It's possible that your dog's stomach just reacted differently than most dogs might to a new food. Some dogs have ultra sensitive stomachs, and if you'd been feeding her the Canidae for a long time, even with a gradual switch, she probably had a reaction from that. Don't advise people to 'never, never' buy a food based on only your dog's reaction when there are several dogs who have nothing but positive outcomes.

I've been feeding my dogs Nutro Ultra puppy food for only a few days now. (they're not puppies any longer, but they have been VERY picky about their previous food that they lost a lot of weight, so the puppy food is to help them pick up some of that again- and huzzah, all three dogs LOVE the food!). None of them have had such a violent reaction to date, and we actually did switch the food quite suddenly. They were initially eating Diamond Natural, which isn't terribly easy to come by, then were switched to Purina Pro Plan but they weren't taking to that, either. A Nutro representative gave me a few coupons and suggested the Ultra that her own picky eaters absolutely loved...it's the first time I've seen our dogs actually excited about eating their OWN food.

My dogs were origionally on Canadae, the foods are very similar, only thing with Canadae is it is all life stages, which I can't imagine giving a puppy and a senior dog the same thing because the have different nutritional needs, but whatever works for you.