Bush family spokesman Jim McGrath on Sunday night honored the service dog who accompanied George H.W. Bush during the former president's final months.
Sully the dog will be travelling with the casket on the flight from Texas to Washington DC on Monday.
To honor the former president, the global nonprofit Points of Light, founded by Bush, invited the public to celebrate Bush by giving a day of service in his memory. Bush's family has not said who will speak at the service. The public can pay their last respects during public viewings.
Social media users thanked Sully for his services and commented on his and dogs' loyalty generally towards their owners.
Members of the House and Senate will take part Monday evening in a ceremony at the U.S. Capitol as the casket of former President George H.W. Bush arrives.
David J. Phillip Pool AP
Not all USA presidents have been fond of dogs though: John F Kennedy was allergic to dogs, and Donald Trump does not have one.
Both Bush's wife Barbara, the former first lady who died in April, and their daughter Robin, who died of leukemia as a child, are laid to rest on the library's grounds.
He died aged 94 in Houston, Texas.More news: Kartarpur Corridor: Harsimrat Kaur Badal and Hardeep Singh Puri leave for Pakistan