My Dog is Allergic but hungry...

Hi Matt, great questions and answers here. I've read a lot of your posts and finally have a question to ask you myself. My labrador is about 9 months old and had some bad infections in his ears. He is now on a food trial so we can determine if it is some sort of food allergy. He is only allowed to eat Hill's Science Diet z/d Ultra Allergen free food and nothing else. He likes the food just fine (my wallet hates it) but he is a young lab and loves to chew. I can't seem to find anything that he likes that is allegen free that he can chew on. I take him to work with me and I am growing tired of chasing him around the office and taking all the stuff he finds from his mouth. Do you guys have any good allergen free dog bones or dog chews?