I had to try 4 different brands (kibble and dry) before I found a brand Alice likes - Nature's Variety, they have lots of different flavors too so you can change it with each bag and keep them interested. I tried mixing all kinds of things in with the other kibbles, didn't work, heating it up didn't work, 2 of them she ate for a few days then stopped, so that's why I got the idea for the NV with all the different flavors.
Sometimes too, you have to wait until they're really hungry -if she's being picky now (which is very rare), I don't give in, I take it away and when it's time for the next meal a few hours later, she's always very hungry and gobbles it up. Once you find a food they like, that's all you have to do and they get the picture
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Just an fyi - Iams isn't better than Science Diet. Still full of corn and by-products, it's about the same thing, maybe even a bit worse.