Switching dog food suddenly?

I would return it and buy the right food. It's been my experience that Blue wilderness isn't great for dogs with sensitive stomachs to start with. When i tried it several years ago, both of my dogs experienced diarrhea, vomiting, and gas even with a gradual switch, and my experience isn't unique. Switching abruptly can only make things worse.

Take it right back and exchange it. Now. You know your dog will have problems if you don't.

You can by a small bag of Solid Gold and start slowly mixing in the Blue Wilderness and feed her that. Honestly, I dont recommend gradually switching, so maybe the best thing to do is return it and buy Solid Gold.

I would buy a bag of Solid Gold to switch gradually, otherwise she probably will get sick.

i would suggest buying a bag of Solid Gold immediately and adding in a portion of Blue Wilderness gradually as you said she has a sensitive stomach and switching food out of the blue may cause her digestive system to go into shock which may lead to extreme food poisoning if she can't agree to the abrupt change. Don't waste your bag of Blue Wilderness. just add it in small portions so as to finish the bag off. Hope this helps! :)

shell get diareah

You need to get a bag of the old stuff and mix it. You don't want her to be sick.

It may upset her stomach for a few days, but it's not going to harm her in the long run. Just be prepared to deal with diarrhea and gas for a week or so.