- BHT, BHA, and ethoxyquin
These are chemical preservatives which are very effective at preserving dry cat food, but are suspected to be potentially cancer-causing agents. In recent years, many pet food manufacturers have moved toward using more "natural" preservatives, such as Vitamins C and E.
- Meat By-Products
The AAFCO (American Association of Feed Control Officers) defines meat by-products as " The non-rendered, clean parts, other than meat, derived from slaughtered mammals. It includes, but is not limited to, lungs, spleen, kidneys, brain, livers, blood, bone, partially defatted low-temperature fatty tissue and stomachs and intestines freed of their contents. It does not include hair, horns, teeth and hooves." Besides the fact that you don't know what species of animal the "meat" comes from, by-products as a rule are considered an inferior form of the protein which cats need.
- Meat Meal, Meat By-Product Meal
"Meal" is generally produced by rendering, a process which raises a red flag to cat enthusiasts. I would definitely recommend avoiding cat foods containing these ingredients.