Sully, the service dog of former President George H.W. Bush, sits alongside Valerie Cramer as they visit the flag-draped casket of President Bush in the Capitol Rotunda in Washington, Tuesday, Dec. 4, 2018. (AP Photo/Patrick Semansky)

Sully, former President George H.W. Bush's service dog, pays his respect to President Bush as he lie in state at the U.S. Capitol in Washington, Tuesday, Dec. 4, 2018. (AP Photo/Manuel Balce Ceneta)

Sully, the service dog of former President George H.W. Bush, sits near the flag-draped casket of President Bush as he lies in state in the Capitol Rotunda in Washington, Tuesday, Dec. 4, 2018. (AP Photo/Patrick Semansky)

Sully, the service dog of former President George H.W. Bush, sits near the flag-draped casket of President Bush as he lies in state in the Capitol Rotunda in Washington, Tuesday, Dec. 4, 2018. (AP Photo/Patrick Semansky)

Sully, former President George H.W. Bush's service dog, walks to the Capitol Rotunda to pay respect to President Bush as he lie in state at the U.S. Capitol in Washington, Tuesday, Dec. 4, 2018. (AP Photo/Manuel Balce Ceneta)

Sully, former President George H.W. Bush's service dog, pays his respect to President Bush as he lie in state at the U.S. Capitol in Washington, Tuesday, Dec. 4, 2018. (AP Photo/Manuel Balce Ceneta)

Sully, former President George H.W. Bush's service dog, walks to the Capitol Rotunda to pay respect to President Bush as he lie in state at the U.S. Capitol in Washington, Tuesday, Dec. 4, 2018. (AP Photo/Manuel Balce Ceneta)

Sully, former President George H.W. Bush's service dog, pays his respect to President Bush as he lie in state at the U.S. Capitol in Washington, Tuesday, Dec. 4, 2018. (AP Photo/Manuel Balce Ceneta), APTOPIX

Sully, former President George H.W. Bush's service dog, pays his respect to President Bush as he lie in state at the U.S. Capitol in Washington, Tuesday, Dec. 4, 2018. (AP Photo/Manuel Balce Ceneta)

Sully, former President George H.W. Bush's service dog, pays his respect to President Bush as he lie in state at the U.S. Capitol in Washington, Tuesday, Dec. 4, 2018. (AP Photo/Manuel Balce Ceneta)

Sully, the service dog is seen as people pay respects, as the remains of former US President George H. W. Bush lie in state in the US Capitol's rotunda December 4, 2018 in Washington, DC. - The body of the late former President George H.W. Bush travelled from Houston to Washington, where he will lie in state at the US Capitol through Wednesday morning. Bush, who died on November 30, will return to Houston for his funeral on Thursday. (Photo by Alex Edelman / AFP)

Sully, the service dog is seen as people pay respects, as the remains of former US President George H. W. Bush lie in state in the US Capitol's rotunda December 4, 2018 in Washington, DC. - The body of the late former President George H.W. Bush travelled from Houston to Washington, where he will lie in state at the US Capitol through Wednesday morning. Bush, who died on November 30, will return to Houston for his funeral on Thursday. (Photo by Alex Edelman / AFP)

Sully, the service dog is seen as people pay respects, as the remains of former US President George H. W. Bush lie in state in the US Capitol's rotunda December 4, 2018 in Washington, DC. - The body of the late former President George H.W. Bush travelled from Houston to Washington, where he will lie in state at the US Capitol through Wednesday morning. Bush, who died on November 30, will return to Houston for his funeral on Thursday. (Photo by Alex Edelman / AFP)

Sully, the service dog is photographed by media as people pay respects, as the remains of former US President George H. W. Bush lie in state in the US Capitol's rotunda December 4, 2018 in Washington, DC. - The body of the late former President George H.W. Bush travelled from Houston to Washington, where he will lie in state at the US Capitol through Wednesday morning. Bush, who died on November 30, will return to Houston for his funeral on Thursday. (Photo by Alex Edelman / AFP)

Sully, the service dog, is seen as people pay respects, as the remains of former US President George H. W. Bush lie in state in the US Capitol's rotunda December 4, 2018 in Washington, DC. - The body of the late former President George H.W. Bush travelled from Houston to Washington, where he will lie in state at the US Capitol through Wednesday morning. Bush, who died on November 30, will return to Houston for his funeral on Thursday. (Photo by Brendan Smialowski / AFP)

Sully, former US President George H. W. Bush's service dog, lays in the Rotunda of the US Capitol as people gather to pay respects as the remains of the former president lies in state December 4, 2018 in Washington, DC. - The body of the late former President George H.W. Bush travelled from Houston to Washington, where he will lie in state at the US Capitol through Wednesday morning. Bush, who died on November 30, will return to Houston for his funeral on Thursday. (Photo by Alex Edelman / AFP)

Sully, the service dog, lies next to the casket while, people pay respects, as the remains of former US President George H. W. Bush lie in state in the US Capitol's rotunda December 4, 2018 in Washington, DC. - The body of the late former President George H.W. Bush travelled from Houston to Washington, where he will lie in state at the US Capitol through Wednesday morning. Bush, who died on November 30, will return to Houston for his funeral on Thursday. (Photo by Brendan Smialowski / AFP)

Sully, the yellow Labrador retriever who was former President George H.W. Bush's service dog, stands next to Bush family members during a departure ceremony at Ellington Field Monday, Dec. 3, 2018, in Houston.(AP Photo/David J. Phillip, Pool)

Sully, the service dog of former President George H.W. Bush looks back as he arrives at Andrews Air Force Base in Md., Monday, Dec. 3, 2018, accompanying the casket of Bush who died Friday at age 94. (AP Photo/Susan Walsh)

Family members, with Sully, arrive before the flag-draped casket of former President George H.W. Bush is carried by a joint services military honor guard to the hearse, Monday, Dec. 3, 2018, at Andrews Air Force Base, Md. (AP Photo/Alex Brandon, Pool)