Joe and Jill Biden have announced their family dog Champ has died, saying "our hearts are heavy today".
In a tribute, the US president and the First Lady said the 13-year-old German Shepherd was a "constant, cherished companion" in their "most joyful moments and in our most grief-stricken days".
The couple said the dog's strength had waned in his final months and that he passed away peacefully at home.
"Wherever we were, he wanted to be, and everything was instantly better when he was next to us," they said in a statement. He was also a favourite with the Bidens' grandchildren.
Champ was bought from a breeder as a puppy shortly after the 2008 election and spent his early years at the Naval Observatory, the US vice president's residence, during Mr Biden's eight years in the role.
Our family lost our loving companion Champ today. I will miss him. pic.twitter.com/sePqXBIAsE
— President Biden (@POTUS) June 19, 2021
He enjoyed chasing golf balls on the property's front lawn as well as racing the younger members of the Biden family in their backyard in Delaware.
Champ and a second German Shepherd, a rescue named Major, had moved to the White House with the Bidens in January.
But within six weeks of taking office, the dogs were briefly sent back to Delaware for extra training after Major, the younger of the pair, bit a member of White House security.
Major had displayed “agitated behaviour on multiple occasions, including jumping, barking, and ‘charging’ at staff and security”, according to CNN.
Mr Biden has had a long association with German Shepherds and has had the breed for pets since he was a child.
Major was fostered by the Bidens in March 2018 from the Delaware Humane Society - the US equivalent of the RSPCA. The family adopted him eight months later.
The White House insisted the dogs were well behaved and would return to Washington after a brief stint in Delaware. A second biting incident occurred shortly afterwards.
But it is not the first time that Major has caused trouble for the President.
In November, Mr Biden fractured his foot while playing with the lively canine in Delaware and had to wear a walking boot for a number of weeks.
The First Lady described being "obsessed" with getting the dogs settled into life at the White House after the inauguration in January.
"They have to take the elevator, they're not used to that, and they have to go out on the South Lawn with lots of people watching them. So that's what I've been obsessed with, getting everybody settled and calm," she said.
It is unclear if the Bidens will get a second dog to keep Major company. The First Lady revealed in April that the couple have a female cat "waiting in the wings".
"Our family lost our loving companion Champ today. I will miss him,' Mr Biden wrote on Twitter.
The First Lady also paid tribute to the pet, tweeting: "RIP to our sweet, good boy, Champ. We will miss you always."