Was it a test run? Did they mix poison into the wheat gluten and it was only by accident that it ended up in pet food instead of human food?
Nations pets may not be the only ones in danger,
"Either way presents disturbing scenarios. If the poisoning was accidental, it could indicate poor foreign controls over an ingredient wheat gluten that is used not only in pet food but also in many food products for humans. That this happened in China is no comfort when so many American food products and ingredients are imported. Thirteen percent of the wheat gluten used in the United States comes from China."
http://www.thenewstribune.com/opinion/story/6437657p-5736267c.html
My tinfoil hat theory is just this, but that it wasn't a test run but the real thing, since the poison did end up in the food supply. It's probably just bin-Murphy's Law that it ended up in the pet food supply instead of the human food supply.
-PJ