I understand some poor folks actually eat road kill like deer, squirral, and rabbit. I find the whole thing just disgusting. But a dog will eat another dog's vomit and so will most cats, they see things differently.
Cats will eat an entire mouse or rabbit bones, skin, eyes and all.
Some dogs will too.
Dogs will eat rotten carcass.
I am not saying what they put in animal food is the right thing I am just saying that is how animals are.