George HW Bush’s service dog Sully has been photographed lying next to his master's casket ahead of his funeral.

On Sunday, family spokesman Jim McGrath shared the image of the yellow Labrador on Twitter, where he wrote: “Mission complete.”

In the photo, Sully wears his vest and appears to be sleeping in front of the flag-draped casket.

The photo was also shared on Sully’s Instagram @sullyhwbush, where the dog has more than 96,000 followers.

Sully, who is named after former airline pilot Chesley B “Sully” Sullenberger III, was appointed to the 41st president in June.

He was trained by nonprofit America’s VetDogs, and can perform a two-page list of commands.

Since joining the Bush family, the dog had accompanied Bush everywhere, and will continue to do so once more as Bush’s remains travel back to Washington DC ahead of a state funeral, according to CNN.

After Sully’s final mission is complete, the highly trained service dog will return to service to help other veterans at Walter Reed National Military Medical Centre, according to former president George W Bush.

“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,” Bush wrote on Instagram.

Following the 94-year-old’s death on Friday, his remains will be flown to the Joint Base Andrews military facility in Maryland.

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