I've got a 12 year old black lab too, but she doesn't have problems with such things. But she is still quiet energetic. In fact...
... she usually doesn't ruin my stuff but this morning I found this surprise in my living room:

Someone had a field day with my yarn...
She tried to blame the cat but I know the guilty face when I see it...

Looks like old dogs can be just as naughty as young pups!