Pet food

Question

I found this on a website: "This means that cat and dog food may contain pork meat, and it may contain cow meat from a Christian, Muslim, or atheist (or whatever) butcher. You may not eat it, but your pet is permitted to eat it. But if it contains both meat and milk, you may not feed it to your cat or dog, because you are then deriving benefit from that food." Is this true?! I don't have a pet and thus don't have to worry, but this concept seems very strange to me. Thanks for your terrific site!