Digging under the fence

Question
Hi
I have a 3 1/2yr old German Shepherd (female) who is an absolute joy.  Three weeks ago, she dug a very large hole under a boundary fence (this was the first time she had ever done this).  This was filled in and no further digging until 2 days ago when another much larger hole appeared under the same fence, less than a metre away from the first.  I think I have found out what has her interest - neighbours have acquired a young goat and it is tethered in their back yard (in lieu of a lawnmower methinks).  My concern is that she is going to successfully get under the fence and 'play' with the kid.  How do I discourage her from doing this please?  Both holes have appeared while I have been away at work.
Sue

Answer
I have my fence lined with flagstones.  Some people run the wire down into the ground.  Paving blocks or poured concrete will work.  You could put up an electric fence or a wireless inside the other fence.  You could find a doggy day care for her.  I don't think there is any training a dog not to dig.