If your dog has been sick (i.e. Giardia) she
needs a bland diet (chicken and rice) to help her insides "heal". Once her tummy is stronger you can switch her back to her regular diet...
slowly.
It is not a matter of simply "switching foods". Your dog is having diarrhea b/c her tummy cannot handle the richness of most dog foods. This is because of her illness (Giardia). Trust me...I just went through this...actually, I still am
.