For further learning:

iDog Nutrition forums

Wysong Optimal Health Program

How to Apologize to Your Pet

Gluten intolerance and your pet

The Dog Food Project

Dog Food Reviews

Food intolerance in pets (gluten, etc)

Contrasting grain-based and meat-based diets fed to dogs

What's really in pet food (references at bottom)

The Dog Food Project- ingredients to avoid

The Dog Food Project: Identifying better products