[yorkieusa]

Have you had her since she was a puppy?

Have you been taking her for walks since she was a puppy?

If the answer to both questions is yes, then I wonder if the grass is too tall where you are taking her. Other than that, I can't think of any reason for it. Usually, when you've taken them since they were puppies, then they are used to it and will relieve themselves on a walk.