicken jerky pet treats made in China, according to updated complaints logged by federal veterinary health officials.

A new tally of reports filed with the Food and Drug Administration shows the agency has received 2,674 reports of illness involving 3,243 dogs, including 501 deaths. The agency also has received reports of nine illnesses in cats, including one death, the FDA said.

That’s up from an estimated 2,200 reports of illness, 360 dog deaths and one cat death reported last summer. So far, though, FDA has not been able to confirm a link between the treats and the ailments.

The new figures come less than a week after two of the largest retailers of pet chicken jerky treats issued voluntary recalls of several popular brands after New York state agriculture officials detected unapproved antibiotics in the products.

Nestle Purina PetCare Co. recalled its popular Waggin’ Train and Canyon Creek Ranch brand dog treats, and Del Monte Corp. officials recalled their Milo’s Kitchen Chicken Jerky and Chicken Grillers home-style dog treats from shelves nationwide.

In addition, two more firms have recalled their treats as well, including Publix stores, which recalled its private brand Chicken Tenders Dog Chew Treats and IMS Pet Industries Inc., which withdrew its Cadet Brand Chicken Jerky Treats sold in the U.S.

The voluntary recalls effectively remove the pet treats from store shelves nationwide, but FDA officials say they still haven’t solved the mystery of what’s been making animals sick. They say tests by the New York State Department of Agriculture and Markets found trace amounts of antibiotic residue, but that the levels don’t pose a threat to animals or people.

“Based on the FDA’s review of the NYSDAM results, there is no evidence that raises health concerns, and these results are highly unlikely to be related to reports of illnesses FDA has received related to jerky pet treats,” the agency said in a statement.

The New York agriculture agency used a common test to detect chemical contaminants in foods, said Joe Morrissey, a department spokesman. They relied on liquid chromatography-tandem mass spectrometry, or LC-MS/MS. The tests revealed four antibiotics not approved for use in poultry in the U.S. and one antibiotic that may be used, but is limited to nearly undetectable limits in the finished product.

FDA officials will continue to investigate animal illnesses tied to jerky treats. Since 2007, the agency has warned consumers several times that jerky treats are not necessary for pet health and that eliminating them won’t harm animals.

The agency last spring inspected five Chinese plants that made jerky treats. Officials weren’t allowed to take samples for testing. Now, inspection reports released about the fifth site, Yantai Aska of Yantai, China, shows that plant officials falsified records regarding imports of glycerin, a key component in the jerky treats.

Officials with China’s regulatory agency, the General Administration of Quality Supervision, Inspection and Quarantine, or AQSIQ, suspended the firm’s export certificate as a result of the March 2012 inspection.

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