hi there,
not sure if she is biting through rope? but you can buy some great little 'locking' carabiners ( like rock-climbing ones) you need to spin shut the barrel so a dog finds it hard ( not impossible
) to undo.
A more extreme method is what the Alaskans do and that is they run a length of hose pipe over the rope or chain, so then it is impossible for the dog to get to her own moorings...hope this makes sense
Annie