can you not put something on or in there bedding to stop them shredding it? something that dogs dont like the taste of but wouldnt do any harm to there skin or eyes?
when my whippet was small it had a habit of chewing the chair legs, table legs and scratching the carpet up i used to sprinkle pepper on them to stop it, they soon learn not to bother it again.
its just a case of trying to find something suitable.