Scientists at Cornell University's College of Veterinary Medicine may have found a second contaminant in the wheat gluten used to make the tainted pet food blamed for the deaths and illnesses of scores of cats and dogs across North America, the Pittsburgh Tribune-Review reported.
Scientists also say they may have found this second -- unknown -- contaminant in the urine of infected animals.
"The concerted effort now is to identify what else is in there, and what's in the 'crystals of infected animals' urine and tissue," Dr. Richard Goldstein, associate professor of medicine at Cornell University's College of Veterinary Medicine, told the Tribune-Review.
The Food and Drug Administration has reported the wheat gluten -- imported from China -- is tainted with high amounts of the chemical melamine, commonly used in plastics.
Goldstein told the paper his researchers have ruled out aminopterin -- a rat poison -- as the source of the contamination. New York officials earlier said they discovered that toxin in the tainted pet food.
China Dragging Its Feet
The Tribune-Review also quoted an FDA source saying that China is slowing the investigation of the nationwide pet food recall.
Menu Foods recalled 60 million containers of wet pet food in March after dogs and cats across the country started to become sick and die after eating the food. The recall expanded in recent weeks to include nearly 100 brands of pet food and treats made with melamine-tainted wheat gluten imported from the Chinese company Xuzhou Anying Biologic Technology Development, Co. Ltd.
An FDA official told the Tribune-Review that he asked the Chinese government to help investigate the tainted wheat gluten. But the Chinese government's response, he said, has been slow and incomplete. Chinese officials have previously promised to cooperate with the investigation.
The FDA is now screening all wheat gluten imported from China and the Netherlands and seizing all wheat gluten from Xuzhou Anying.
Melamine Effects Unclear
In the meantime, the FDA and other researchers still aren't certain the high amounts of melamine made the animals sick.
More than 10 laboratories are researching the crystals found in the infected animals and are working together to develop criteria to determine which kidney illnesses were caused by the contaminated pet food, according to the Tribune-Review.
The labs will test urine and tissue samples from pets suspected of becoming ill from the food and possibly samples of the food, Dr. Goldstein told the paper. Pet owners and veterinarians, he said, are advised to keep samples of tissues, urine, and pet food.
The animal rights group, People For The Ethical Treatment of Animals (PETA), previously said that excessive amounts of vitamin D in pet food might be the cause of the growing number of kidney problems and deaths in cats and dogs across the country.
PETA's Vice President Bruce Friedrich -- citing laboratory evidence -- urged the FDA to refocus its investigation beyond wheat gluten and consider other possible contaminants in the pet food.
In his letter to Dr. Stephen Sundlof, director of the FDA's Center for Veterinarian Medicine, Friedrich said: "Wheat gluten is used almost exclusively in wet foods. However, the mounting number of complaints of illness and death in cats and dogs who had eaten only dry food strongly suggests that there is a second source of the poisoning, another toxic ingredient.
"Evidence from reputable laboratories indicates that an as yet unnamed ingredient may be to blame, perhaps a form of vitamin D."
Friedrich cited the following examples to illustrate his contention:
• A manufacturing error last year in the production of Royal Canin pet food resulted in excessive amounts of vitamin D3 in the food. This caused hypercalcemia, an abnormally high level of calcium in the blood that caused animals' kidneys to malfunction;
• Research in endocrinology at Cleveland Clinic has confirmed that high levels of vitamin D3 in animals' blood causes kidney malfunction;
• Symptoms associated with excessive vitamin D3 appear identical to the symptoms now being reported in dogs and cats.
This has led "us to believe that this vitamin may be implicated in this new horror," Friedrich told the FDA.
