Veterinary Toxicologists Question Whether High Levels of Melamine Found in Recalled Pet Foods Are Sp

[Note: All photos shown of cells provided by the Animal Health Laboratory at the University of Guelph]

A whirlwind of activity within the veterinary industry began March 16, 2007, when Menu Foods announced a recall of its “cuts and gravy” style pet food after nine cats died during a company taste test. Veterinary officials now believe that about 90 brands of food may have contained melamine, a plastic laminate traced to a shipment of wheat gluten from China, or its byproducts. Companies that contracted with Menu Foods to produce food from December through March initiated voluntary recalls and on March 30 and 31, 2007, Hill’s Pet Nutrition, Del Monte Foods, and Nestle Purina PetCare Co. recalled some products that contained contaminated wheat gluten. And on April 3, 2007, the importer of contaminated wheat gluten recalled the entire batch of product it received from the source in China. 


Updated information about the pet food recall and treatment options will be posted online by the AAHA, AVMA, ACVIM, FDA, and Menu Foods. Menu Foods released a statement on March 30, 2007, with reassurances about product safety while Hill’s Pet Nutrition, Del Monte Foods, and Nestle Purina PetCare Co. have published information about their recent recalls.

To date, the FDA – which does not require pre-market approval for pet foods – has received 10,000 calls from pet owners and veterinary professionals since the recall was announced on March 16, 2007. The FDA has confirmed 14 deaths but the Veterinary Information Network (VIN) has logged 471 cases of illness associated with the recall and veterinarians have reported 292 known outcomes with 104 deaths, said Paul Pion, DVM, DACVIM, founder.

In Canada, the Ontario VMA (OVMA) has seen 20 to 30 cats with clinical signs associated with the recall and the Animal Health Laboratory at the University of Guelph has conducted autopsies on five cats and seen three others with clinical pathology, said Brent Hoff, DVM, DVSc, a clinical pathologist and toxicologist. Hoff has not seen any dogs with clinical pathology associated with the recall or heard of any cases in Canada.

Hoff, who is working closely with the American Society for the Prevention of Cruelty to Animals (ASPCA) and veterinary professionals at labs throughout the United States, believes that this could be a species-specific sensitivity.

Clinical signs include acute renal failure with tubular necrosis in cases reported to the lab. “You can see crystals sitting in the tubules of the kidneys,” he said. Pictures of the crystals are available online and several photos are shown here. In Canada, veterinarians are reporting cases to the OVMA and can direct questions to the Animal Health Laboratory, Hoff said.

The FDA has analyzed about 100 tissue and blood samples since the investigation began, but veterinary experts are not sure what to expect because scientific information about melamine is limited.

Stephen Sundloff, DVM., PhD, director of the FDA’s Center for Veterinary Medicine, said he is not fully certain that melamine is the agent of death or the only contaminant in the food during a March 30 press conference. He added that a team of veterinarians, toxicologists, and nephrologists working on the case do not completely understand the effects melamine will have on pets. He did say that professionals have seen crystals form in urine and kidneys, and identified vast differences between normal distal tubules and those in cats that ate contaminated food.

Steven Hansen, DVM, a board-certified toxicologist and vice president for the ASPCA, said that “there is nothing clear to stand on that melamine causes kidney failure in cats” or dogs though published reports (from 1940) show that when consumed in high doses it causes rats and dogs to excrete crystals in their urine.

Due to results from ongoing research, Hansen believes that there is a species-specific sensitivity in cats. In other words, while the contaminated food might injure dogs that have existing kidney disease, it seems to have dire effects on cats. The different mechanism of action is similar to the way Easter lilies affect dogs versus cats. While Easter lily consumption can be fatal to cats it causes gastrointestinal irritation in dogs, he said. Similarly, Permetherin kills fleas on dogs and can cause seizure in cats.

Overall, however, the compound is known to be moderately toxic, said Hansen who compared it to table salt and said it had twice the toxicity of acetaminophen.

To err on the safe side, veterinarians are encouraging clients to bring pets in for evaluation and tests if there is a possibility that they consumed contaminated food.

Some pets that consumed recalled food may show no signs of illness while others will show signs of lethargy, decreased appetite, vomiting, diarrhea, as well as changes in water consumption and urination. Veterinarians are using blood and urine samples to identify kidney disease and radiographs and ultrasound examinations to eliminate other causes of kidney disease or illness.

On March 21, 2007, a lab identified Aminopterin as a contaminant in pet food produced by Menu Foods from December through March, an isolated finding that was widely publicized by media though veterinary toxicologists quietly doubted its validity.

Veterinary toxicologists identified melamine in wheat gluten on March 26 – after receiving information from a pet food manufacturer – and matched it with urine and kidney tissue from cats that died during a Menu Foods feeding trial, said Donald Smith, DVM, DACVS, dean of Cornell University College of Veterinary Medicine, who joined Sundloff at the press conference. The Diagnostic Lab at Cornell is working with veterinary labs at the Universities of Guelph and Pennsylvania. In addition, 400 FDA employees at 20 district offices are involved in the investigation.

Although officials said that they would be reviewing inspection protocols, FDA professionals said they did not think that the melamine would have been identified in a routine inspection. A full list of the Menu Foods recalled products is available online and AAHA published a question and answer document that is also available online. Details on all of the pet food recalls are posted on the FDA website at

  1. Pet owners are encouraged to report illness associated with contaminated pet food and to visit the FDA website with the following information:
  2. Brand name, variety and lot numbers for the pet food fed to the dog or cat when it was ill
  3. If the pet received veterinary treatment, provide the name, address, and telephone number of attending veterinarian
  4. Date illness first noticed
  5. Signs/symptoms displayed
  6. Veterinary reports/records