 I use Evo small bites for three of mine
The fourth is on a prescription diet because she has a porto-systemic shunt, and the Evo is too high in protein for her.
All three of mine have done very well on Evo, but there are a lot of good foods out there. I would not recommend ever feeding something you can buy at a supermarket or a Walmart/Target/etc. Mass-market foods are less expensive because they contain substandard ingredients. It tends to even out because dogs don't eat as much of the food when it contains higher-quality ingredients. A 29 pound bag of Evo costs me $40 and lasts for about four months. Nobody goes broke feeding a Yorkie no matter what food they use.
Whatever you switch them to, it will require patience. Samples are of little help because you need to gradually mix new food with the current food, even if it's not a good food. You're not going to see the full result for about two weeks--one week to gradually switch them to the new food, then another to have them strictly on that food.
All that being said, I would strongly suggest that you have a vet look at her, and take a stool sample with you. Chronic diarrhea is something to be concerned about regardless what food you're using. Even cheap foods wouldn't typically cause that unless they have an ingredient she's sensitive to. (That's not beyond the realm of possibility.)
Best wishes,
Jade |