Is there a way to prevent my dogs from digging under the wood fence I

Get some chicken wire or livestock fencing and dig a trench inside of your fence. Bury the bottom of the wire under the ground and tie the top in with your existing fence. Cover the tamp down the ground where the trench is. This worked to keep my dogs and wolf inside.

Dogs do not like moth balls, you might try putting a good number of moth balls all along the fence. You could also amend the fence and put wire under it even down into the ground a foot or more. Once dogs learn they can get out or find a new game to play, they will continue. Our dogs were digging for fun as puppies and we taught them "no digging" right away. We always stayed out with them to prevent such activity. It is in the training in prevention, but since your dog has already found it a fun challenge, you need to make it unpleasant. If it were my dog I would do both the wire (cattle wire or stronger, dogs can easily break chicken wire) and also the moth balls for a season or two until it learns the fence digging will not work any more.

this idea works great. I had to bury my about 8-10 inches. Darn digging dog. 😂

Heres a few great ideas that are budget friendly too💰 The rocks of you live near a river and use a bigger one than the decorative ones to prevent him digging and the weed trim prevents digging and of course a board flush to the ground and nailed to each post🔨⚒

Mothballs are likely effective but they are also toxic and then you have the odor. Fencing will work but is labor intensive and can be costly also a nuisance for future projects in the perimeter. My solution is to use an electric fence charger with a single strand of wire/tape around fence bottom with insulators attached to fence. This is both humane and safe for all. Dogs will soon learn not to even explore the fence bottom.

Bob Parsons, years ago the electric fence charger that is available at farm supply stores was the answer to my same problem with the dog digging out under our fence. One time touching the charged wire was all it took, from then on all I had to have was the wire, I never turned the charger on again but that dog would not go anywhere near the fence after that.