Yorkies can be VERY picky eaters. My dog has very refined tastes. Even my food is not good enough for him sometimes!
I think Iams has a lot of grease on the food to make it tastier -- dogs are like humans - it will take him a while to get used to a more nutritious food. I also recommend you try another food altogether. We're having some success with Spot's Stew. If you keep him on nutritious, relatively lower flavor foods, then his palate will change and those will taste better. That being said, there are limits! Thor loves Breathies also, dehydrated lamb lumg treats, Solid Gold small jerky treats, and yorkie yummies. He'd rather die than eat a Zuke's treat. Keep trying, you'll find stuff he loves.
