Complex sentence: Various breeds of dogs have been used by the sports teams as mascots since the early 1900s, with several notable bull terriers like Sergeant Stubby and Hoya being used at football games in the 1920s, and a Great Dane in the 1940s.
Split into simpler sentences: Various breeds of dogs have been used by the sports teams as mascots since the early 1900s. Several notable bull terriers like Sergeant Stubby and "Hoya" were used at football games in the 1920s, as was a Great Dane in the 1940s.