labs who bolt or escape

Question
My daughter has a black lab who will do anything to escape her large back yard....dig..knock the board or chew the fence.  They have wired the fence and that works for a while and then she finds a way.  She will bolt and not come home until someone finds her and takes her to her vet or they finally find her.  Help...they have tried everything.

Answer
Hi,
Is the dog spayed?  It seems she is not bonded with them too much.  Have they tried and invisible fence?  
Ok,  for starters.  Get a backpack at the pet store (Petsmart has them)  put a couple of water bottles in it.  First thing in the morning.  Take her for a 30 to 40 minute walk.  The added weight will tire her out a little.  This dog (and all labs) have an abundance of energy.  While on the walk, make sure she is not allowed to move from her owners side.  Keep the leash and collar high on the neck.  A greyhound collar is a good collar to use.  she is not allowed to sniff anything and must walk right in the heel position.  Not being able to sniff and being controlled tires a dog out faster.  She has to work at controlling herself.  The attitude of the handler is important here, she must be very much in control and be thinking (YOU WILL BEHAVE)
The above and an invisible fence should help.  When they get home from the walk she should be walked around the perimeter and told to "stay in the yard"  This is not an overnight cure and must be worked on continually.  The biggest problem with these types of dogs is that people give up instead of making it a life-long commitment.
Nancy