A photo tweeted on Sunday showed former President George HW Bush's service dog, Sully, lying in front of the 41st president's casket.
The Bush family's spokesman, Jim McGrath, shared the moving picture with the caption: "Mission complete."
Bush's family posted a picture of Sully on Instagram, saying: "As much as our family is going to miss this dog, we're comforted to know he'll bring the same joy to his new home, Walter Reed, that he brought to 41."
Sully was assigned to Bush in June to provide support in his daily activities, according to America's VetDogs — an organisation that matches veterans and service dogs.
The canine will go back to America's VetDogs centre on Long Island, where he will stay over Christmas before he is moved to the Walter Reed National Military Medical Center's Facility Dog Program in Bethesda, Maryland.
The company's president and CEO, John Miller, said in a statement:
"Our thoughts and prayers are with the entire Bush family during this difficult time. It was truly an honor to have provided service dog Sully to be by the president’s side for the past several months. As a true patriot and a visionary, President Bush will forever be viewed by people with disabilities and their families as a hero through his efforts to enact the Americans with Disabilities Act. We are forever grateful to his service to the American people."
Bush died Friday aged 94 and will be laid to rest Thursday afternoon at his presidential library in College Station, Texas.
US President Donald Trump called Bush a "truly wonderful man and will be missed by all".