There have been times when one of my two yorkies does not eat. At first I thought it was a bit weird, and was worried that maybe he wasn't feeling well. But after some time of him doing this and switching his food multiple times, I have figured out that my little one is simply just a picky eater! This may be because occasionally we spoil them with a little fresh chicken in their food.
If a dog is hungry though, he will eventually eat no matter what. Only in extreme cases will a dog ever not eat because they are too picky. I have been feeding mine Blue Buffalo and so far my picky eater loves it! They both love a little warm water in it to make it nice and mushy! mmmmmmm