Just this week I started Sophia and Kimo on Natural Balance Duck and Potato. I have been incorporating it slowly and hadn't even gotten to using 1/4 old food and 3/4 new food before Sophia started having loose stools. I just found a site with a lot of complaints about the Duck and Potato formula. I'll be heading to the pet store tomorrow morning and switching them back to Nature's Variety.
Dick Van Patten's Natural Balance - Reviews on RateItAll