I have no problem with switching my dogs' foods now and then. My dogs have great stomachs and have yet to get an upset tummy from switching foods. I think the raw diet helped with that a bit. I've switched kibbles at least 5 times (cold turkey) with no nasty reactions. We finally found a kibble the boys and I liked so we've stuck to it but..by all means, don't feel bad if you need to switch now and then. Just make sure it's a good food, that's all. If Layla has a sensitive tummy, you could do the gradual switch but I don't think it'd be too big a deal if you switch now and then.