Another story with a happy ending. (I luv happy endings!) The Chocolate Lab, who we now know was named "Hershey" has been reunited with her family. Being new to Westford, they weren't sure how to go about reporting their dog as being missing. Yesterday evening, they dropped by the Town Office, and Nanette pulled up this blogsite. After seeing the photo's, she confirmed that it was her dog, and they then gave me a call.
Thanks to everyone who helped out, from the very kind resident who first found Hershey and called me, and to all those who sent me emails on possible leads.