Chelsea is 12 and has never been a hard chewer--nowadays pigs' ears are about as "tough" as she'll go. Humphrey is 7, bigger, and a power chewer, so I bought him an antler. He loves it. Twice this week I have heard "chomp, chomp" and walking through the living room there is CHELSEA gleefully gnawing away while Humphrey lies there looking sad. She will dance around the room waving it in his face and daring him to grab it; if he tries she snarls ferociously and makes him back off.
If he leaves the room she drops the antler and goes outside to chase birds.