Would need much more history about the last 6 years of her life but does she only do this when you are gone away from home? Does she have known "Seperation Anxiety" issues when your gone?
I have good luck with using a horse can of spray product called NO CHEW for horses that chew wooden stalls and barns doors etc. Very nasty tasting and kind of sticky so it lasts. It totally stopped a dog many years ago from chewing up the red wood patio furniture. Check you local feed store for something like that.
I would get her some raw beef marrow and knuckle bones from the butcher at the market and give her one when you leave. When you come home put it in a bag in the fridge for tomorrow. Keeps the ants away. Also KONG toys stuffed with really tasty food treats work too. http://www.kongcompany.com
Hope that helps,