Here is a site that will show you which dog foods are the best and the worst. I suggest that you get any one of the dog foods that are top rated.
Most of grocery store dog food formulas, like IAMS, Pedigree, Science Diet, Purina,and etc 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.
You can read more about it here.
Here is an article where the owner of a rendering plant talks about it. He says that cremating the dead shelter animals would cause pollution, and that rendering them is good.
Here is further information on what you shouldn't see in the ingredients list in your dog's food.
Top rated dog foods like Canidae contain good healthy ingredients.