My dog is a 15 year old pomeranian and has an extremely delicate system.  He has skin issues and is on a very clean, chemical and by-product free diet.  I make real chicken for him and watch any kind of food he gets to avoid his allergy breakouts.  It has always been hard to find him a treat or snack that doesn't freak him out (too concentrated) or that doesn't upset his digestion and skin allergies.