I will never believe in any commercial pet food again, once I learn about the legal aspect of this:
From the article:
"Most of grocery store dog food formulas, contain "meat and bone meal" which has been known to contain dead dogs and cats that were euthanized in animal shelters. Their bodies are picked up and bought by the truck load by "rendering plants" , that also pick up road kill, dead live stock, and etc. They are shredded, and boiled. They skim off the fat on the top of the "soup" and collected it and sell it to pet food companies as "animal fat", the rest of the animals' remains are crushed up, dried and sold to dog and cat food companies as meat and bone meal" : http://earthislandprojects.org/eijournal/fall97/fe_fall97petfood.html
From the article:
"Because of persistent rumors that rendered by-products contain dead dogs and cats, the FDA conducted a study looking for pentobarbital, the most common euthanasia drug, in pet foods. They found it. Ingredients that were most commonly associated with the presence of pentobarbital were meat-and-bone-meal and animal fat. However, they also used very sensitive tests to look for canine and feline DNA, which were not found. Industry insiders admit that rendered pets and roadkill were used in pet food some years ago. Although there are still no laws or regulations against it, the practice is uncommon today, and pet food companies universally deny that their products contain any such materials. However, so-called “4D” animals (dead, dying, diseased, disabled) were only recently banned for human consumption and are still legitimate ingredients for pet food" : http://www.bornfreeusa.org/facts.php?more=1&p=359
Now I myself cook food for my dogs and cats.