Haven't read all the responses, but tons of good info here.
I think Chicken Soup is really good for the price, but chicken-based foods give Mud gas.
Lol. Also it was too low cal/low-fat for my dogs and I was having to feed way way way more than recommended. But I definitely don't think that is
all dogs, so don't let that scare you away from it. It is certainly worth a shot.
If it is an allergy causing her dandruff, it could be something
other than what she's eating--something environmental. Shampoos, household cleaners, type of grass/trees/flowers she is around regularly, so so many environmental things that could be the culprit, too. So if changing foods doesn't solve the issue, look for things in her environment.
I typically have a food that I feed regularly and split it with various other foods. I've been feeding Taste of the Wild for a while now, and once I got them switched to it I rotated between the TotW formulas, then started mixing other foods in too. I like the venison formula the best, but I do rotate still. With so many foods being in their diet regularly, they can just about eat anything without any tummy upset. When I first started this I would be careful to introduce the other food slowly, but now I just mix it all half-and-half and they are fine with it. Sometimes the extra food is Blue Wilderness, sometimes it's one of the Merrick foods, sometimes it's Innova....anything that is still a good food but isn't super expensive. They haven't had Blue Wilderness in a long time because I haven't been able to swing it, but I used to mix it pretty regularly.
As for high protein, from all the research I've looked at it seems that the
type of protein is the key. If it is high protein, but all of the protein sources are easily digestible, then it's alright. If it's high protein and the protein sources suck, then it's not alright. All of the foods mentioned so far have all been foods that are safe as far as protein goes. My dogs have been on higher-protein diets for a long time now with no issues.
I also add in canned food and raw sort of at random, they usually get each at least once a week. I think with all this variety they really have tough digestive systems. Also since this Zeke has actually been super excited about mealtime--he used to not even care about mealtime. He never knows what he will get so he's excited to see what's coming.
As for canned/raw ruining a dog's appetite for kibble, it's mostly just a matter of how much you put up with. For instance, my mom's teacup Chihuahua ate crappy food for years. I kept trying to get him on a better food--he would eat it just fine for a couple weeks, then stop. Mom had it in her head that he would starve himself if she didn't put him back on his crappy food.
Several food change attempts ended this way. He knew if he stopped eating what we were giving him, he could get something different. Finally around the middle of last year I somehow convinced Mom to just let me feed him what I wanted and stop catering to him. He's been on a good food ever since and eats it just fine. He knows now that he has to eat whatever is given to him, not whatever he
wants.
Another example is coincidentally another Chihuahua I met several years ago...he had been on a diet of HOT DOGS(not kidding) for the majority of his life. His owners claimed that if he was given kibble he wouldn't eat. Dogs won't starve themselves, but they will test their limits to see if they can get something different. If we give them something different every time they don't eat, they know they don't have to eat what they're given---something else will come along. With some convincing, the Chi's family decided to try yet another good dog food. He had 10-15 minutes to empty his bowl. If he didn't start eating within the first few minutes, the bowl was put away. If you want to get to eat, then do it. If he had only picked at it in the 10-15 minutes, the bowl was put away. No more food until next meal time. He wasn't going to get something else just because he didn't eat what was given to him. In 1-2 weeks he was cleaning his entire bowl of kibble. The next time I saw them was about a year later, and he had lost several pounds(down to a HEALTHY weight!) and was off hot dogs.
Still eating good food. Yay! His vet was very happy with the change.
Also how long do you normally take to switch foods for Shivon? I used to have a Weim/GSP with a really sensitive tummy, and we would take at least 2 weeks to transition him to a new food so it was extra-easy on his stomach. He went through probably 3 food changes with me and also had a mixed diet like I feed now, so by the time he was rehomed his stomach was much less sensitive and he didn't really need the 2 week transitionary period anymore.