Bolivar first appeared in 1936 in the animated short Alpine Climbers. He and Pluto rescued Mickey Mouse and Donald Duck from wild animals. He was then introduced in the Donald Duck comic strip in 1938.
Bolivar has been shown in various roles, some of them antagonistic to Donald Duck and his nephews, others being their pet. Most recent stories, however, maintain showing him as Donald's pet.
It's thought that the editors of the Donald Duck strip though that the dog being named Bolivar would be seen as a slight against Simon Bolivar, a Venezuelan patriot of the time. For a time, Bolivar's name was changed to "Bornworthy", though later strips reverted his name to Bolivar, (with the occasional nickname of "Bernie"). He also has a child, named Behemoth, who first appeared in the 1940s Taliaferro strips. He is often shown as being friendly with Pluto, as he was in his initial appearance.