To understand the depths of her sorrow, it's best to understand the source of her pain, a big blond bear of a dog with an unimaginably large head, snowshoe-sized paws, and a habit of making such a racket whenever he sprawled on the floor that he sounded like a building tumbling down.
Otis was a golden retriever, but never the type to bound across an open field after a ball. "He'd chase it maybe once, then just stand and pose," said his lifelong partner, Elizabeth Warren.
What Otis preferred was to variously lumber and meander through the Cambridge neighborhood where he didn't so much live as preside. There were hills to climb, people to greet, and a favorite body of water, Fresh Pond, to slowly circle in the first light of the morning and as the last red light faded from the evening sky. This was Otis's world.
He was a virtually inseparable companion to Warren and her husband, Bruce Mann — a serene, noble presence in their offices at Harvard University, on errands, and on the kitchen floor, where Warren would always run her fingers absently through his fur as she spoke on the phone.
Otis went to Washington with Warren during the depths of the financial crisis, and he loved it, not because it transformed his master into a national figure, but because their apartment building had elevators, meaning he didn't have to negotiate any pesky stairs.
He was with Warren in fall 2011 when she declared her campaign for the Senate. He was there as controversies flared, as accusations were leveled, as attack ads filled the airwaves. Polls rose and fell, criticisms alternated with compliments, but always there was Otis, blinking excitedly as Warren came through the door at the end of the day and always ready for a walk.
Later each night, they would park themselves on the living room couch, Warren in the middle, her husband to her left, Otis sprawled to her right, his cannonball head resting on her leg as he slept through their favorite TV shows.
Otis loved Halloween because of all the kids who would come to his door and inevitably want to pat him. But this most recent Halloween was different. Otis had been diagnosed with lymphoma in the spring. The chemotherapy treatments that had worked at first were losing their effectiveness. Warren, in the throes of the campaign, tried to will away the inevitable.
As kids came to the door that night, Otis watched from the kitchen floor, too weak to get up. When the last of the visitors had left and the lights were turned off, Mann embraced Warren and told her it was time to let him go. All she could do was cry.
I called Warren after her victory to see if she wanted to talk about this quiet loss in the final days of a very public campaign. It hurt her to talk about, but in an hour-long phone call this week, one filled with her laughter and her tears, she did.
She described "the white fur ball with big feet" that arrived at her house 7½ years ago, the casual way he would approach his many admirers, how the ground used to all but shake from his heavy gait.
"It's the lack of complication," Warren said. "I could spend time just running my hands through Otis's coat, drawing circles in his short fur, and thumping him on the side, his big hollow chest, you know that sound. It's possible to get lost in there. And that's what I needed."
On Nov. 1, in the closing days of the campaign, Mann and Warren brought Otis to Angell Memorial Hospital and sat on the floor as a veterinarian euthanized their uncommonly dignified dog.
Five days later, Warren made history in Massachusetts.
But what she wouldn't give for one more lap of Fresh Pond with Otis, another afternoon of him snoring on the kitchen floor, a final evening on the couch. It's the misery of ever loving a dog.
Brian McGrory is a Globe columnist. He can be reached at firstname.lastname@example.org.