Not quite an animal, but perhaps examples of metamorphosis could be equally insightful.
"An image of a rat. Raigo was a stern man, a priest whose duties included maintaining discipline among the acolytes of Mii Temple. A member of the influential Fujiwara family, he became spiritual adviser to Emperor Shirakawa (reigned 1072-86). For many years Shirakawa had no male heir by his Fujiwara empress and made several pilgrimages to Mii Temple in Kumano to pray for a son. An heir, Prince Atsuhisa, was at last born as a result of Raigo's prayers. Shirakawa was overjoyed and offered Raigo anything he wanted. Raigo asked nothing for himself but requested a raised platform for his temple upon which prayers could be offered. This was a privilege granted only to the fortified monastery of Mount Hiei, a stronghold of the yamabushi, literally "mountain warriors." These warrior-monks were a constant menace to Kyoto, periodically sweeping down and terrorizing the capital. Shirakawa (who had once complained that the fall of the dice, the waters of the Kamo River, and the monks of Mount Hiei were the only forces he could not control) was too afraid to grant Raigo's request. Raigo was infuriated. He retired to his cell where he shut himself away and refused to eat. Shirakawa sent conciliatory messages, but Raigo was implacable and eventually starved himself to death. Prince Atsuhisa died soon afterwards. Raigo's vengeful spirit changed into a thousand rats which infested the temple, destroying the Emperor's sacred books and scrolls and doing untold damage. Here we see a transformed Raigo, still in his priestly robe, chewing on a folded book. His ears and nose are not quite ratlike and suggest his human past. Smaller rats assist him in his destructive work, and a pack of rats dashes by excitedly in the background. "