After I read Honey's post about knuckle bones being good for cleaning dogs' teeth, a mystery was solved. I'd heard about knuckle bones but didn't know what they were. But Hsin-Yi, Honey's human, explained that they are the knobbly ends of marrow bones, with the hard, potentially tooth-breaking middle cut out.
Since Penny did break a tooth when she was young, and unfortunately had to have it removed, I'm nervous of bones. But we give them to Penny because we realise the value of bones as part of a dog's diet. Usually we stick to the soft brisket bones of beef or chicken bones such as necks, but I decided to take Hsin-Yi's recommendation and try Penny out on a knuckle bone.
She worked on it for about thirty-five minutes, actually getting quite puffed with all the exercise, and then buried it in the backyard for later retrieval. I was pleased at the way she took weight on her back leg during the long eating session, and also at the way she walked down the steps to the garden. Her limp was more apparent on the way up the stairs after she'd buried the bone, but we do realise she may limp for as much as six months after her surgery on the cruciate ligament.
Here's a video with the story of the Magnificent Huge Bone.