Trying to keep a dog from digging a hole to get out of your fenced in area is a lot more difficult than you would think. Dogs are very sneaky animals. They are rarely afraid of anything and will chase anything that moves. They are very curious animals and it is only natural for them to test the boundaries and try to escape from your fenced in yard.
However, you should know, there is nothing you can put around a dog fence that will keep them from digging. I mean, I am sure there are some things that you could spray that smell really bad, but you don't want to put anything where your dog is if you don't know if it's dangerous to them or not.
Now, that does not mean that you won't be able to stop them from digging. They do have dog fences that are designed to keep dogs from digging their way out. You can find these types of dog fences online at places like, /www.doggybakery.org/want-best-dog-fence-money-can-buy/ .
Choosing to purchase a new dog fence will be well worth the investment and you will feel better knowing that your dog is safe inside your yard and not out in the road where it's dangerous.