George H.W. Bush's service dog Sully in the Capitol Rotunda on December 4, 2018

The heartbreaking viral image of Sully lying next to the 41st president’s coffin in Houston on Sunday, December 2, 2018 is pictured above

Sully is then expected to be transferred to the Walter Reed National Military Medical Center’s Facility Dog Program in Bethesda, where canines help wounded veterans as they undergo physical and occupational therapy

America’s VetDogs, an organization which pairs specially trained service dogs with wounded veterans, will return Sully to its Smithtown, New York headquarters, where he will stay for the holiday season

John Miller, President and CEO of America's VetDogs said, it was truly an honor to have provided service dog Sully to be by the President's side for the past several months.

Sully (seen above in this undated file photo posted to Instagram) will continue his service to America after the death of the 41st President

George H.W. Bush's service dog Sully was among the dozens who gathered to pay their respects to the late president as his casket lies in the Capitol Rotunda on December 4, 2018

The pup wore a mournful look on his face at the somber scene, though witnesses around Washington, DC, say Sully has been cheerful during his visit to the capital

Former President George H.W. Bush will lie in state until Wednesday-5th December 2018, when his casket is brought to Washington National Cathedral for a memorial service, his service dog Sully visits his casket in the Capitol Rotunda, pictured.

Sully is seen above with the former President in this undated image posted on social media

After news broke of Former President Bush’s passing on Saturday, December 1, 2018 America’s VetDogs tweeted a statement, saying: ‘America’s VetDogs is deeply saddened by the loss of President George H.W. Bush. Our condolences go out to the Bush family at this time.’ The tweet was attached to an image showing Bush being pushed in a wheelchair while holding a leash as Sully walks beside him

Former President George H.W. Bush’s official Twitter account posted an image of Sully and former President, Bill Clinton, on June 25 after Sully’s arrival. The tweet read: ‘A great joy to welcome home the newest member of our family, "Sully," a beautiful - and beautifully trained - lab from America’s VetDogs'

Former President George H.W. Bush's service dog Sully paid a visit to his late owner's casket in the Capitol Rotunda on Tuesday morning, December 4, 2018, as dozens gathered to pay their respects to the late president, who will lie in state until Wednesday morning

Sully, who was cast into the spotlight when a photo of him lying by his late owner's casket went viral over the weekend, drew the attention of photographers as he waltzed into the Rotunda 

The yellow Labrador Sully gifted to former President Bush Sr. in June wore an American flag-themed service animal vest while visiting the Capitol

Sully laid patiently in front of the flag-draped casket as dozens of mourners looked on during the somber occasion

After leaving the rotunda, Sully took a moment to pose with fans in Statuary Hall, including Former United States Secretary of Homeland Security Tom Ridge (pictured)

The former President George H.W. Bush had a form of Parkinson's disease, and Sully could open doors, pick up items and summon help. Sully with President Bush Sr. in Walker's Point, Bush Estate, pictured.

Sully was given to the elder Bush by America’s VetDogs, a New York-based nonprofit group which provides service dogs to veterans in need. In this instagram photo in Kennebunkport, Maine: My best friend has gotten some pretty rad socks, I'm rather a fan.

As he came into the room, Sully looked up at a photographer crouching on the ground to capture the pup's entrance

SullyHWBush nothing like being curled up on a comfy couch reading a good book, pictured in Kennebunkport, Maine

He is a specially trained dog who is capable of following a lengthy list of commands, including answering the phone and fetching items. The Bush family has grown especially close to the dog, as evidenced by an Instagram post by former President George W. Bush.  As much as our family is going to miss the dog, we're comforted to know he'll bring the same joy to his new home, Walter Reed, that he brought to 41,' the 43rd President wrote on Instagram.