Are you sure there's a regulation regarding listed ingredient order for pet food? And regardless, I bet manufacturers can get away with even more ingredient list manipulation there than with human food—I might be wrong though.

Checked my friend's dog's food: lists cereals first, “meat and byproducts” go second in a single item.

It depends on the type and quality. If you purchase a can, then I would hope that it is mostly animal based ingredients. If it is dry food then it will be mostly cereals.