What's in your pet's food? You don't even want to know.
But I'll tell you anyway because I'm a sociopath.
Dog food and cat food sold in supermarkets contains what's called "rendered" animal material. The pet food companies themselves don't know exactly what animals are in their pet food; they simply buy a "product" from rendering factories and put it in the pet food. Rendering plants get any dead animal or animal flesh leftovers and grind it all together into an undifferentiated mass.
According to the Wikipedia, rendered flesh is made up of slaughterhouse scraps too nasty even for hot dogs, and also "restaurant grease and butcher shop trimmings, expired meat from grocery stores, and the carcasses of euthanized and dead animals from animal shelters, zoos and veterinarians."
That's right: Your pet eats other people's dead pets every time they eat.
According to Slate, rendering plants also accept road kill and animals that have died of diseases. Some dead animals have been heavily treated with veterinary drugs, some of which make it through to the pet food, so your pet is also being randomly drugged.
When rendering plants add meat from the supermarket that has gone bad, they dump it in complete with plastic and styrofoam, so pet food contains those "ingredients" as well.
But don't worry. The pictures and language they put on the label showing and implying whole-meat foods and wholesome ingredients makes it all OKhttp://en.wikipedia.org/wiki/Rendering_(animals)http://www.slate.com/articles/health_and_science/science/2013/04/what_is_in_pet_food_zoo_animals_sick_livestock_dogs_and_cats_from_shelters.single.html