We've had raw bones go sharp too. Maybe talk to your butcher about what you can give him. Our butcher sells lamb shanks as dog bones - but the problem with those are when they chew them down, on two occassions our beagle has ended up with the chewed bone wedged over her back teeth, leaving her distressed. As our dogs are smaller than your lab, we stick now to raw chicken necks when we give them a bone.