do a search on here and you should get lots of info. Also, here are some links:
http://en.wikipedia.org/wiki/Ethoxyquin http://www.avianweb.com/ethoxyquin.htm http://www.cbc.ca/consumers/market/mp30/ethoxyquin.html http://www.executec.com/nutra.htm
It's basically an artifical preservative that has been linked to many illnesses in dogs...It's particularly not good for a dog who has liver or kidney issues as those are organs that are necessary for "filtering" and this type of chemical stresses the liver and/or kidneys too much.