Pet food contaminated on purpose?

The contaminant blamed for killing scores of pets may have been added on purpose to falsely boost the apparent protein content, officials are now saying. The latest revelation in the pet food scare raises even more questions about the safety of the food supply, which includes rarely-inspected ingredients from dozens of countries. Even a month after the public learned of the tainted Chinese wheat gluten, American inspectors have yet to be invited into Chinese plants to investigate.