Exercising the Jaw muscles

Gave Spike his first bone yesterday, at first he wasn't sure what to do, then quickly discovered he could eat it!! The marrow soon went, to much crunching and licking, now only the bone remains, and he still works away at it, making strong teeth and bones...... His second toy. It is amazing the power in his jaws, even though he is only a small dog, wouldn't want to be bitten by him !!!