Is Effie raw fed? If she is, then its unlikely to cause any problems even when its a few days old, in fact as far as the dog is concerned the honkier it is, the better!! If she's not generally raw fed then it it might be better not to leave it too long, although I'd let your nose be a guide, if its really inedible, you'll know it!
Just a tip to keep an eye on her poohs - too much bone can make them a bit hard so if she's not had them before, its a good idea not to let her have too many at once!
Hope she enjoys it!!