The dog food companies that are adding these disgusting things to their food don't advertise it but if you look at the list of ingredients and research you can figure out what it is.
You have to look for the companies that are happy to tell you
exactly what they are putting in their food and what they are not. There are companies that sell food with only ingredients that we would eat, unless these companies are out right lying but I have to believe there are animal lovers out there who want to make a quality food available for our pets. They just have to charge more and I'm willing to pay.
Here is an article about one of the foods I use.
www.flintdogfood.com/whyfrr.htm