With this said, there are other issues here. A young dog like this that’s doing this almost always needs more physical exercise and mental exercise. It also needs to learn to relax in the environment it is in.
Each of these issues need to be addressed separately
1 - When a dog is introduced to a muzzle, it always needs to be conditioned to the muzzle. We have free streaming videos on our web site about this. Use the search function to find it in our video on demand. We had a lady a few weeks ago who just slapped a muzzle on and left. The dog went through 3 muzzles where it got them off and then chewed them up. That’s an owner problem not a muzzle problem. She should have conditioned the dog to the muzzle.
2 - Take your dog for some long walks or have it chase balls to get it a little tired.
3 - Better yet, when you home keep it in a dog crate in the house and use a chain link kennel outside. Control the dogs environment.
4 - You can exercise the dog's mind as well as it's body. The best way to do this is with training. The best training method is marker training. This is operant conditioning. I wrote a free article explaining it. We also have a number of DVDs on this: