Reasons not to feed corn or soy to your dog

Corn & Soy are made up of short-chain fatty acids, that are known to inactivate lipase, hydrochloric acid & pepsin (Brosey et al. 2000), this inevitably has a negative effect on digestion, especially of proteins and therefore the amino acids necessary for mood regulation.

Here's another scientific article about how feeding a high protein, no-grain diet, has a positive effect on behaviour: http://www.animalmedcenter.com/news-and-press/article/the-influence-of-nutrition-on-aggression