Vicki, good news for Dudley and his wounds..and ears too.
Sounds like your plan is great and that he will get the care he needs..very "proud" of you, as a fellow human and caring person I commend you for your hard and diligent work..Dudley does too..I know he does.
As far as the food choice goes for Dudley's owner, why don't you tell her that you started, out of curiosity, to do some research on different dogfoods and ask her to join you in the quest?
I have a link to another forum (chicken related, so I hope I am not stepping on anybody's toes), this one has a "grade the dogfood you are feeding type chart", so you can do it on your own, instead of feeling as if you are told what to feed by the various company's or the like. There are several foods on here that are the cheaper versions as supposed to only highdollar foods, so she doesn't have to feel as if she has to fork out tons of money, it might help her open her eyes.. Good luck, I hope it works..
http://www.backyardchickens.com/forum/viewtopic.php?id=67485