Hi guys..my little Willow came with Pro Plan Puppy for small dogs. I have a bag of Eukanuba Puppy for small breed and have mixed a bit in thinking I would switch to Eukanuba. Then I heard someone say ProPlan is good....then some say don't feed Cavaliers puppy food. I used to feed my Lhasas Nutro brand because it doesn't have preservatives. What do you all think about foods? Should I be transitioning him out of puppy food?