"During the 1977 state visit of Mexico, presidents Carter and José López Portillo descended the staircase without a military escort or the performance of "Hail, America". However, Misty Malarkey Yin Yang, Amy Carter's cat, escaped from its room and unexpectedly joined presidents Carter and Portillo, according to one source "marching down the stairs most regally and surefooted" at the head of the group."
(from https://en.wikipedia.org/wiki/Hail,_America)