I guess I'm hard-hearted. My shih tzu would get that way and I would just .. let him have his little hunger strike. Eventually, he would break down and eat and then the pickiness would be over. I would say 2 or 3 days. Offer the food, if he doesn't eat in 15 minutes, take it up and put it away. My pup has shown a little disinterest in his food in the past few days. One thing that helped was crating him and giving it to him. Less distractions meant he focused more on the food.
Xan Varik von Fernheim (born 4/3/13)