Only if cooked first, as they become brittle. So cooked chicken bones would be especially risky. Raw bones are generally fine - they break into small pieces. Larger marrow bones they can only gnaw at of course.
The sound of a couple of German Shepherds crunching up their bones means you probably don't want them doing this right by the sofa during a movie. After an hour or so all that's left of a big marrow bone is entirely cleaned, and the smaller stuff is gone completely. So we've never found it an issue.
I imagine we and the children, especially when they were younger, spread as much as any salmonella loaded paw prints. :)
Generally though, unless contaminated at the slaughter house, bones should be generally free of bacteria since it's just muscle, fat, ligaments and bone. All of which should be sterile at time of death.