Thanks for posting that info as well! Very interesting.Before you implement any approach to address what you've labeled a resource guarding issue, I'd strongly suggest you do two things: (1) As DoubleHaul suggested, whenever a dog has a sudden behavioral change, it's worth looking into whether some physical or health issue might be involved. (2) PLEASE read this post on Patricia McConnell's blog about resource guarding treatment and prevention: http://www.patriciamcconnell.com/the...and-prevention
If you're not familiar with Patricia McConnell, you can find more information about her here: http://www.patriciamcconnell.com/about-patricia. Her books and blog are wonderful reading. Her dissertation research was on communication between sheep herders and their dogs, she's a Certified Applied Animal Behaviorist with many years in private practice (including working with 100s if not 1,000s of dogs with resource guarding issues), is well versed in current scientific literature on dog behavior and learning, has bred border collies and trained them for herding, and above all, is thoughtful and not dogmatic about all things dog. If I had a dog with a behavioral issue, her work is the first place I'd go to begin to seek guidance. Like you, she lives in Wisconsin. I don't think she's in private practice any longer, but the business she founded is still alive and well and could be a great place to seek a consultation if you think that's appropriate: http://www.dogsbestfriendtraining.com.
Good luck with your pup.