The first suggestion of having a mascot worthy of Louisiana (SLI) was in 1921.
This was the year that the University of Louisiana experienced it's first name change. SLII was dropped in favor of SLI, with the only modification being the deletion of the term "Industrial"
The suggestion for a mascot came from the students, and indeed, the students did start calling themselves the "Bulldogs" as early as 1921.
It took two years (1923) before the school offically and unanimously voted to adopt "Bulldogs" as the SLI mascot. The name "Bullpups" was also adopted in 1923 to be used for second teams.
That same year was the first ever published illustration of the SLI Bulldog mascot.This is the picture from 1923 (L'Acadien) shown above.