Bush's son President George W. Bush named Roberts chief justice in 2005. He died Friday at his Houston home at age 94, and his body is heading to Washington for a state funeral.
Sully, a yellow Labrador who became Bush's service dog in June, will make one last trip ith the former president, accompanying his casket to Washington, D.C., a trip McGrath says has the call sign is "Special Air Mission 41".
The White House announced on Saturday that Trump and first lady Melania Trump will attend Wednesday's service at the National Cathedral.
The Capitol will be open for dignitaries and the public to pay their respects through early Wednesday, with visitors allowed to walk past Bush's casket.
On Thursday, a private funeral service with about 1,200 invited guests will be held at the church starting at 10 a.m. CST.More news: Samsung's folding screen tech has been stolen and sold to China
A ceremony will be held at the train station as Bush's casket is loaded onto a Union Pacific train. Mulroney was prime minister from 1984 to 1993; Bush was president from 1989 to 1993.
Jeb Bush, sone of the 41st president and the former governor of Florida, retweeted the photo, with the simple words: "Sully has the watch". The casket will be in a auto with Plexiglas windows to allow people to see it during the trip, according to family spokesman Jim McGrath.
His remains will arrive in Washington on Monday, and he will lie in state at the Capitol through Wednesday.
Millie was famously referenced during the 1992 presidential campaign, when Bush said, of Bill Clinton and Al Gore, "My dog Millie knows more about foreign affairs than these two bozos".