Hi XXXXXXXXXX~
Sounds like you have a dog who is showing some anxiety by destroying things when left alone.
If this were my dog, the first thing I'd do would be to invest in a stronger crate/kennel for her when you're not home. Places like Petco and PetSmart have kennels that are made especially for the dog who is a bit of Houdini about getting out of them. They have stronger doors and latches and I've found that my rescue pits have a hard time breaking free.
You might also want to look into different products that work specifically on anxiety dogs. In my experience, I've used two exclusively:
Melantonin is an over-the-counter drug that can be used to treat some anxiety issues in dogs. The dose you would give would be up to 3 mg given orally whenever necessary up to every 8 hours. More information can be found here: http://www.petplace.com/drug-library/melatonin-melatonex/page1.aspx , which includes risks, warning signs to watch out for and other bits of useful information.
Try a DAP collar. These are collars that are impregnated with a man-made version of the dog appeasing pheromone, which is a pheromone that nursing bitches give off to their pups to help them feel calm and secure. It's something that humans can't smell, but it has an amazing effect on dogs with anxiety and other issues. Although you can find them at your vet's office..you can also find them online at places like Amazon.com and Ebay for much cheaper. Just make sure they're DAP brand, as they seem to work better than some other versions.
I usually start with the collar and then add in the Melatonin if needed.
If none of these things work, you might want to talk to your vet about a stronger sedative for when you are away from the house for short periods (like on the weekends)...and you might want to look into doggy daycare for when you're away at work.
Another option (and I don't know how agreeable you are to this), but since having the cat with her helped for a while...getting her a canine companion might help ease her anxiety and give her something to do while you;re gone, other than finding ways to escape.
I hope this helps!!
It's hard to say what triggered this behavior after all this time.
I do suggest you NOT put a muzzle on her while you're not at home. It's not safe to have a dog muzzled when no one is supervising them.
You also might want to look into talking to a behaviorist. They can come out, observe your dog and really get a feel for what is going on with her. They might even give you some tips on how to help her feel more at ease when you leave the house.
Certified Veterinary Technician
Associates Degree in Veterinary Technology. State and Nationally certified.