Trying to pick a new canned food for Jake

Question
Our 13 yr old German Shepherd is quite a picky eater.  He is under vet care for what we hope is a minor gallbladder issue, and we are trying to decide on a canned food for him.  We are trying Natures Variety right now and he seems to like the chicken stew, it's chunky and that makes it easy for me to feed him because he demands his food be handed to him!(not spoiled at all!! lol) My question to you is what's your expert opinion of this dog food?  It's the Homestyle and it seems to have some wonderful things in it I think, but I'm not the expert.  Give me your opinion please.

Answer
The truth is, I have very little data to base an opinion on.  Unfortunately most of the people on the internet feel their reasoning is more valid than any study would be.  Hardly any of the real information about canine nutrition is available for free on the internet.  Let me assure you what you will read elsewhere isn't based on studies published in the JAVMA or the Journal of Nutrition.

My opinion is that food likely has about the same nutrients as most other foods, and if it is working for your and he does well on it, you should stick to it.  While no one diet is right for all dogs, most dogs will thrive on most dog foods.  I am including support for my reasoning below.  You may or may not choose to wade through it.  

You can go to sites like www.dogfoodanalysis.com and check what ingredients are in it and see their rating.  However, their ratings are strictly based on speculation about the ingredients.  There is no input of how dogs eating a food fare, or even a comparison of what nutrients that are available in it to the well know canine nutritional requirements.  A list of ingredients tells you very little.  It doesn't tell how much is there or how it has been processed.  Processing is very important.  It makes some nutrients available, but destroys others.  

I find most discussions of dog food filled with hype, half truths, lies, emotional button pushing, and a strong anti business attitude.  One of the few sites presenting a balanced view is http://www.woodhavenlabs.com/articles2.html#nutrition  As I said, balanced, good common sense and links to what I consider kooks.  There is another side to the debate, http://www.fda.gov/ForConsumers/Cons.../ucm208365.htm
 http://skeptvet.com/Blog/2009/07/pet-food-nutrition-myths/
http://www.nytimes.com/2010/06/01/health/01brod.html
 http://www.dogsincanada.com/pet-food-facts-and-fallacies

It is like Aristotle and Galileo. Aristotle though about it, and declared heavier objects fall faster then light ones. For most of the next 2000 years, educated people knew that. Then at the dawn of modern science, Galileo lugged the large and small balls up the the tower of Pisa, and dropped them off. They hadn't read Aristotle, and both hit the ground at the same time. I am afraid the dog world is full of thinkers. Most of my answers are based on my own results trying what I have been taught by the best there is.

Before the current form of the net existed, we were raising puppies for a large dog guide school that feeds Pro Plan, no better rated than Science, Iams, etc.  Once I started reading how awful it was, I started digging.  What I have learned is that many other service dog schools with all their resources to determine the best diet and the incentive to do so, are feeding back of the pack chows including Iams, Science Diet, and Pro Plan.  I have not been able to find any research backing up the claims of the premium chows.  I have challenged people on open forums to provide me with research backing the premium chows.  They don't seem to appreciate the importance of controlled testing.  Those selling premium chows are very good at exploiting the emotions of many.