People often give their dogs bones as they assume they can not be harmful as they are full of nutrients and completely natural. As you are well aware, even though both these statements have some truth in them, in my opinion it is never a good idea to feed your dog a bone. The main reason for this is that the dog naturally crack the bones open to get at the bone marrow. If not chewed sufficiently broken fragments of bone can be swallowed, and as stomach acid is very slow at dissolving bone these fragments can cause blockage/perforation of the gut, which if left untreated will be fatal.  Different types of bones have different amounts of risks associated with them. Chicken bones for example are in my opinion a definite no, they fracture into sharp spears of bone when broken, which are inevitably going to puncture the animals digestive system at some stage. It is also quite common for broken fragments of bone to lodge between the back molars in the dogs mouth while he is crunching the bone.