Family and former staff of former U.S. President George H.W. Bush will hold a brief ceremony on Monday morning at a Texas Air National Guard base outside Houston, putting his casket onto Air Force One for a final trip to Washington.
The Bush's family spokesman, Jim McGrath, posted the picture of the yellow Labrador retriever called Sully on Twitter with the caption "Mission complete".
Bush received Sully in June from America's VetDogs, a nonprofit organization.
The 41st president, who died Friday, made his affinity for fun socks known in the past several years, choosing bold patterns and bright colors to liven up his suits or chinos.
Sully will return to America's VetDogs in NY before joining the Water Reed National Military Medical Centre's Facility Dog Programme, KTRK-TV in Houston reported.
Afterward, Bush's body will be returned to Houston to lie in repose at St. Martin's Episcopal Church before burial Thursday at his family plot on the library grounds. An invitation-only funeral service is set for Wednesday at Washington National Cathedral.
President Donald Trump, who ordered federal offices closed for a national day of mourning on Wednesday, is to attend with first lady Melania Trump and other high-ranking officials.
George Bush will receive a state funeral.
Bush's service dog lies next to former president's casket
In April, after his wife Barbara died, Bush reportedly contacted John's Crazy Socks to see if they had any socks he could wear to her funeral.
At the presidential library on Saturday, people came to sign the memorial book in Mr Bush's honour, or lay flowers at the feet of his statue.
He was a decorated World War II fighter pilot, former head of the Central Intelligence Agency, and vice president to Ronald Reagan before winning the White House.
This file photo taken 28 April 1988, shows former US vice president George Bush (right) as he shares a laugh with Canada's former prime minister Brian Mulroney, outside Bush's residence in Washington, DC.
That was a time that saw the end of the Cold War as well as the United States' routing of Iraqi President Saddam Hussein's army in the 1991 Gulf War.
Bush had been in and out of the hospital in recent years, primarily due to the Parkinson's disease that Baker said hampered his body's ability to get rid of phlegm, often causing pneumonia. He wanted to avoid a war'.
Bush visits a tent camp for quake survivors on the outskirts of Islamabad, Pakistan, in 2006.
"By the time he got back here to Houston from his summer in Kennebunkport, I think he was pretty much ready to go". Other Bush family members are expected to be at the Maryland military base for the arrival.