George HW Bush’s dog Sully has reached the end of his mission to serve the former president, but will accompany his owner on one last journey before his service is up.

Mr Bush died on November 30, aged 94.

A photo of the two-year-old yellow labrador lying by his late owner’s coffin was posted to Twitter by Mr Bush’s spokesman, Jim McGrath, with the caption, “Mission complete”.

The moving tribute to the 41st US president has been widely shared across social media, with the original post attracting more than 230,000 likes.

Sully travelled with Mr Bush’s body on the Air Force One plane as it was flown from Texas to Washington DC, where it will lie in state ahead of a national day of mourning on Wednesday.

Air Force One has temporarily been named Special Air Mission 41 until Wednesday, in honour of Mr Bush.

As Mr Bush’s body was carried from the funeral home by Secret Service members, Sully walked along in the procession.

Tweet from @GeorgeHWBush

Sully will remain by his owner’s side throughout the mission, accompanying his body when it is transported by train back to Texas for a state funeral on Thursday.

Mr Bush will be laid to rest at the George HW Bush Presidential Library Center in College Station, Texas and will be buried alongside his wife, Barbara who died in April, and daughter Robin, who died of leukemia in 1953.

Sully was trained by America’s VetDogs, an organisation that provides service dogs to former military members requiring special assistance.

Mr Bush had been using a wheelchair since 2012, after being diagnosed with a form of Parkinson’s disease.

Sully was assigned to Mr Bush in June, being specifically paired with the former president to suit his needs.

The two-year-old assisted Mr Bush by opening doors and retrieving objects but was also a beloved companion, accompanying him when he voted for the final time.

Sully has generated a large following on social media. An Instagram account dedicated to documenting his life attracted more than 140,000 followers.

Sully will return to America’s VetDogs later this week before joining a force of canines tasked with assisting wounded soldiers and active personnel with physical and occupational therapy at the Walter Reed Bethesda Military Medical Centre.

In a repost of the photo of Sully by his father’s coffin, George W Bush said the dog would be missed.

“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,” Mr Bush said.

-ABC