I'm sorry to hear that you're having these difficulties with your boy.
I think anxiety is what's causing this. Boredom can cause similar problems, but this is pretty extreme for boredom. But we'll try a few things just in case that's a factor.
Due to the extreme nature of his behavior, I would consult your vet. I think that this is a case where medication could be very helpful. There are anxiety medications that are made specifically for dogs and in my experience, they can work extremely well. Clomicalm is one particular drug that I have experience with and we've seen great results in numerous animals. I've worked at an animal shelter and I've taken in many foster dogs, often with anxiety disorders, so I've had the opportunity to see this drug used in many different animals, and all had a significant degree of improvement, with minimal side effects.
In terms of a non-RX remedy, I think the next-best thing would be a holistic, natural remedy. Some people swear by holistics and find these remedies very successful. I have a moderate degree of experience with these sorts of remedies, and I've found them to be helpful, although not as effective as Clomicalm.
Here's two products that I have tried and liked: http://www.holisticpetinfo.com/proddetail.asp?prod=Sedaplus http://www.holisticpetinfo.com/proddetail.asp?prod=Quiet%5FMoments%5F30%5Ftablets
There's also entire books on holistics and pets, so that may be something to investigate further as well. One book that I really like is entitled The Holistic Dog Book by Denise Flaim and it provides a really good introduction to holistics as a practice, if that's something you're interested in trying.
Also, I think you may see an improvement in his overall condition if you work to boost his confidence. Instilling confidence, most easily done through obedience training, really equips a dog with a coping mechanism, and this will help him deal with the situations and experiences he encounters throughout his life. Some destructive behavior is done to send a message of boredom, discontentedness, etc. This is not something your dog will be as likely to do if he views you as the alpha. So I would work on assuming the role of alpha in your relationship. Basic training classes are a wonderful way to accomplish this. If you've taken classes in the past or are familiar with training, then several five to ten minute training sessions each day, would work well. It's the act of being able to accomplish a command, and being rewarded for it that builds self esteem and since you're in charge, it reinforces your place as alpha.
Also, if you think boredom is a factor, you could try hiring a dog walker to visit during the afternoon or if you work locally, maybe you could visit on your lunch break. Or enroll him in a puppy day care one or two days a week.
Also, you'll want to rotate the toys, so they'll keep his interest. I would rotate every day or two, taking up her current toy and putting down a different one. Really, the only toys they'll use when you're not around are chewing toys, so don't waste your money on other sorts of toys to keep him occupied when you're not home.
One other type of toy that he may find appealing is a treat-dispensing ball. You fill the ball with treats and there's holes in the ball so when he rolls it just right, a treat comes out. This occupies the mind very well.
A scavenger hunt can be fun too. You can hide a toy or two, and some treats at random locations around your house right before you leave (make sure he's not watching you while you hide it all! If you have a fenced yard, let him out for a couple of minutes or let him hang out in the bathroom for a couple of minutes while you hide). Pick random places - a low window sill, on the seat of a kitchen chair - places that aren't obvious. And change them up to keep him guessing. (just be sure that he won't get stuck or hurt trying to get at the treats!) You can be inventive with the treats too - You can use baby carrots, hot dog bits, a toy with cream cheese or peanut butter inside. And just as you're walking out the door, let him loose to start his scavenger hunt. He'll find nice treats throughout the day and it will work his mind. After a few days, he'll have you all figured out and he'll know that your departure marks the start of his scavenger hunt. This will help neutralize your departure, since you'll be pairing it with something positive.
Another useful tool can be the television. Many dogs like to watch TV, especially when there's other animals. They make "petsitter" DVDs for this purpose, and Animal Planet can keep their attention too. If she's a TV watcher, he may appreciate this. Imagine how quiet the house must be when you're not home - the silence must be deafening. I have a pug who will sit right in front of the TV, tipping his head and wagging his tail at the animals on the screen. He'll do this for hours if you let him - he really enjoys it. So it's something to try.
I would also see if there's a way to limit his access to the areas he's made the holes for the next couple of weeks. Baby gates work wonders for this. Dogs are creatures of habit and if he's formed a habit of digging on the wall, then you'll need to break it - even with toys and walks, it may be too tempting in the beginning, so I would recommend limiting access for the time-being.
Also, to the best of your ability, keep a regular schedule. If you work erratic hours, see what you can do to have a friend, dog walker or neighbor let him out on a regular schedule (i.e. every few hours). I think you may find that he's more apt to be destructive on days when you work late, or when he goes a long time between going outside to play or walk. But if he's let outside to play on a regular basis, he'll learn to anticipate and expect this, and this too can really help - dogs are creatures of habit and they're the most emotionally stable when everything is constant in their life and scheduled. If you work the same hours every day, it makes things that much easier. But, if you need to go to a dinner meeting straight from work one day, just plan ahead and have someone let her out an extra time, or stop by briefly to take him for a quick walk.
Here's a couple of good sites about boredom and anxiety that you may find helpful: http://dogs.about.com/cs/disableddogs/a/ocd.htm http://dogs.about.com/cs/disableddogs/a/anxiety_one.htm http://www.dermapet.com/articles/art-18.html
I hope your dog is doing better soon! Don't hesitate to let me know if you run into any problems or have any additional questions!
****Please ACCEPT if my answer was helpful!****
*As experts, we do not get compensated for our time and efforts unless you "accept!"*