You can pruchase Pro Plan at Pet Smart or Petco (and likely at other pet stores). I have seen the regular Purina in the grocery stores, but not the Pro Plan. If that doesn't work for Gizmo you can try going with the grain free cat food. One of my guys can NOT tolerate the dye and corn in commerical cat food (I get projectile vomiting from the highest place in the house if he eats it ). But there are plenty of options out there for you, so don't worry