Vahanas of Ganesha
The earliest Ganesha images are without a vahana (mount/vehicle). Of the eight incarnations of Ganesha described in the Mudgala Purana, Ganesha has a mouse in five of them, uses a lion in his incarnation as Vakratunda, a peacock in his incarnation of Vikata, and Shesha, the divine serpent, in his incarnation as Vighnaraja. Of the four incarnations of Ganesha listed in the Ganesha Purana, Mohotkata has a lion, Mayūreśvara has a peacock, Dhumraketu has a horse, and Gajanana has a rat. Jain depictions of Ganesha show his vahana variously as a mouse, elephant, tortoise, ram, or peacock.
Ganesha is often shown riding on or attended by a mouse or rat. Martin-Dubost says that the rat began to appear as the principal vehicle in sculptures of Ganesha in central and western India during the 7th century; the rat was always placed close to his feet. The mouse as a mount first appears in written sources in the Matsya Purana and later in the Brahmananda Purana and Ganesha Purana, where Ganesha uses it as his vehicle only in his last incarnation. The Ganapati Atharvashirsa includes a meditation verse on Ganesha that describes the mouse appearing on his flag. The names Mūṣakavāhana (mouse-mount) and Ākhuketana (rat-banner) appear in the Ganesha Sahasranama.
The mouse is interpreted in several ways. According to Grimes, “Many, if not most of those who interpret Gaṇapati’s mouse, do so negatively; it symbolizes tamoguṇa as well as desire”. Along these lines, Michael Wilcockson says it symbolizes those who wish to overcome desires and be less selfish. Krishan notes that the rat is destructive and a menace to crops. The Sanskrit word mūṣaka (mouse) is derived from the root mūṣ (stealing, robbing). It was essential to subdue the rat as a destructive pest, a type of vighna (impediment) that needed to be overcome. According to this theory, showing Ganesha as master of the rat demonstrates his function as Vigneshvara (Lord of Obstacles) and gives evidence of his possible role as a folk grāmata-devatā (village deity) who later rose to greater prominence. Martin-Dubost notes a view that the rat is a symbol suggesting that Ganesha, like the rat, penetrates even the most secret places.