If shes gone off her feet before and you've had to give her mars bars,she has been over run. I learned the hard way and lost my best bitch chasing the numbers. She was a game bitch who would run till she dropped-literally. She had a couple of "wobblers" which meant carrying her back to the car. The third time she was not so lucky-she died on the way home.
My advice is quit while you're ahead,or more to the point,while she is ahead,especially if she hasnt lamped for a month. Believe me,if you kill the bitch you will feel a complete c**t-i did and still do.