RICHMOND, Va. -- Government testing found a chemical used to make plastics in recalled pet food linked to the deaths of dogs and cats, officials said Friday. The Food and Drug Administration said it found melamine in samples of the Menu Foods pet food, as well as in wheat gluten used as an ingredient. Cornell University scientists also have found a chemical, also used as a fertilizer, in the urine of sick cats, as well as in the kidney of one cat that died after eating the company's wet food. Menu Foods recalled 60 million containers of cat and dog food earlier this month after animals died of kidney failure after eating the Canadian company's products. It is not clear how many pets may have been poisoned by the apparently contaminated food, although anecdotal reports suggest hundreds if not thousands have died. The FDA alone has received more than 8,000 complaints. The new finding comes a week after scientists at the New York State Food Laboratory identified a rat poison and cancer drug called aminopterin as the likely culprit. The recall involved nearly 100 brands of "cuts and gravy" style dog and cat food made by Menu Foods. The recall covered products carrying names of major brand-name and private-label products sold throughout North America. Company officials Friday would not provide updated numbers of pets sickened or killed by its contaminated product, though they said they've received more than 300,000 calls from consumers. Henderson said pet owners would be compensated for veterinary bills and the deaths of any dogs and cats linked to his company's products. PETA Wants Bigger Recall Meanwhile, animal rights advocates called on federal food safety regulators and pet food companies to expand the recall to include dry varieties, claiming it makes pets sick. The U.S. Food and Drug Administration said Thursday it had no plans to suggest a wider recall to pet food companies, and veterinarians said they have not seen a trend of animals becoming ill after eating dry pet food. The People for the Ethical Treatment of Animals plans to make the appeal Friday in Washington after it said it received complaints from pet owners who claim their animals suffered kidney failure after eating dry pet food. Norfolk, Va.-based PETA wants the FDA and the companies to extend the recall to foods that have received complaints, chemically test it and perform necropsies on the animals involved. It also wants companies prosecuted if the FDA's probe turns up wrongdoing. FDA spokeswoman Julie Zawisza said she did not know how many of the complaints the agency has received have concerned dry pet food. Officials at Ontario, Canada-based Menu Foods, which made the recalled pet food, did not immediately return a call seeking comment. Veterinarians aren't seeing a trend of pets getting sick off dry food, said Paul Pion, founder of the Veterinarian Information Network. He said since so many people use dry food, you would expect to see many more ill pets if the food was tainted. "I wouldn't put much credence in it, but it's not out of the realm of possibility," Pion said. The Veterinary Information Network reported Tuesday that at least 471 cases of pet kidney failure have been reported since the recall, and more than 100 pets have died. Menu Foods has confirmed 16 pet deaths.