Best food for a maltese puppy?

UGH! Purina products are some of the worse dog foods on the market. Since you are in Ireland, I can't recommend any dog foods since I'm in the United States. Go to a local feed store, or high end pet store and start reading labels. The first 3 ingredients should be meat products, not by-products or grains. There is no need to feed puppy food, it just makes them fat. Feed the pup a high quality dog food. I like Canidae For All Life Stages, not sure if it's available in Ireland, but you can go to the Canidae website and see the ingredients the dog food is made from.