old dog acting up

Question
I have a 13 year old lab sharp pei mix who has been fixed since she was like six months old, Ive had her her whole life (since I was 7, am now 21) and for the past three weeks shes been tearing up my house! shes never done this before but now shes getting into the garbage and chewing up my couch and pulling my clothes out of my dresser and ripping those up too!!! I don't understand whats gotten into her, and whats worse is when i come home before i even see the mess i can tell shes done something because she pouts up to me!! she knows its bad or she wouldn't act guilty!!! I don't know what to do! i've had her 13 years and i love her but its getting stressful!!! i want to know why shes being a brat all of the sudden!

Answer
Such a behavior change has a cause.  Unless you can think of some big change, how long she is left alone, who lives in the house, etc., have the vet gave her a good check up. perhaps even blood work.  If that doesn't turn up anything, get back with me on any other changes that could have taken place.  

And please, don't punish her for what may not be her fault.  She doesn't know it is bad, only that you get angry every time you come home.