If a man wants a friend in Washington, goes the saying, get a dog. So the news that President Biden has fired his dog — Major — strikes us as a mistake. It’s bad enough that the president permits his dog to be cashiered just because he bit a couple of Secret Service agents. It’s what the error says about the presidential character. If Mr. Biden can’t find it within himself to back his own dog, what job in the administration is safe?

The news broke in a backhanded kind of way. One day Major was bounding around the White House trying to protect the president from the Secret Service. The next day he was gone. The next thing you know, a three-month-old German Shepherd named Commander fetches up on the social mediums and the wires are reporting that there’s a “new top dog” at the White House — supposedly a gift from the presidential brother.

What kind of appointment process is this? The presidential dog is usually one of the most important in any administration — ranking ahead of the vice president, Kamala Harris notwithstanding. Vice President Nixon’s dog, Checkers, kept a judicious silence during a scandal that otherwise might have cost Nixon the vice presidency itself. And FDR defended his dog, Fala, when the President was accused of sending the Navy to retrieve the pooch from Alaska.

The fate of Major illustrates another adage of the modern presidency: it’s not the crime, it’s the coverup. Judicial Watch — the group known for its bloodhound-like pursuit of Senator Clinton’s lost e-mails — learned that Major played a more active role in White House security than initially reported. The group smoked out communications among Mr. Biden’s protection detail showing the canine’s policy of bite first, ask questions later had put him in the, um, doghouse.

It turns out Major interpreted his role as to be a watchdog. His dedication was such that, according to reporting in the New York Post, Secret Service agents had to be warned not to lose their composure: “Panicking or running” was risky, an advisory email indicated. Agents were instead urged to “stand your ground and protect your hands/fingers by placing them in your pockets or behind your back.”

Agents complained of ripped overcoats, bruises and even puncture wounds. Judicial Watch learned that in early March Major had bitten agents eight days in a row, a finding the group called “disturbing.” The administration had previously acknowledged only two isolated biting incidents. The absence of candor from the White House on this head is disappointing, if not necessarily surprising.

Major’s departure from the White House was handled with the kind of secrecy that is generally reserved for high-profile political embarrassments. He was sent back to Delaware for retraining, though, the Post reported, it was described by the White House as “a prearranged visit with family friends.” Yet Major returned unreformed, and another biting incident on the South Lawn prompted the end of his tenure in the executive branch.

We take a particular interest because, in historian Janet Steele’s telling, it was the editor of The New York Sun, Charles Dana, who in 1882 annunciated the very nature of news, one that bears on why no editor lost sleep over these hapless Secret Service agents. “When a dog bites a man, that is not news,” Mr. Dana declared, “but when a man bites a dog, that is news.” Something for Commander — and commander in chief — to remember.