Thixton's book is less than $15 on Amazon... make it a Christmas gift to yourself (or better yet, your kitties). 
While you're waiting for your book to arrive, you can watch a documentary called “Pet Food: A Dog’s Breakfast” that aired in Canada, available through several venues, including the blog "Poisoned Pets" (scroll down to the bottom of the page).
And here's something available online by Ann Martin: Why Is the Pet Food Industry Killing Our Pets?, an article by Born Free USA: What’s Really in Pet Food, and another article by Purely Pets: What's in your Pet's Food?.
I almost forget - Thixton has a website, TruthAboutPetFood.com that I highly recommend you regularly check for recalls and other detailed pet food-related info.
If you google "What's in my pet's food?", you'll get pages and pages of information, but I would really recommend one of the books, as they are more thorough and go into details such as the connections between AAFCO, the FDA and the pet food industry - stuff you might find very interesting.
Best regards!
AC








