In the annals of presidential campaign coverage, I am an asterisk, and a tiny one at that - the journalist who unearthed the story of how Mitt Romney once drove to Canada with his dog Seamus in a carrier strapped to the roof of the family station wagon. In the nearly five years that have passed since I dug up that golden nugget, there’s been so much chatter about the anecdote that “Romney” and “dog” have become inseparable dance partners in Google searches entered around the world. (In just one sample week last month, that search snagged hundreds of fresh Web mentions.) Still, I have refrained from writing more about the Romneys’ Irish setter and his bout of highway-borne gastric distress. The reason? I dread the thought that Seamus might somehow make it into the lead paragraph of my eventual obituary.

Yet, here we are at the start of another primary season, with Romney once again awaiting the verdict from New Hampshire that could sink or propel the presidential ambitions he’s harbored at least since his father’s were dashed in 1968. And here we are, once again, watching the media and blogosphere — even the sober Wall Street Journal — fixate on Romney’s treatment of his dog nearly three decades ago. I’m wading in again because I’ve come to believe that the endurance of the Seamus story sheds fascinating light on our media and political cultures. Just as interesting is the light it sheds on Romney himself.