I have 2 dogs...one is a Saint Bernard/ Australian Shepard mix, and the other one is a Lab/Dalmation mix. Apparently they don't like it when we leave them alone. Between the both of them, they have chewed up :

3 extensioon cords, 2 landscaping lights and their cord, about 10 landscaping edging pieces, and have ripped off and chewed up 4 of our screens ON the windows. They carry entire tree branches around the yard too.  

Tell me that aint some damage !