Crystal became an excavator when she was about 10 months old and my wife was away for 3 weeks on her annual trip back home. I believe it was stress related. She'd only been with us 5 months then and it mainly happened when I too had to leave her, perhaps for only an hour but I think she got perplexed as we are both retired and she does get constant company. A combination of the spray and lots of fuss and reassurance seemed to work. Ocassionally she has spasmodic tendencies for wall licking. This variant is less destructive and seems to be an attempt to gather nutrients from the paintwork, or add variance to the decoration? She's obviously been an architect in a previous incarnation and feels the need to keep her paw in...
Examples of her handywork appear below;