The ASPCA reported their suspicions three days ago that aminopterin was an unlikely suspect in the pet food recall. Today in an FDA press conference, that agency announced the discovery of melamine
in food samples from the recall. Melamine is that stuff you find in durable plastic products and flame-retardant foam, among other products. Although it is not normally highly toxic, concentrations of this substance in high doses can affect the kidneys, especially in cats. While the FDA and other scientists continue their investigation, the SPCA advises that treatment for kidney failure continue.
Pet owners should continue to report deaths and severe illness related to the recalled foods to the FDA
FDA Recall FAQ
AVMA Recall Resources