Boxer Who Chews EVERYTHING

At 5 months they are still in that chewing stage.

I will keep your dog in a kennel or crated area or fenced in area outside when you or anyone else isn't playing with him. When you have time to supervise him, then let him out and watch him praise him for chewing on the right things. I would give him walks and play with him outside when the weather permits. They do outgrow the chewing stages, however sometimes it takes up to 1year to stop the major chewing on other things.

At 6 months you might want to get some trainings. You can always get books on dogs/training or go and get the training elsewhere.

You should look into crate training her. Not only does it help prevent things like this, it is also great for emergencies and vetting if they are already used to being crated.
Also long daily walks.

At home crate trianing,2 week board and train,or doggy day care! :)

You can not expect a 5 month old puppy (or a puppy of any age) to know the difference between the right thing to chew on and the wrong. I used to teach obedience classes and what I always told my students was, no matter what they chew up or pee on, you can't blame them... You should have been supervising in the first place. Think of it this way. Would you give your 2 year old child a magic marker and then turn him loose in an house that hadn't been childproofed? Bad idea.

With that being said, there are two things that need to happen. First, he needs to always be supervised. ALWAYS! If you can't watch what he is doing he should be in a crate, or outdoors (if you don't mind the fence being chewed). When he is inside with you, you should reward when he chews on the right thing and redirect when he chews on the wrong. By redirect, I mean use something to startle him from the behavior (like clapping, growling, stomping... not hitting) and then give him his toy.

The second thing that needs to happen is he is probably quite bored. You say that he is very smart, but you don't say anything about formal training. He needs something to keep his mind active. Another saying I've always used is, "if you don't give your dog something to do, he'll find something on his own, and you probably won't like it!" teaching a trick here and there is not the same as participating in formal obedience or agility training.

Ah, I just noticed that you have a female... Sorry, change everything above from he to she ;-)

Feel free to contact me if you have questions.
Good luck!
A.
Mom to two boys under the age of 2 and many dogs (some with titles in obedience, agility, and conformation!)

I will second the recommendation for crate training and daily walks. A tired dog is a good dog!!

Remember that she is loosing her puppy teeth right now and growing her adult teeth, so her gums are probably real sore. We were told to give our puppy an ice cube. Our dog didn't like it, but some do. Our puppy tried to chew everything but slowed down when he got older. We did use plenty of bones and the Kong. He would spend hours with each and that left him little time to chew on anything else. Also, if you catch her in the act, tell her no in your stern voice and then put a chew toy in her mouth right away and if she starts playing with that give her lots of praise. I know it is hard, but try not to yell at her unless you actually catch her. To yell at her later will confuse her.