Just go to the meat department where you grocery shop and find the soup bones. They are totally unprocessed so less chance of some kind of allergic reaction. Way less expensive too. My dogs love them and sometimes I ask the butcher to cut some about 4 to 6 inches long rather than the smaller ones they generally have. You can freeze them too.
Just to tag on a bit.... I love the idea of treats in the bones. I know Norm would love some peanut butter. Can he have that much at a time? I know he'd sit and lick until it was gone.