Evo also carries cat food. It'd be ideal to mix it with their old food for a couple weeks, starting with mostly old food and a little Evo, and ending with mostly Evo and a little old food. I switched my two dogs not long ago. The only thing I noticed was one of the dogs got.. rather gassy . But that seems to have died off now. I'm guessing it was just an adjustment to a richer diet. Overall I've been very pleased.