The Lesser Dog symbolizes the Forerunner, sent ahead of the Lord to prepare His way and announce His coming. In antiquity, the main character of this small constellation was Procyon itself — its name literally means 'before the Dog', because it appears before Sirius, the main star of the Greater Dog. Therefore the Lesser Dog is not so much an independent hero of the heavenly picture, but the one who comes first and points to the One who follows — a precise image of John the Baptist before the appearance of Christ.
Full interpretation
Verifiable historical, etymological and topographical statements are accompanied by sources. The theological conclusions are the project’s interpretation according to its published methodology.
The most ancient reliable meaning of the Lesser Dog is contained in the name of its main star, Procyon. The Greek Prokyon literally means 'before the Dog', 'coming before the Dog'. Originally this name referred to almost the entire small celestial object, and the name 'Lesser Dog' became fixed later. Procyon rises before Sirius and therefore serves as a natural heavenly forerunner of the brighter star.[Kunitzsch & Smart][IAU · имена звёзд]
That is why the main image here is not 'a little dog', but the One who goes before.
This remarkably corresponds to John the Baptist. He appeared before Christ, but his entire ministry was directed not at himself. He was a voice that said: He who comes after me is greater than I. His purpose was to prepare the way of the Lord and point people to Him.
Moreover, this sequence is repeated directly in the heavens. First Procyon appears — 'the one who goes before', then Sirius comes — the brightest star in the night sky. And within the Greater Dog itself, before Sirius lies another star — Mirzam, whose ancient Arabic name is associated with 'announcing, proclaiming'. Thus the heavenly sequence itself seems to emphasize twice one thought: the coming of the Great One is preceded by proclamation.