its called detox, he is eating kibble and then you give him a raw bone. that is a problem with some dogs its fine but for many its a no-no. why? because kibble digests really really slow, while raw digests in about 1 minute, and this will make him sick. what you may want to do is give him a bone in the morning and give him kibble at night, or give him kibble in the morning and dont let him anywhere near kibble for the next 10 hours or so THEN let him have a bone. he may still have detox for the first while, and it may last a long time if you dont give the bone every day.