The bad news for animal lovers Friday was that an industrial chemical was found in recalled pet food, but the worst news was that authorities still didn't know why hundreds of dogs and cats in North America fell ill or died.
The Food and Drug Administration said its tests of pet food made by Menu Foods Income Fund of Ontario, Canada, turned up melamine, a chemical used to make plastic, glue, fertilizer and paint. Scientists at Cornell University said they discovered the substance in the urine of sick cats and in the kidney of a cat that died after consuming some of the recalled food.
But it remained unclear exactly what caused pet illnesses and deaths that sparked this month's sweeping recall.
Last week, scientists at the New York State Food Laboratory and the New York State Animal Health Diagnostic Center at Cornell identified aminopterin, a substance found in rat poison, as the possible culprit. But the federal testing did not confirm the presence of aminopterin.
"There's little information in scientific literature on melamine exposure in dogs and cats, so it's very difficult to determine a level that would be harmful or lethal," Stephen Sundlof, director of the FDA's Center for Veterinary Medicine, said at a news conference.
Melamine, however, "should not be in pet food at any level," he added. He said the agency did not know how the melamine got into wheat gluten, an ingredient that is the focus of the FDA's investigation.
"It's awful. They don't seem to know," said Madeline Bernstein, president of the Society for the Prevention of Cruelty to Animals of Los Angeles. "Meantime, people are literally afraid to feed their pets."
Neither did the new findings soothe Jim Powers of Napa, Calif., who said his cat Amber was found to have acute kidney failure about two weeks ago. He said Amber, who is improving, had been eating Nutro brand cuts-and-gravy pouches for the last year.
"It makes me feel worse because I don't believe the chemical they found has anything to do with the sickness," said Powers, 58, a lab equipment salesman with a degree in biochemistry. "It's not a very toxic material as far as I can tell. I think the aminopterin is the real culprit. It's a very poisonous substance."
City of Industry-based Nutro Products Inc. said Thursday that its dry pet foods -- which constitute more than 90% of its products -- were not part of the recall and were safe.
