Our Dog had Two Jobs:

Our lovely dog had two important jobs that she assigned to herself many years ago, when she came to live with us. One was obvious, you could never miss it: watchdog. The other was less obvious. In fact I watched her do it for years before I realized what she was up to. Here’s how it worked: I would come home to find a UPS box on the floor near the front door – my new coffee delivery, perhaps. Right away I would (as usual) walk the dog. As she passed the UPS package on the way to the front door, she would sniff and check out the box briefly but carefully. I never saw her check out any particular box more than once.
Years later it hit me – she had already seen these boxes before I got home! As a watchdog, she would have been all over the front of the house when my wife signed for the package. So why did I always see her check out each box? She was pointing it out to me, making sure I noticed any untoward change in the home environment. That was her second job.