Dog hasn't eaten in 4 days!

Thanks for the replies everyone. Like everyone else I was thinking it could be one of a million medical conditions. Today I came home on lunch to ck on her and she still had not eaten. At the suggestion of my wife who said "maybe she is just sick of her food", I gave her a scoop of the cheap ol roy food my wife feeds her little yappy house dog, and she scarfed it all up right there like she hasn't eaten, well, in like 4 days. What the heck, she wouldn't even eat hot dogs last night. So this evening when I went to feed, I gave her the sports mix she has always eaten, she went over and sniffed it then walked away. So I went back and got some of the ol roy for her and she ate it all as soon as I put it down! Really? She's gonna turn into a picky eater all of the sudden?

Anyone ever had a dog just quit eating one type of food like that? When I used to feed diamond I got a bag that smelled "off" one time, and the dogs wouldn't hardly touch it. Haven't had that issue since I switched to sports mix. And it was the bottom of the bag that I've been giving her the last few days as I just had to get a new bag today so she's already eaten plenty of it. I'm happy that she's eating again but it kind of irks me that she done that. I guess I'll just keep feeding her the ol Roy for a while and see if she'll go back to the sportsmix.