
Hi Sarah,
What was he eating with his breeder and were you not recommended to stick with that? Swapping diets not only risks upset tummies but constant switching around will encourage faddy eating habits in even a non-fussy dog :( Pick a quality diet (again, I'd check with breeder if you were happy about the health and appearance of his / her other dogs and the litter of course) and stick with it. Put the food down, give your puppy say 10-15 minutes (I make that shorter for adults) to eat his dinner and then lift anything he leaves. Repeatedly do that at correct mealtimes - offer no treats, snacks in between. Don't leave a bowl of food down for him to use as a self-serve buffet either - or that's exactly how he'll treat it. Presumably you're feeding 4 x daily so after two days or so you will have been very strict with him at least eight times - that's a pretty good start :)
HTH for now,
Good luck, be patient but above all be consistent!
Teri :)