RMBs cause diarrhea?

I'm not a raw feeder, but I don't believe you're supposed to feed weight-bearing bones like drumsticks.  Wings, necks and backs are better choices.  I think the bones in non-weight-bearing parts are supposed to be easier to chew and more digestible.  I'm not sure if that would have anything to do with diarrhea, though.

If the drumstick has skin on, it might be the underlaying fat and the marrow that she is not used to that caused the loose stool. You might want to try a chicken neck for RMB next time, half a turkey wing (skinned) or at least skin the drumstick. The meat/bone ratio in the drumstick is pretty high in favor of meat so if your purpose is teeth cleaning (and fun), a part where there is more bone and less meat would probably work better.

The weight bearing bones that people are often advised to stay away from are cow, deer, bison, etc long bones. Those are very hard and can lead to tooth breaks if the dog is a very heavy chewer and is allowed to go to town on the bone after all the remaining attached meat and tendons are gone. Chicken bones are pretty soft by comparison.

Thalie

If the drumstick has skin on, it might be the underlaying fat and the marrow that she is not used to that caused the loose stool.

  I agree; the marrow is very fatty and often causes the runs. Jessie can't have raw bones anymore because of pancreatitis, but when she could have them, I didn't like giving her turkey wings because the bone splintered a lot. I don't know Piper's age, but chicken backs and turkey necks are very high in phosphorus, which is important to know when giving bones to an older dog, especially if they have kidney problems.