More than a month since the major recall of dog and cat food in North America began, many key questions still remain unanswered.
On 16 March, Menu Foods, Inc. initiated a North American recall of dog and cat foods, prompted by pet owner complaints and by its own testing. Since then, a growing list of pet food manufacturers and brand names has been added to the recall list. The latest additions to the list include two pet foods produced by the Natural Balance Pet Foods from Pacoima, CA, USA, after the company has received reports from customers of animals vomiting and experiencing kidney problems. Other manufacturers participating voluntarily in the recall of pet food products include: Menu Foods, Hill’s Pet Nutrition, P&G Pet Care, Nestle Purina PetCare Company, Del Monte Pet Products, Sunshine Mills and Natural Balance Pet Foods. The list of recalls includes approximately 60 million cans of more than 100 brands of dog and cat foods. Meanwhile, pet owners continue to report that their animals are getting sick and dying from foods not included in the recall.
The latest figures compiled by the Veterinary Information Network (VIN), an online service for veterinary professionals, indicate that the number of dog and cat deaths linked to the contaminated pet foods is likely to be in the thousands and the number of sick pets to be more than 10,000.
According to the analysis by Banfield Pet Hospital, a U.S. chain of veterinary clinics, as many as 39,000 dogs and cats have been affected by eating tainted pet food. The estimate is based on analysis of its database linking 615 pet hospitals and clinics. Three out of every 10,000 dogs and cats that ate the contaminated product developed kidney failure. Banfield said the diagnosis of kidney failure in cats rose 30% during the three months when the contaminated pet food was sold.
The Food and Drugs Administration (FDA) in the USA has confirmed 16 deaths (15 cats and 1 dog) linked to the recalled pet foods so far, but it recognizes that there may be many more pet illnesses and deaths. It has received over 14,000 calls from pet owners and veterinarians who reported illnesses that may have been associated with the contaminated pet foods in the first four weeks of the recall — more than twice the number of complaints typically received in a year for all of the products the agency regulates.
Pet food recall and the deaths of potentially hundreds or even thousands of beloved pets, have already had a major impact on the pet food industry. In addition, it has also caused renewed concerns regarding human food safety. Currently, there is no evidence to suggest that the human food supply is affected, but the Centers for Disease Control and Prevention is monitoring the incidence of human illness, such as increased renal failure, that could indicate contamination of the human food supply.
What Is Known?
Initial investigation at the New York State Food Laboratory identified the rodent poison, aminopterin, as the likely culprit in the scare that prompted the recall. Aminopterin, a derivative of folic acid, was once used as a rodent poison to induce abortions, but is now banned in the United States.
However, after FDA’s Forensic Chemistry Center was unable to confirm these findings, aminopterin is no longer considered to have any role in the on-going recall. Further investigations by the FDA identified melamine as a new culprit in the pet foods and in the wheat gluten used as an ingredient. Subsequently, FDA’s field laboratories found melamine in over 130 pet food samples and wheat gluten examined. In addition, Cornell scientists identified melamine in the urine and kidneys of cats that were part of a taste-testing study conducted for Menu Foods.
Melamine is a nitrogen-containing substance that is used in industry as a binding agent, flame retardant and as part of a polymer in the manufacture of cooking utensils and plates. Melamine has additionally been used as a fertilizer in some parts of the world, but not in the USA. However, melamine has no approved use in human or animal food in the United States.
Wheat gluten is a mixture of two proteins obtained when wheat flour is washed to remove the starch. It is used as a filler and binder in wet-style, cuts-and-gravy-type pet food to provide a gelatinous consistency and to thicken pet food "gravy." It is also used in human food products as a stabilizer or thickener.
The distributor of the wheat gluten is identified as ChemNutra of Las Vegas, and the supplier as Xuzhou Anying Biologic Technology from China. However, Chinese officials have already dismissed any blame. "The poisoning of American pets has nothing to do with China," said a report on the official People’s Daily website. An initial investigation by the Chinese government determined that China had not exported tainted pet food ingredients to the USA and Canada, officials said.
The FDA on its own website also makes clear that it remains to be determined whether or not it is the melamine itself that is the culprit, or whether it is some other contaminant, which may be associated with the melamine. "While the levels we’ve found to date in both the finished pet food product and the wheat gluten are below what would be considered toxic in rodents, there is extremely little data in the scientific literature on melamine exposure in dogs and cats. Regardless, the association between melamine in the kidneys of cats that died and melamine in the food they consumed is undeniable," according to Stephen Sundlof, the Director of FDA Center for Veterinary Medicine.
The latest additions to the recall list include two pet food products by the Natural Balance Pet Foods, a pet food company from Pacoima, CA, USA, which does not use wheat gluten that was associated with melamine contamination. The source of the melamine in this case appears to be a rice protein concentrate. According to news reports, San Francisco-based company, Wilbur-Ellis, imported the rice protein concentrate from China and sold it to Natural Balance and four other pet food manufacturers.
What is Unknown?
Could any other ingredients used in pet food manufacture be contaminated?
How did melamine get into the pet foods, or into the contaminated ingredients (wheat gluten and rice protein concentrate)?
The published research literature on melamine presence in pet foods is scarce. However, Animal Science database contains a paper by Cattaneo & Ceriani (1988), which indicates that manufacturers may intentionally add melamine to meat and fish meals.
The present pet food scare seems to be limited to North America. However, in the age of globalization of the food supply, it is only matter of time when a similar incident may happen in some other part of the World. It is clear that new control measures are needed to ensure food safety, for both pets and humans.
1. Cattaneo, P. & Ceriani, L. (1988). Melamine in animal meals. Tecnicia Molitoria, 39: 28-32.