The pet food contamination case isn’t closed yet. On April 6, FDA’s director, Center for Veterinary Medicine, Stephen Sundlof told CNN news that “somebody may have added melamine to the wheat gluten in order to increase what appears to be the protein level.” Higher protein levels in wheat gluten command a higher market price. FDA is not sure whether melamine is the causative agent of the sickened animals, but has found it useful as a marker in tracing the contaminated products. Other animal protection groups have suggested causes such as extreme amounts of Vitamin D or small amounts of rodenticides. The FDA, however, has received more than 12,000 complaints of sickened pets during three weeks of dog and cat food product recalls.

In postmortems conducted for Menu Foods, one of the affected processors, Cornell University scientists found melamine in the urine and kidneys of deceased cats who participated in a taste test for the processor. Since then, Menu Foods extended the recall of all products manufactured between November 8, 2006 and March 6, 2007, which used wheat gluten containing melamine purchased from supplier ChemNutra of Las Vegas, NV. ChemNutra imported wheat gluten from Xuzhou Anying Biologic Technology Development Company in Wangdien, China, and has recalled any remaining wheat gluten at distributors and processors.

 “The wheat gluten ChemNutra recalled was all shipped from China in 25 kg paper bags and distributed to customers in the same unopened bags,” ChemNutra stated in a public notice. “Each ChemNutra shipment had the certificate of analysis information from the supplier, including batch number and the supplier’s content analysis and test results.” According to ChemNutra, the 792 metric tons of gluten was shipped only to distributors and manufacturers making pet food.

Barring any mercenary or criminal intent in the supply chain, one issue remains: were there any chemical analysis tests performed by ChemNutra on the incoming wheat gluten before shipping it to customers? Had any of the processors performed tests, or did they accept the original’s Chinese supplier’s test results?