WASHINGTON - Imported ingredients used in recalled pet food may have been intentionally spiked with an industrial chemical to boost their apparent protein content, federal officials said Thursday.
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 food.
Melamine has been found in both wheat gluten and rice protein concentrate imported from China. Media reports from South Africa suggest that 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.
FDA investigators are awaiting visas that would allow them to visit the Chinese plants where the vegetable protein ingredients were produced.
"Melamine was found in all three of those - it would certainly lend credibility to the theory that it may be intentional. That will be one of the theories we will pursue when we get into the plants in China," said Stephen Sundlof, the FDA's chief veterinarian.
Chinese authorities have told the FDA that the wheat gluten was an industrial product not meant for pet food, Sundlof said. Still, melamine can skew test results to make a product appear more protein-rich than it really is, he added. That raises the possibility the contamination was deliberate.
Wilbur-Ellis Co., the U.S. importer of the tainted rice protein, said Thursday that it was recalling all the ingredient it had distributed to five U.S. pet food manufacturers. The San Francisco company urged its customers to recall any products on store shelves.
Two of those companies have done so: Natural Balance Pet Foods and Blue Buffalo Co.
Natural Balance, of Pacoima, Calif., announced a limited recall Monday of its Venison and Brown Rice canned and bagged dog foods, Venison and Brown Rice dog treats and Venison and Green Pea dry cat food.
Blue Buffalo, of Wilton, Conn., followed Thursday by recalling 5,044 bags of its Spa Select Kitten dry food. The company intercepted most of the kitten food before it reached distribution centers, co-founder Billy Bishop said.
FDA officials would not release the names of the other two manufacturers that Wilbur-Ellis supplied, citing its continuing investigation.