Is your puppy gaining weight? Or is he on puppy food? Remember that these little guys have very tiny tummies. they can only eat so much at once, then well, poop the rest out.
Is he playful, and happy? He does not have any worms or anything does he? I would first make sure nothing else is going on with his health. AND if all of that checks out fine, then start looking other foods.
My 4month old girl eats a food called By Nature. It is suppose to be very nutritious . I also tried the Life's Abundance, and Suzi was ot keen on it either.
whatever you decide to do, start out slowly when changing his food.
