The maker of the recalled pet food, Menu Foods, of Ontario, Canada, has confirmed the deaths of only 16 pets.
Paul Pion, founder of the Veterinary Information Network, which counts 30,000 veterinarians and veterinary students as members, said Tuesday the number of reported kidney failure cases had already grown higher than the 471, but he said he wouldn't have an updated tally for a few days.
Of the reported cases, he said, 104 animals have died. The network's survey results were earlier reported by the Los Angeles Times.
Pion, a California veterinarian, said only 10 percent to 20 percent of the people who belong to his Web site had responded to a request for information.
"If we're only getting 10 percent of the veterinarians, you can do the math," he said.
Early Show resident veterinarian Dr. Debbye Turner said Wednesday, "Pretty much every vet you talk with has one or two cases."
She adds that another Web site, PetConnection.com declares nearly 2,000 pets have died from eating the recalled food.
So who is right? In short, Turner says, nobody really knows, and, "We don't know that some of the pets reported on PetConnection aren't some of the same pets reported on VIN or reported in other series."
The American Veterinary Medical Association told The Early Show, "The AVMA has not tracked the number of deaths and cannot verify reports coming from other organizations."
And Dr. Ann Hohenhaus of the Animal Medical Center in Manhattan told Turner, "I think that the worst should be past, because the recalled foods have been off the shelves since March 17. Everybody has gone through their kitchen cabinets and, I hope, taken all foods off the shelf."
Scientists at the New York State Food Laboratory last week in the scare that prompted the recall by Menu Foods of 95 brands of "cuts and gravy" style dog and cat food.
Some pets that ate the recalled brands suffered kidney failure, and the company has confirmed the deaths of 15 cats and one dog. Aminopterin, a derivative of folic acid that was once used to induce abortions and is now banned as a rodent poison in the United States, can cause kidney damage in dogs and cats.
Scientists so far have offered no theories on how aminopterin got into the products of Menu Foods, which makes pet food for most of North America's top retailers.
Researchers at the New York food lab, Cornell University and other labs were still working Tuesday to pinpoint which individual ingredients were tainted with the poison, officials said. They also said there could still be undetected hazards in the food.
Sam Bornstein, a spokesman for Menu Foods, said the company has not yet updated the number of confirmed pet deaths. He said testing to determine the source of the aminopterin and how it got into the food "is continuing aggressively" but Menu did not have any new results.
The company on March 16 recalled products packaged from Dec. 3 to March 6 and advised retailers last week to remove all the products from their shelves to verify the dates they were packaged. Products not made between those dates can still be sold.
The recall covered products carrying names of major brands including Iams, Nutro and Eukanuba. The food was distributed throughout the United States, Canada and Mexico by major retailers such as Wal-Mart, Kroger and Safeway.
The Food and Drug Administration has said the investigation was focused on the ingredient wheat gluten.
Testing has not been easy.
Wheat gluten has "been a real difficult sample to work with," said Daniel Rice, director of the New York food lab. "It's real sticky, gummy. If you can imagine wet flour and you're trying to get that into solution and put that into an instrument."
Veterinary Information Network provides a secure site where veterinarians share clinical information and other resources such as conference schedules and continuing education courses.