Imported ingredients used in recalled pet food may have been intentionally spiked with an industrial chemical to boost their apparent protein content, federal health officials suspect.

That’s one theory being pursued by the Food and Drug Administration as it investigates how the chemical, melamine, contaminated at least two ingredients used to make more than 100 brands of dog and cat foods.

So far, melamine’s been found in both wheat gluten and rice protein concentrate imported from China. Media reports from South Africa, where 30 dogs died, suggest a third pet food ingredient, corn gluten, used in that country also was contaminated with melamine. That tainted ingredient has not been found in the United States, the FDA said.

Chinese authorities have told the FDA that the wheat gluten was an industrial product not meant for pet food. Still, melamine can skew test results to make a product appear more protein-rich than it really is. That raises the possibility the contamination was deliberate. FDA investigators were awaiting visas that would allow them to visit the Chinese plants where the vegetable protein ingredients were produced.

The FDA and Agriculture Department also were investigating whether some pet food made by one of the five companies supplied by Wilbur-Ellis was diverted for use as hog feed after it was found unsuitable for pet consumption.

Read (AP via MSNBC)